|
Re: Carburetor tuning with a wideband A/F guage.
[Re: mopfried]
#1564806
01/18/14 02:56 AM
01/18/14 02:56 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
I drove the car last week. There was no detonation at all. I'll admit that the weather was in the 50s but at 10.07 to one and a pretty big cam it should do fine. Reading the plugs has been mentioned before but I'm not sure what to do. My understanding is that they have to be removed immediately after a WOT run. I have burned my hands trying this before with the tight clearance this car has. I was hoping that the Air/Fuel guage would be a good way to avoid burn scars!  I have a wide assortment of jets and power valves. Currently I believe I have #86 primaries and #94 secondaries. The original jetting was 85/93. My plugs are new. The plug wires have about 100 miles on them. cap and rotor are fresh too. Misfire? I hope not since everything has been replaced.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564807
01/18/14 05:18 AM
01/18/14 05:18 AM
|
Joined: Aug 2003
Posts: 43,119
Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,119
Bend,OR USA
|
I ran my duster 518 motor at or above 14.3 to 15.2 AFR at part throttle up here at 3500 Ft above sea level on my Innovate LM1 with the LC1 conversiion to dual wide band  I did run a cooler plug than most, Autolites AR3911 and AR3910, I also ran both the Champion RC12YC and the RC9YC, the motor ran well with all of them  I had it at between 12.8 to 13.5 AFR at WOT with the six pak and the single 1050 CFM Dominator carbs. I tested, I had issues early on with inadequate fuel supply(10 micron fuel filter between the tank and the pump  )the motor would leave the line at 14.2 AFR and cross the finish line at Bakersfeild(in really bad weather conditions) at 15.8  I got lucky and didn't hurt it, don't try that yourself Tune it until you like it, lean it down until it feels bad, richen it up until it feels bad again, find the sweet spot you like Then look closley at the plugs for the part throttle driving and put in several new plugs when you go test the WOT runs  IHTHs
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564808
01/18/14 11:37 AM
01/18/14 11:37 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
Tune the carb starting at the idle and then work your way up to WOT. If you jump around on your tuning sequence, it will take you allot longer to make progress.
At idle: if the engine makes best vacuum = best a/f for your engine. This may differ than one of ours.
Off Idle: Idle Air Bleeds/ Idle Feed Restricters will combine to give you the A/F that you are looking for. IAB's make tuning this rpm range a quicker process. Tune the off idle/low rpm cruising speeds to around 13 and see how it feels. Then lean it out to around 14 and see how it feels. Choose the a/f that is not lean enough to cause deination or heating up issues.
Accel to medium acceleration from cruising speed: main jets/power valve/power valve Restricters: tune these to keep your accel richer than your cruise but leaner than your WOT.
After the rest has been tuned, then use your rear jets/rear main air bleeds to tweak in your WOT a/f to around 12.5 for starters.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564809
01/18/14 02:32 PM
01/18/14 02:32 PM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
In order to adjust the different circuits of a carb, you have to understand the different circuits AND how they overlap and transition to each other. Do you have Emanuel's Holley book? Some sort of reference and instruction material is essential to get started. For instance, does your car cruise on the idle circuit or the main circuit? You need to know how to determine that so that you know which circuit to adjust. I will say this; set the idle mix where the engine likes it best, not by a target ratio. I have one engine that likes 13.6 for idle and one that likes 14.1. If you have 100% gasoline, the cruise will like about 14.7 which is stoich. But if you have 10% ethanol, that target will change. My engine's preferred WOT ratio will usually be somewhere between 12.5 and 13.2 depending. You'll also need jets, bleeds, power valves, small drill bits, maybe some wires and a lot of time to experiment. Trial and error is the path to success for you. We can give you some starting points or tell you what worked for us, but only you can find what is best for your particular combo.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: DaveRS23]
#1564810
01/18/14 04:13 PM
01/18/14 04:13 PM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Thanks for the suggestions so far!  I forgot to mention that here in CA the gas pumps have a sticker that reads "Up to 10% Ethanol" yet testing has found an average of 6% is common across the state. It makes sense that each car may respond differently. The compression, intake port design, exhaust system, camshaft, carburetor and ignition of each car combine to be unique to any car screwed together 40 years after Ma Mopar had her hands on it! I have a Holley book to peruse. I'll take a gander once I get out to the shop. Thanks again.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564811
01/18/14 04:31 PM
01/18/14 04:31 PM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
One of the toughest parts is figuring out which circuit you are on while cruising (let's say 30_70mph or so). As mentioned, once you know which circuit you are on, then you take allot of the guess work out of the tuning.
When you are out cruising, take notes of the a/f reading at different steady cruising speeds (ref: 30/40/50/60/70mph) then when you make a tuning change, write down the new a/f reading at these same speeds. This will show you exactly where your change made a difference good or bad.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Supercuda]
#1564815
01/18/14 10:42 PM
01/18/14 10:42 PM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
14.7 is the one number the OP can target and be fine, not necessarily perfect, but fine. We can get into a lot more intricacies of this, but it would simply be over the OPs head. I readily admit that the 14.7 target is not likely optimum, but the OP doesn't really have the abilities to set the cruise any finer. The idle and WOT, he can. Rather than limiting yourself to criticism, why don't you suggest the best process for a carb noob to set his cruise ratio. He has no tools, parts, or recording ability. At this point, anything more than I suggested will bury him. I was only trying to help a noob get to an acceptable point, not give him an engineering lecture.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Cab_Burge]
#1564819
01/19/14 03:30 AM
01/19/14 03:30 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Reading the plugs is often mentioned. I have never done this. I hate to sound like a newbie but in a 440 B body with 2" headers and power steering, how is this done without burning a persons hands? Every time I have changed the plugs I wait until the headers cool down. I'm a Carpenter by trade and obviously need my hands for work. Isn't the procedure to run the car hard at WOT then shut down and pull the plugs immediately? 
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564820
01/19/14 04:07 AM
01/19/14 04:07 AM
|
Joined: Nov 2003
Posts: 1,881
Pittsburgh,PA
RTSrunner
top fuel
|
top fuel
Joined: Nov 2003
Posts: 1,881
Pittsburgh,PA
|
Quote:
Reading the plugs is often mentioned.
I have never done this. I hate to sound like a newbie but in a 440 B body with 2" headers and power steering, how is this done without burning a persons hands? Every time I have changed the plugs I wait until the headers cool down. I'm a Carpenter by trade and obviously need my hands for work.
Isn't the procedure to run the car hard at WOT then shut down and pull the plugs immediately?
After your WOT run you can let the engine/headers cool before removing the plugs. The plug coloring will not change while the engine is off.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564823
01/19/14 01:52 PM
01/19/14 01:52 PM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
If you have access to a drag strip, I think that jetting to the best MPH is easier for most of us to set the WOT mix.
Just make enough back to back runs to establish a solid MPH base for comparison. Then jet up until the MPH starts to drop off, then step back to the optimum.
If at that point you want to start consulting the plugs, then okay.
It is much quicker to change main jets than to pull a spark plug on a hot BBM. And you do not have to learn the intricacies of reading the spark plugs, unless you want to.
I am not saying that this will result in a perfect A/F ratio. But it will get a good reliable result with a reasonable amount of effort and knowledge.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564824
01/19/14 04:17 PM
01/19/14 04:17 PM
|
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
|
top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
|
Greg, Here's what I've leaned - Quote:
I recently had the heads ported and changed to thicker head gaskets to lower the compression. Previously it was near 11.0 to one with 190+ cranking compression and detonated on the pump premium 91 octane gas we have here in CA.
It would help if you knew the current compression. With CR we can make a pretty good guess if the engine will be octane limited and less timing will be a neccessary work around. Do know the cc after the heads were cut?
Quote:
I have an AEM wideband EUGO air/fuel guage in the car with an O2 sensor in the RH header collector. Currently with the Grant 850 Demon carburetor I am able to get it to idle in the mid 14 ratio in neutral and in gear. Part throttle and full throttle are under 13.0 and even richer.
Assuming high overlap cam (compared to stock), a little richer at idle will be better. Better becaue it will make more power and therefore little to no drop in rpm when shifted from N to D on an automatic. Target idle AFR 12.7-13.5 Take a little initial timing out to match the richer mixture. This is a good reference for estimating initial timing based on cid, and cam duration.
http://www.demoncarbs.com/Tech/DemonSelectionGuide.asp
Quote:
I've stumbled along in life tuning cars by how they feel rather than using any type of guage. Most of my experience has been with stock or mildly modified engines. This car raises the stakes and I want to get it right.
Feel still has a place. Use it in conjunction with your WBO2 AFR for low speed, light throttle and cruising. If it feels weak or delay at low speed, you now will know what the AFR is, and see which tweak makes a change that helps. Same at highway. If you're driving at 60 mph and get lean surge, drop it to 55 and you'll see roughly how lean was too lean. Then install bigger main jets and see exactly if that helps 60 mph but also what impact it had on 55 mph.
Quote:
Is it fair to say that since I am able to get the A/F into range at idle, I should be able to get the part throttle and WOT into range with jets and power valves?
Yes. Although some BG and more recent Holley carbs need modifications to do this well. Try what have, as it is, first.
Quote:
Even though it reads that it is too rich, I smell no fuel and see no black smoke. I recall reading that for WOT the goal is in the 13.0 range but what is a good goal for part throttle?
WOT is a maximum load situation, especially in upper gears. Anywhere from 12.5-13.2 AFR depending on engine and fuel. With a little Eth mixed in, slightly richer will not surprise anyone. If more combustion cooling is needed, a little richer may be needed. Target range 12 - 13 in your case.
Part throttle depends on load and with a racy cam, rpm. At low rpm, richer mix is needed because of the exhaust diluting the air-fuel mix. Same issue as at idle as mentioned above. As rpm picks up, this problem goea away. Also load increases, lean mixtures can be used. How lean depends on your motor and loads. Drive it at 60 - 70 mph and see what it likes and how lean it will go at light throttle. At light throttle, when it gets too lean it will just try to die and then recover (surging). Don't wail on it! If there is too much timing, and you put load on it, bad things can happen and being lean isn't going to make it better.
At some point, as load increases, the mixture needs to get richer, much richer. This is when the power valve needs to kick in. When possible I like to dial in the WOT before the cruise. Safer in my opinion. Take it to the drag strip or a dyno and get best mph or hp under the curve. You can adjust this with the jets. Later, if there is a difference between the jets for best power and the jets for best cruising at 60 mph, you can look at the fuel curve and/or the power valve restrictions.
Quote:
Last week when I drove the car I felt a bit of an off idle stumble and lower idle vacuum. I thought I read here that it is suggested to set the timing to the highest manifold vacuum. Am I remembering that right? Currently it is set to 19 degrees initial and 33 total without vacuum
Uh. Alot of us thought that, but its not quite right. In neutral, there's no load, so you can keep adding timing and the engine loves it. You can then lean it to match and the engine loves that too. Then you put it gear and it goes. Ugh, the load is killing me.
Try setting the timing around 16 or 17, whatever the chart recommends. Then, using your vacuum gage, adjust the fine idle fuel mix for best vacuum. On an automatic, in theory set fuel mix for best vacuum in gear. In real word, it's often easier to set in neutral, then richen it about 1/8 turn and check it in gear.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Mattax]
#1564825
01/19/14 04:28 PM
01/19/14 04:28 PM
|
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
|
top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
|
Illustrations and explanations:
IMO the best book to start with is Urich & Fisher's Holley Carburators and Manifolds published by HP books. No BS. Urich was VP of Engineering at Holley, and the diagrams and explanations are top notch for a basic understanding of how any fixed venturi carb works. Many finer points are touched on or illustrated as well even though not discussed in detail. I come back to this book and notice things I didn't pick up on before.
You can find a g**gle book version, or go buy the real thing, used or new. Older editions just as good.
There's a great explanation and diagram in a sidebar on throttle relation to transfer slot. If you continue to have issues with off-idle, this is the section to look at. The throttle blade relationship to the slot is very important for idle and off idle AFR. Your Demon may have 'idle-eze' which means that if you can't get the proper throttle-slot relationship, it is not neccessary to drill the throttle plate. Instead you slightly open the idle-eze.
Last edited by Mattax; 01/19/14 04:39 PM.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564828
01/20/14 02:52 AM
01/20/14 02:52 AM
|
Joined: Aug 2003
Posts: 43,119
Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,119
Bend,OR USA
|
Try inserting a skinny wire in the idle air bleeds in gear to see if that helps on the idle AFR  If it does that means it wants smaller idle air bleeds which enrichen the mixture from idle to WOT On the fat when cruising you might be able to lean down the transition fuel feed channel, take the carb. apart and look at the slot in the middle of the throttle body that the throttle plates straddle, I drill and tap them for a allen head #6 brass set screw and then drill the set screw to make the channel smaller, make sure and figure out what size the stock hole is before drilling and tapping I bought two numbered drill bit sets, 1-60 and 61 to 70 with a pin vise to work on carb. circuit slike those You can make the babys (carbs.) purr like a satified kitty  As already said work on one circuit at a time, remember the idle circuit, the transition circuits, the primary and secandary as well as the power enrichment circuots all work at WOT  The idle and high speed bleeds should be used for the final fine tuning BTW, check your ignition timing from idle in nuetral to idleing in gear to see if that rascal is dropping the lead out of the mechanical advance at the lower RPMs Keep at it, you know your having fun and learning, correct  
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564830
01/20/14 10:12 AM
01/20/14 10:12 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
NICE TUNING REPORT!
* Idle in Neutral 1100-1200 rpms 13.1 to 13.5
- You need to be careful with this high of an idle. You may or may not be on the idle circuit and may lead to your metering screws no longer giving you the adjustment that you need. Your Neutral idle readings should be second in importance since you have an auto tranny. After tuning your carb in D (see below), the Neutral A/F readings may just be what they turn out to be.
* Idle in Gear 750-800 rpms 17.8 to 18.0 +
- I always suggest to tune an auto car in D with the emergency brake applied or someone holding the brake. I would suggest that the next time you have the engine warmed up after a short drive, put the car in D and apply the E brake. Then readjust your idle mixture screws for the best vacuum in D at the rpm of your choosing. You may need to keep readjusting your rpms as you go around the carb readjusting your metering screws.
-How many turns out are each of your metering screws?
I would work on the above first before moving forward to the cruising changes. These changes may affect the next tuning process.
---------------------------------------------------------------------------------------
* Slow acceleration from 2000-3500 rpms 10,9 to 11.6
- This could be a rich "transition" into the mains or it could be rich "main" jetting. If you could tell us what size Idle Feed Restricters you have, we might be able to give you a guess. Or, If you wish to lower your main jetting 2-4 sizes and retest your 2000-3500rpm A/F readings again, this might tell us too. If the large change in main jetting does little/nothing in the A/F readings in this rpm range, then this might point to the IFR's being to large which would be causing the rich readings. If the leaner main jetting changes the A/F readings by a point or more, then you know that your main jetting is where you are getting your fuel in the 2000-3500rpm range. A little testing in this cruising area will give you allot of info for your tuning in the near future!!!
* Slow acceleration from 3000-5000 rpms 11.9 to 12.4
- See above. Start with the lower rpm tuning first because the 3000rpm+ numbers may change due to the above idle/transition tuning changes.
* Steady cruise @ 40 mph in OD 12.9 to 13.3
* Steady cruise @ 50 mph in OD 12.0 to 12.5
* Steady cruise @ 60 mph in OD 11.9 to 12.3
- See above
---------------------------------------------------------------
* Faster acceleration from 2000-3500 rpms 11.5 to 12.0
* Faster acceleration from 3000-5000 rpms 12.6 to 13.1
- See above
--------------------------------------------------------------
Test WOT last.
Note: As already mentioned by another member, the idle/transition/main circuits TRANSITION into each other. There is no switch that turns one on and the other one off. When you change the idle circuit (IFR's, Metering Screws/Idle Air Bleeds), these changes will also affect the "transitioning" (you might be cruising on the transition circuit at lower rpms: "IFR's & Idle Air Bleeds will help tune this area) affect into the main circuit. This is why you start at the idle circuit with your changes and then move your tuning efforts up the rpm range. (All of these changes at the lower rpms will affect your higher cruising rpms and your WOT results). This is why you test WOT after all of the other circuits are tuned ON A STREET CAR.
Your notes that you have taken are invaluable in your efforts of tuning. Keep these notes to show yourself how far you have come in the weeks to come.
Note: Your main jets may or may not affect your cruising A/F numbers under 3000rpms or so. It just depends on the carb. Some carbs use the transition circuit for cruising and some use the main circuit for cruising.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564831
01/20/14 06:30 PM
01/20/14 06:30 PM
|
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
|
top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
|
Greg. Which circuit is doing what and why will make a lot more sense if you get that book. Used copy will be $10 including shipping through 'zon. It's also avaliable online through g**gle books, at least sample sections for free. Quote:
With this info, I see that I need to richen it up a bunch at idle in gear. It stumbled and stalled twice while leaving 2 different stop signs. I suppose that since this occurs at idle and not on the primary circuit, this is a matter of tweaking the idle mixture screws?
Yes and maybe. Yes it is a matter of adjusting the idle mix. Maybe it can be done with the mixture screws alone, but that is where you should start. See paragraph above where I wrote what the engine would do if too lean at idle. " Then you put it gear and it goes. Ugh, the load is killing me."
Quote:
I wouldn't think it would need more accelerator pump volume would it?
Get the idle and transition half decent before playing with pump shot.
Quote:
The "Slow acceleration" between 2000-3500 and 3000 to 5000 showed it to be really rich. This was done at light throttle , I assume entirely on the primary circuit? This makes me think I need to use smaller primary jets.
No. Definately not on the primaries in the lower rpms, maybe or maybe not the high rpms for reasons that Y0 already explained.
In my experience, primary circuit starts to dominates the fuel delivery somewhere around 60-65mph (about 3000 rpm) with factory tire size and street gearing. That is, about 25-6" tire diameter and 3.23:1 gearing. This will vary with booster type, venturi size, and air bleeds along with engine load and gearing all factor in.
Quote:
The faster acceleration testing showed leaner numbers than the slow acceleration. This was still done without hearing the secondaries open. I'm not sure what to make of that.
This is exactly how it should be. I was not clear in my explanation above. Once the vehicle is moving, as the throttle opens with increased load, the AFR should get leaner. Quote:
Maybe I need a power valve that opens sooner there? I have a 3.5 in the carb now.
Not just based on some AFR number, and certainly not based on what you observed. See previous comment. Power valve needs to open when the load gets very high. This can be anywhere from 60-90% full load. Once you get the rest figured out, you can experiment opening the power valve under less loads. It shoud not kick in hard, nor should it make the 3/4 thottle acceleration lazy. Not easy to nail down without lots of trials or very sophisticated equipment which few of us have.
Quote:
At WOT it shows that the higher RPMs it goes fatter. I guess that is safer than leaning out.
Yes and could be one or more reasons for this. Also 2nd gear isnt always the same as 3rd gear. Another reason to reserve that for later.
Quote:
My gut tells me to adjust the idle mixture screws to obtain a richer in gear reading.
Yes.
Quote:
It tells me to lean out the jetting front and rear.
No. One change at time. Even making just one change at a time within the idle circuit is very hard to do. Urich and Fisher will show you why far better than I, and they have diagrams.
My guess is that besides the mixture screws, you will have to try a little more and little less timing, and you will also end up adjusting the throttle position with the idle speed screw. IF that's what you end up doing, here's a time saver.
Take the carb off and measure the transistion slot visible under the throttles. Use a feeler gage or some wire of known diameter. About 0.020" - .035" should show. Write down how much slot shows for every quarter turn of the idle speed screw starting from the screw just touching to .040" Put the carb back on with the idle speed screw opening the throttle so just around .020-.025" of the slot shows.
As you tune the idle, once the engine is warm, you should be able to get it to idle nice without opening up the throttles more the .035" or shutting them more than .020" You see even at idle, the transition slot is contributing both fuel and air. Every time the throttle's idle position is moved, that contribution is effected.
So, first set the throttle so so it runs, but no more than .040". Then adjust timing and mix screws so it doesn't die when put in D. Then adjust for best vacuum in D. You'll have to experiment with a degree or two each way on the timing. As it runs better the rpm will go up, and you may have to adjust again. It's that type pf process. If you can't get the results needed without opening the throttle around over .035", then its time to let some air in through a hole. Your carb may have the 'idle-eze'. Instructions for that feature should be available from Grant, if that feature is on the carb. Urich and Fishe explain this under 'wild cams' and why getting this right is important for the off-idle performance.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Cab_Burge]
#1564832
01/20/14 10:46 PM
01/20/14 10:46 PM
|
Joined: Feb 2005
Posts: 4,311
Prospect, PA
BSB67
master
|
master
Joined: Feb 2005
Posts: 4,311
Prospect, PA
|
Quote:
.....BTW, check your ignition timing from idle in nuetral to idleing in gear to see if that rascal is dropping the lead out of the mechanical advance at the lower RPMs
This is the first thing you need to do. And make sure that you don't have a vacuum leak.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564834
01/24/14 01:25 AM
01/24/14 01:25 AM
|
Joined: Aug 2003
Posts: 43,119
Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,119
Bend,OR USA
|
Last edited by Cab_Burge; 01/24/14 04:14 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564835
01/24/14 09:33 AM
01/24/14 09:33 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
Nice job! Try to keep all four metering screws outward about the same amount during your tuning. Then once you have it dialed in and you just need to compensate for outside temp change, you could then just turn the front metering screws for minor adjustments. You will have to keep tweaking the A/F when the temps change through out the year, but it will now be a quick adjustment. You not only richened your in D idle A/F, you have also richened your off idle and low speed A/F too.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564837
01/24/14 11:41 PM
01/24/14 11:41 PM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
You needed to richen your idle since it was in the 17 range. You fixed that problem and now it is time to work your way up the rpm range.
After you make the next test run and if you see a rich condition off idle and lower cruise rpms, you will next need to check the IFR sizes and let us know.
Nice job!
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Cab_Burge]
#1564841
01/28/14 09:32 AM
01/28/14 09:32 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
Nice Job! Creep up on it one jet at a time since this change is affecting most of your cruising readings. Idle in D: Low 14's (If you have your strongest vacuum reading, then this is good) Light Accel: 11.6-13.6 (Rich 2000-3000rpms= Leaner main jet) 40-60mph Cruise: 13.1-14.0 (Try leaning it out a little more to find your lean limit = Leaner main jet) Leaning out the main jet will lean out your light accel and every reading the rest of the way up the rpm range. Your carb appears to be setup to cruise using the main circuit. Some do and some cruise on the transition into the main circuit. Now that you know, it will make your cruising tuning easier. Once you know what your strongest vacuum reading is in D, then as the outside temps changes, then tweak the front two metering screws to keep you in that range through out the year.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: YO7_A66]
#1564842
01/28/14 11:46 PM
01/28/14 11:46 PM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Thanks for the feedback. I appreciate any and all help that comes my way. I'm curious as to what effect adding Vacuum Advance might have on the A/F readings. I meant to work on the car after work but didn't get the time.
Last edited by Frankenduster; 01/29/14 02:15 AM.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564843
02/01/14 02:12 AM
02/01/14 02:12 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Yesterday I pulled the MP Chrome ECU and installed the Rev-N-Nator that I bought about a year and a half ago. Back then when I tried it, the engine detonated worse than it did with the Mopar ECU. I had to retard the timing to 29 degrees to get it to stop knocking. That put my initial at 15 and it felt lazy off idle. Since then I have learned how to set the advance curve in this distributor. I was going to try vacuum advance but the instructions read that their ECU isn't compatible with it. No problem. Theres more tuning to do to get the A/F readings closer to the ideal. I expected that the thicker head gaskets and lowered compression to cost me some power. I figured the head porting would offset it. As it is now, the car flat out scrams! It sounds great, it feels great. After all that I have been through in the last 8 months, I would have been satisfied with the same power but with NO detonation. Its a nice plus to have these changes result in MORE power too.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: YO7_A66]
#1564844
02/17/14 04:58 AM
02/17/14 04:58 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Last week after adding the H pipe to the exhaust, the readings changed again. I have read many times that when headers are installed, the engine often needs bigger jets. I figured that the H pipe would have had a similar effect. Somehow my 40,50,60 mph cruise readings are now really rich again in the 11.0 to 12.0 range. Its almost as if the 02 sensor is lying to me. Quote:
Idle in D: Low 14's (If you have your strongest vacuum reading, then this is good)
Light Accel: 11.6-13.6 (Rich 2000-3000rpms= Leaner main jet)
40-60mph Cruise: 13.1-14.0 (Try leaning it out a little more to find your lean limit = Leaner main jet)
Leaning out the main jet will lean out your light accel and every reading the rest of the way up the rpm range. Your carb appears to be setup to cruise using the main circuit. Some do and some cruise on the transition into the main circuit. Now that you know, it will make your cruising tuning easier.
I'm going to map the readings as-is again, then I'll reduce the jet sizes again. Oddly, at WOT it has gone into the 14.0 range. Its like the H pipe reversed the fuel curve to where it runs rich at cruise and leans out at WOT.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564845
02/17/14 06:24 AM
02/17/14 06:24 AM
|
Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
master
|
master
Joined: Jun 2006
Posts: 5,161
CT
|
Quote:
Last week after adding the H pipe to the exhaust, the readings changed again. I have read many times that when headers are installed, the engine often needs bigger jets. I figured that the H pipe would have had a similar effect. Somehow my 40,50,60 mph cruise readings are now really rich again in the 11.0 to 12.0 range. Its almost as if the 02 sensor is lying to me.
Quote:
Idle in D: Low 14's (If you have your strongest vacuum reading, then this is good)
Light Accel: 11.6-13.6 (Rich 2000-3000rpms= Leaner main jet)
40-60mph Cruise: 13.1-14.0 (Try leaning it out a little more to find your lean limit = Leaner main jet)
Leaning out the main jet will lean out your light accel and every reading the rest of the way up the rpm range. Your carb appears to be setup to cruise using the main circuit. Some do and some cruise on the transition into the main circuit. Now that you know, it will make your cruising tuning easier.
I'm going to map the readings as-is again, then I'll reduce the jet sizes again. Oddly, at WOT it has gone into the 14.0 range. Its like the H pipe reversed the fuel curve to where it runs rich at cruise and leans out at WOT.
At WOT I would expect it to lean out some after adding the H. I'm not sure why you'd get so rich under normal driving conditions though, but listen to what the AF gauge is telling you.
What carb are you running out of curiosity?
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564847
02/17/14 06:01 PM
02/17/14 06:01 PM
|
Joined: Jan 2003
Posts: 1,883
Northern OH
rapom
top fuel
|
top fuel
Joined: Jan 2003
Posts: 1,883
Northern OH
|
Since you have a BG carb you might be able to tune your cruise A/F where you like it with your regular jets. Then tune WOT with your Power Valve jets. A good carb will have replaceable power valve jets which can be changed. You have to remove the Power valve to get to them. Not sure where to buy them cheaply. Or they can be drilled out a little at a time.
Last edited by rapom; 02/17/14 06:04 PM.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: YO7_A66]
#1564850
04/08/14 07:03 PM
04/08/14 07:03 PM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
I just returned from a 950 mile round trip to Los Angeles and back. The Air/Fuel numbers still have me a bit confused. I thought that when a restriction in the exhaust system is removed, the carburetor sometimes needs to be jetted richer. In my case, after installing the 3" pipes and X section, the car runs richer. I was running in the 11.6 to 12.5 range at 70 mph cruise, 2800-3000 rpms. I have already reduced the jets from #86s to #83s before the exhaust work and the numbers were getting closer. After the exhaust work, the numbers went PIG rich! Member YO7 A66 wrote this: Quote:
Or, If you wish to lower your main jetting 2-4 sizes and retest your 2000-3500rpm A/F readings again, this might tell us too. If the large change in main jetting does little/nothing in the A/F readings in this rpm range, then this might point to the IFR's being to large which would be causing the rich readings. If the leaner main jetting changes the A/F readings by a point or more, then you know that your main jetting is where you are getting your fuel in the 2000-3500rpm range.
Note: Your main jets may or may not affect your cruising A/F numbers under 3000rpms or so. It just depends on the carb. Some carbs use the transition circuit for cruising and some use the main circuit for cruising.
I'm not familiar with the Idle Feed Restrictors unless they are the thin diaginal slots in the throttle bores. Cab Burge suggested blocking part of the IFRs with wire to see if they are too big for my needs. I need to learn what the IFRs actually are before doing this.
I'm going to lean out the primaries again to see if the numbers move. I'm just surprised that a less restrictive exhaust made the car run richer. I didn't change anything else.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: davenc]
#1564854
04/09/14 03:36 AM
04/09/14 03:36 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
The carb is the "Street" Demon. I've had it since it was new.
Ever since I put this wideband guage in, the numbers have been erratic. My inexperience in these matters led me to believe that the rowdy cam was responsible for that. I have had the carb apart and found it to be clean inside. The gaskets are fresh. I've sprayed carb cleaner at every point of the carb with the engine running and cannot find a vacuum leak anywhere. The metering block has no removeable PVCRs. I am not sure about the Idle feed restrictors. I'm not even sure what they are. I'll have to do a google search on that.
***********************************************************************
I just did a search. If what I saw was correct, the IFRs are a passage in the metering blocks. I gather that some are drilled during the machining process and left that way. Others are threaded so different size jets can be used for additional tuning. I am pretty sure that mine are only drilled.
Last edited by Frankenduster; 04/09/14 04:04 AM.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564855
04/09/14 10:43 AM
04/09/14 10:43 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
Your readings should be fairly smooth on the gauge especially at any cruising speed and up to WOT.
Since your reading has always done this, you might want to check for exhaust leaks around or upstream from where your sensor is mounted.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564856
04/09/14 11:01 AM
04/09/14 11:01 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
If you dropped 2 jet sizes and found no A/F improvement, then you may want to to go back to previous jetting and look elsewhere. Dont worry about WOT until you get the Idle, the transition and the cruise A/F correct.
If your metering blocks do not have screw in idle feed restrictors, then i would suggest tapping them or buying replacement blocks that have this feature. If you really want to nail down your transition A/F readings, then you will need to be able to tune this part of the circuit.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564857
04/09/14 11:17 AM
04/09/14 11:17 AM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
If you feel that you have located the IFRs, then as a test you can mike a few small wires like from a stranded 16 guage. And use a small wire in the IFRs to limit the flow. The IFRs are small, so the wire should be small. I would try to stay under .010, if you can find one that small.
Also, make sure that the wide band is calibrated correctly. You dropped the mains and the engine didn't like it, but the wide band did reflect the change, didn't it?
If you want to define when the mains come in, here is a simple way to do that; just tape over the openings under the metering block that feed the boosters. When you come off the slot to the mains the engine will just stop due to lack of fuel. A short test drive and you will know exactly where your main circuit is and when you are or aren't on it.
You do need to know if you are cruising on the mains or on the idle/transition circuit. The taped off boosters will tell you that.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: YO7_A66]
#1564858
04/09/14 11:41 AM
04/09/14 11:41 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
Once you get the gauge to settle down at cruise, you may want to consider "logging" your tuning changes.
When i make tuning changes, i like to write down info so i can review what the A/F did per that change. I like to write down the A/F readings at 30/40/50/60 mph (steady cruise). If you do this, you can reflect on what your tuning change made at different speeds. This will help you to understand where your changes are taking affect.
If you do this, then if you make a 2-4 jet change, then your readings would show you when your mains are affecting your A/F readings.
You will be able to make quicker tuning changes as soon as you find out "when" your mains start influencing your A/F readings. The mains will not come on like a switch, they will gradually start introducing fuel to the engine depending on throttle position. Once you know when the mains start in, and you have a tuning problem before this rpm, then you know to start working on the transition or the idle circuit.
But as mentioned, you need to figure out why the gauge is jumping around. Exhaust leak, clean 12v supply to the A/F module?
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564859
04/09/14 11:51 AM
04/09/14 11:51 AM
|
Joined: Jan 2003
Posts: 4,395
The Pale Blue Dot
Skeptic
master
|
master
Joined: Jan 2003
Posts: 4,395
The Pale Blue Dot
|
Quote:
I thought that when a restriction in the exhaust system is removed, the carburetor sometimes needs to be jetted richer.
I'm going to lean out the primaries again to see if the numbers move. I'm just surprised that a less restrictive exhaust made the car run richer. I didn't change anything else.......
The jet change resulted in less power and one incident of of detonation despite the gauge reading richer than the target.
Just some thoughts/questions. Did you check backpressure and verify a reduction? A 70 mph cruise should not have a significant change there, unless you had a really bad exhaust before- I've worked on plenty of cars that had bad Cats that would drive fine until you stood on it, then would fall on their face.
and far as the the jet change don't focus on a "target number", give the engine what it wants. You don't have efi, so there are going to be cylinders that run leaner than others, and you are not monitoring each cylinder. I'd suggest you swap back the #83s and check again. If engine is happy, leave them. If not there may be a fuel problem- delivery, poor quality, sucking air, or carb. If the reading are inconsistent there could be a problem with the gauge. HTH, Steve
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564861
04/09/14 06:14 PM
04/09/14 06:14 PM
|
Joined: Jan 2003
Posts: 3,575
The Netherlands
BigBlockMopar
master
|
master
Joined: Jan 2003
Posts: 3,575
The Netherlands
|
Are you really sure the exhaust is airtight in front and around the O2-sensor? Have you tried installing the sensor in the other tube for comparison? I've installed 2 AFR-gauges in my '60-NewYorker with the rollercammed longram intake engine in it. But the more I try to tune that system, the more I just want to go EFI with that setup.  I've got some clips of the gauges in the '60 on my Youtube channel to view.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: davenc]
#1564864
04/10/14 01:52 AM
04/10/14 01:52 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Shoot, now I'm going to have to look that up. I bought it almost 10 years ago. Today while I was changing jets, I saw that what I think is called the Idle Feed Restrictors are UNtapped. **************************************************************** It appears that I have a Speed Demon. The Demon site also confirmed that the original jetting is 85/93. I currently am at 83/92. http://www.demoncarbs.com/Tech/SpecCharts.aspThe carb CFM calculator on the Summit Racing site shows that I need a 788 cfm carb for street use and a 963 cfm for racing. This is for a 493 engine with a 6300 rpm max rpm. These are surely guidelines but not absolutes. The ThermoQuad carbs found on the 70s 440s were 850s and I doubt that anyone spun them to 6300 rpms!
Last edited by Frankenduster; 04/10/14 02:11 AM.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564865
04/10/14 11:45 AM
04/10/14 11:45 AM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
The new Street Demon is similar in architecture to the ThermoQuad and has only been out a couple of years. If you have had your carb for 10 years or so, it won't be one of the new style Street Demons.
IFRs are usually just a drilled orifice, just like the PVCRs. So you either drill and tap them and buy a handful of bleeds. Or you can get some thin wires and if necessary, some small drill bits. Same results either way.
I have a street/strip 499 that pulls to about 6,000. I went from an 850 to a 950 and then to the 1050 Dominator that is on there now. But the Dominator is a chore to tune for the street. If the carb is tuned properly, you will be hard pressed to over-carb a hot 500" Mopar.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: DaveRS23]
#1564866
04/11/14 05:49 AM
04/11/14 05:49 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Quote:
I have a street/strip 499 that pulls to about 6,000. I went from an 850 to a 950 and then to the 1050 Dominator that is on there now. But the Dominator is a chore to tune for the street. If the carb is tuned properly, you will be hard pressed to over-carb a hot 500" Mopar.
I read elsewhere that it is suggested to run leaner jetting then enlarge the PVCR to get the richer A/F only when needed. (On demand)
Sounds great, but how do I go about it? Do I drill the passages out in small increments and test drive the car?
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564867
04/11/14 11:42 AM
04/11/14 11:42 AM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
Quote:
Quote:
I have a street/strip 499 that pulls to about 6,000. I went from an 850 to a 950 and then to the 1050 Dominator that is on there now. But the Dominator is a chore to tune for the street. If the carb is tuned properly, you will be hard pressed to over-carb a hot 500" Mopar.
I read elsewhere that it is suggested to run leaner jetting then enlarge the PVCR to get the richer A/F only when needed. (On demand)
Sounds great, but how do I go about it? Do I drill the passages out in small increments and test drive the car?
When your car cruises on the main circuit, I have found that most carbs are too rich there. But most of the carbs I have had have been very close on the WOT mix. So, in order to keep the WOT mix right, when you pull fuel from the mains you need to add it back with the PVCRs.
When doing that, I have also found that the leaner mains will cause the engine to want the extra fuel from the PVCRs sooner, so a quicker opening power valve is necessary to eliminate a hesitation.
As I stated above, on drilled orifices like PVCRs and IFRs, I just use small wires to reduce the flow and small drill bits to enlarge. This is not better than drilling and tapping the orifices for bleeds. It is just quicker, easier and cheaper for me. And gets the same results.
Most of my engines have been comfortable with the cruise in the mid to upper 14s.
Now if your engine cruises on the idle/transition circuits, some hard compromises/choices may have to be made. That is the situation with the Dominator on my Cuda.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564870
06/30/14 12:43 AM
06/30/14 12:43 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
While lately I have been concerning myself with the possibility of a camshaft and converter change, I'm still curious about the way this car runs so rich at cruise rpm. Nothing has changed since the last few posts in this thread, but today I did order a Quick Fuel metering block kit with replaceable bleeds. It seems that since the car runs strong at WOT with the #83 jets but the guage reads rich at cruise with them, I'm going to try using smaller main jets and larger orifices in the PVCR. It was suggested to try using a lower rated PV to get a head start against a WOT lean-out condition (or stumble). I'll certainly try that too. I also ressurected this thread in direct response to a thread in the General forum about members that do NOT post results after asking for help.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564872
06/30/14 08:48 AM
06/30/14 08:48 AM
|
Joined: Jul 2013
Posts: 1,272
Northern Calyfornua
Sxrxrnr
pro stock
|
pro stock
Joined: Jul 2013
Posts: 1,272
Northern Calyfornua
|
Interesting reading. I have acquired a dual 'Fast' unit for use on my 512 six pack. Have not installed bungs yet, so yet to get seriously into this. Only have shoved sensors up the tail pipes to get a feel.
Was curious about large variations and rich readings on your engine, particularly at cruise.
Could some random misfire,,,example plug wire, leaky valve, dist cap, vacuum leak, carb issue cause this. Certainly a misfire would cause a overly rich reading as it leads to unburned fuel past the sensor.
Could a contaminated o2 sensor cause such possible incorrect or random readings.
I would pull my carpet, or perhaps buy another cable to see what readings are seen on the opposite exhaust side before continuing to beat myself up chasing possible jetting issues,,,so far they don't seem to be improving the answers to your basic concerns.
Doing this proactive troubleshooting by eliminating the possibility or controlling for any of these possible variables could prove helpful to gaining the piece of mind you seek.
On the other hand, I am learning from the input of others and would hate this thread come to an early end.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: rapom]
#1564874
10/09/14 02:37 AM
10/09/14 02:37 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
Quote:
Since you have a BG carb you might be able to tune your cruise A/F where you like it with your regular jets. Then tune WOT with your Power Valve jets. A good carb will have replaceable power valve jets which can be changed. You have to remove the Power valve to get to them. Not sure where to buy them cheaply. Or they can be drilled out a little at a time.
I replaced the primary metering block with a "Quick Fuel" unit. The QF has tiny screw it "jets" in the metering block behind the power valve. I used the same #83 jets that I was using for a while. The A/F numbers went a bit richer at cruise. Maybe the QF block flows more fuel?
I posted in the RACE forum but some responses caught me off guard. I was asked if I had annular or downleg boosters. Some mentioned IABs or IFRs. I wish I knew how to respond but once I get beyond jets and power valves, I'm not familiar with much else. I've looked for pictures of the annular and downleg boosters to see how they compare to mine but I can't find any that make sense to me. I don't have many gearheads nearby so I'm having a tough time here. Idle air bleeds? Idle Feed Restrictors? 
I bought this Demon in 2003. What I do know is that it is an 850 with Vacuum secondaries and it came with an electric choke. I don't have the actual model number written down but I thought it came with #85 primaries and #92 secondaries. Looking back, the tuning was heading the right way until I added the X pipe and Dynomax mufflers. Those changes sent the A/F numbers almost 2 points richer!
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564875
10/09/14 10:33 AM
10/09/14 10:33 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
""I replaced the primary metering block with a "Quick Fuel" unit. The QF has tiny screw it "jets" in the metering block behind the power valve.""
There is a good chance that this block moves more fuel.
These are your PVCR's (Power Valve Channel Restrictors). You can swap these out to add/reduce fuel once the power valve is open. The Main Jets, Power Valve (2 door and 4 door: each door adds more fuel), PVCR's, and the Main Air Bleeds (or High Speed Air Bleeds) all work together. You change one of these and it affects the others and the main circuit. (Note: dont worry about tuning the PVCR's at this time.)
Boosters:
Straight, Downleg, Annular, and the higher end units have replaceable boosters. There may be more but these are the common boosters. I attached a picture showing downleg (bend downward into the carb) on the right and it appears to be an annular (holes around the inside of the barrel) on the left.
The A/F numbers are now 2 points higher after exhaust change. You should always recheck the tuning after changes to the engine. You might have had exhaust leaks prior causing the sensors to be reading wrong. 2 points is a big change.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1564877
10/10/14 04:16 AM
10/10/14 04:16 AM
|
Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
|
master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
|
Try using a video camera to mounted to be able to clearly read the gauge and show how your driving it. It's nice to be able to see the tach and hear the motor in the video clip too. You can watch it at your leisure.
I email video clips to the guy who adjusts my EFI on my '68, he makes adjustments and emails me back a new tune to download and upload into my SCT tuner to download into my factory OBDII ECM.
It was just plane dangerous and scary trying to wind out my carbureted car through the gears while reading the wideband. Video really helps
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: jbc426]
#1564878
10/11/14 02:23 AM
10/11/14 02:23 AM
|
Joined: Jan 2003
Posts: 1,490
smyrna,tn
draginmopars
pro stock
|
pro stock
Joined: Jan 2003
Posts: 1,490
smyrna,tn
|
We just mounted a smaller tach and the A/F gauge (both temporary) until carb is dialed in (E-85) above the oil and water to monitor while going down the track now working on mounting a cam to record the vitals. 
Ha-Ha Racin
Havin Fun 101
Howard
68 "Cummins" Satellite
70 W-2 449 "More Door" Dart
70 340 Dart Swinger, 4spd
71 360 Dart Swinger
72 540/ 518 Dart Swinger
73 airwolf 446/a-500 Cuda
73 "Cummins" Crew cab-car hauler
84 446 Dodge Rampage (tube chassis)
92 CTD 11' flat bed
92 CTD club cab
07 Dodge Caliber
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Steve Bryant]
#1564881
10/11/14 11:48 AM
10/11/14 11:48 AM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
It's a shame that there is not an easy way to record A/F and RPM and then display in graph form. When you see the info spread out in a graph, it is much more useable. The details and trends become apparent.
The LM-1, though a bit clunky, was the best at this that I have seen. But apparently the newer versions have not worked as well.
For anyone looking to start tuning with a wide band, I would strongly suggest getting a combo with at least A/F and RPM recording ability.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: DaveRS23]
#1564882
10/11/14 12:46 PM
10/11/14 12:46 PM
|
Joined: Oct 2003
Posts: 11,684
W. Kentucky
justinp61
I Live Here
|
I Live Here
Joined: Oct 2003
Posts: 11,684
W. Kentucky
|
Quote:
It's a shame that there is not an easy way to record A/F and RPM and then display in graph form. When you see the info spread out in a graph, it is much more useable. The details and trends become apparent.
The LM-1, though a bit clunky, was the best at this that I have seen. But apparently the newer versions have not worked as well.
For anyone looking to start tuning with a wide band, I would strongly suggest getting a combo with at least A/F and RPM recording ability.
My LM-2 has worked great and LogWorks displays the recordings as a chart. If I knew how to take a screen shot with windows 7 or 8 I'd post a graph.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: justinp61]
#1564883
10/11/14 10:22 PM
10/11/14 10:22 PM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
Quote:
Quote:
It's a shame that there is not an easy way to record A/F and RPM and then display in graph form. When you see the info spread out in a graph, it is much more useable. The details and trends become apparent.
The LM-1, though a bit clunky, was the best at this that I have seen. But apparently the newer versions have not worked as well.
For anyone looking to start tuning with a wide band, I would strongly suggest getting a combo with at least A/F and RPM recording ability.
My LM-2 has worked great and LogWorks displays the recordings as a chart. If I knew how to take a screen shot with windows 7 or 8 I'd post a graph.
WHEN the LM-2 works, it has been great. But there have been a lot of issues with it. So many that Innovate took the Tuner page down.
Is the page back up yet? Have they for sure got the problems resolved with the LM-2? If so, then it should be the "go-to" unit for tuning.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: DaveRS23]
#1564885
10/12/14 12:29 PM
10/12/14 12:29 PM
|
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
|
New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
|
Quote:
It's a shame that there is not an easy way to record A/F and RPM and then display in graph form. When you see the info spread out in a graph, it is much more useable. The details and trends become apparent.
The LM-1, though a bit clunky, was the best at this that I have seen. But apparently the newer versions have not worked as well.
For anyone looking to start tuning with a wide band, I would strongly suggest getting a combo with at least A/F and RPM recording ability.
Attached is a my last run recorded on my LM-2. Maybe later when I have time I'll try to explain all that's going on but there is a lot! The converter seemed to let go on that run and I lifted, that's why the RPM drops in second gear. I can't imagine wideband tuning by reading a gauge real-time. I'm recording 7 things on my 4 input channels, in addition to the RPM channel.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: @#$%&*!]
#1564886
10/12/14 09:10 PM
10/12/14 09:10 PM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
Quote:
Quote:
It's a shame that there is not an easy way to record A/F and RPM and then display in graph form. When you see the info spread out in a graph, it is much more useable. The details and trends become apparent.
The LM-1, though a bit clunky, was the best at this that I have seen. But apparently the newer versions have not worked as well.
For anyone looking to start tuning with a wide band, I would strongly suggest getting a combo with at least A/F and RPM recording ability.
Attached is a my last run recorded on my LM-2. Maybe later when I have time I'll try to explain all that's going on but there is a lot! The converter seemed to let go on that run and I lifted, that's why the RPM drops in second gear. I can't imagine wideband tuning by reading a gauge real-time. I'm recording 7 things on my 4 input channels, in addition to the RPM channel.
Need a little more smoothing on a couple of those graphs, I think.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: DaveRS23]
#1564887
10/13/14 12:19 AM
10/13/14 12:19 AM
|
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
|
New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
|
Quote:
Need a little more smoothing on a couple of those graphs, I think.
AFR is spikey at idle because of leaky headers (soon to be scrapped) and has some spikes around where I lifted off the throttle. AFR is smooth enough where I care (WOT). Other than that it's all useful information. The other traces are ON/OFF, 0-5volt and what may appear to be spikes are control signals I'm monitoring. The obvious voltage spikes can't really be 'smoothed away' without modifying the signal and I'd really like to keep them anyway. The red trace doesn't go to zero because when it's not 'High' it shows the voltage on the coolant temperature sending unit. I can look at that trace and see what the engine temp was at any point. It works so well that I added the transmission temp to the tan signal but it needs to be amplified some to be useful.
After using this Innovate LM-2 I can't imagine trying to do any tuning with an in-dash gauge. Just the problem of the slow response time of the display prevents anything but steady-state readings. With the recording I can see how signals change over short time intervals and correlate them with other events such as transbrake release, shift points, and such.
I also find the OBD2 feature more useful than I thought. It will display DTC's and tell you what they mean (for the generic ones) or clear them for you.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: @#$%&*!]
#1564888
10/13/14 10:28 AM
10/13/14 10:28 AM
|
Joined: Jan 2003
Posts: 12,017
Benton, IL.
DaveRS23
Special needs idiot
|
Special needs idiot
Joined: Jan 2003
Posts: 12,017
Benton, IL.
|
"After using this Innovate LM-2 I can't imagine trying to do any tuning with an in-dash gauge. Just the problem of the slow response time of the display prevents anything but steady-state readings. With the recording I can see how signals change over short time intervals and correlate them with other events such as transbrake release, shift points, and such."  It may be useful to mention to those that are not familiar with the LM-1 and LM-2 that the black and the pink lines are all that most 1st time tuners are going to have and need. At first glance, that particular log could look a bit confusing. Thanks for the clarification.
Master, again and still
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: DaveRS23]
#1564889
10/13/14 11:29 PM
10/13/14 11:29 PM
|
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
|
New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
|
Quote:
It may be useful to mention to those that are not familiar with the LM-1 and LM-2 that the black and the pink lines are all that most 1st time tuners are going to have and need. At first glance, that particular log could look a bit confusing.
Thanks for the clarification.
You're right, I should have explained a bit more but was in a hurry to head to Woodburn (as a "Crew Chief" in a runner-up effort).
Pink is AFR, numbers on left in pink for the scale
Black is RPM
Red is transbrake button and coolant temp
Green is transbrake output from delay box
Blue is a throttle function and then an electric shift signal
Tan is another throttle function and a barely detectible and noisy trans temp signal.
The engine idled well in spite of the ugly AFR readings, otherwise I would have fixed it. Very little time was spent at full throttle as something let go barely into second gear, and full throttle.
For comparison, here's the prior (uneventful) run:
This is 1/8th mile, on a 1/4 mile run it hits 6900rpm @ 132+mph
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: @#$%&*!]
#1564890
11/03/14 12:32 AM
11/03/14 12:32 AM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
It has been awhile since I've been tinkering with the tune of the Charger. Mainly my delay stems from the fact that I have a cam swap planned that would render any current tune ineffective. I'm swapping out the Lunati 316/326 for the Mopar 284/528 to gain better low rpm street manners. The MP cam with less overlap should improve things.
Today a buddy came over with his 71 Challenger. He has the same brand of wideband guage as I, the AEM.
Paul wasn't happy with the performance of the car since he did a cam swap. He had been tinkering with the carburetor and timing to try to improve the A/F #s and the power but the car ran too lean at idle, too fat at WOT, power was down and it dieseled upon shutdown even with a 900 idle. He has a 5 speed from American Powertrain and the engine is a 340 based 416 with a Holley Street Avenger 770.
His timing was set to an initial of 10 and a total or 25. He said that he had it set there because any more timing made the dieseling worse. I learned HERE that ignition timing is often blamed for the "run-on" condition but isn't always the case.
I disconnected the throttle cable and backed off the idle speed screw, then ran the engine at 3000 rpms. After 25-30 seconds, I let the engine rev down, then shut it off. NO run on, no spitting, snorting, just silence. I told him that his dieseling was probably due to partially open throttle blades at idle. I bumped the timing to 18 initial, 33 total and backed out the idle mixture screws to get the guage in the 14-15 zone.(Idle in neutral) The car runs great, makes more power than before and does not run on. It still reads rich at cruise so I think it is in the same situation as I am with the Charger: It needs smaller primary jets with a bigger PVCR.
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: Kern Dog]
#1916220
09/20/15 06:19 PM
09/20/15 06:19 PM
|
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog
OP
Striving for excellence
|
OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
|
UPDATE I have put about 500 miles on the new cam without digging into the carb. It runs great but the A/F guage has been in the 10.9 to 12.0 range at cruise and low 13.0 range at idle. I changed the plugs and checked again. The old plugs smelled of gasoline so I expected to see some slight change. It did seem to clean it up a bit. I pulled out the 3.5 power valve and #83 jets and installed a 6.5 power valve and #82s. Throttle response did improve and I am now able to get the idle in Park and idle in gear numbers in the mid 14s. Cruise is still tricky but it is closer than before. At steady 50 mph in drive, I'm seeing a range of 12.0 to 13.8. The guage readings really move around a lot, maybe that is common for this AEM model? While idling, the guage momentarily reads lean as I hit the throttle, followed by going down to the high 11.0 range. I guess this is tunable with different accelerator pump cams, maybe one that rises faster but ultimately has less overall lift? There was zero detonation when driving today, sunny and mid 90s here. It seems like it is running better than ever. It sure feels fast. 
|
|
|
Re: Carburetor tuning with a wideband A/F guage.
[Re: jb500]
#1916570
09/21/15 09:30 AM
09/21/15 09:30 AM
|
Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,443
Indiana
|
""It runs great but the A/F guage has been in the 10.9 to 12.0 range at cruise and low 13.0 range at idle.""
""At steady 50 mph in drive, I'm seeing a range of 12.0 to 13.8""
Start with your in gear idle A/F. Low 13's are ok, but you might be able to lean it out to 13.8 or so as long as your vacuum numbers stay good. Use your metering screws to get this adjustment (and your internal adjustment are your Idle Feed Restrictors)
Once you have your idle in gear A/F where you want it, then test pulling away from a stop at a normal speed and watch the A/F readings. Dial in your pump cam/squirter to get this in the 13's or so. Just light throttle for now.
After you have the pump cam setup, then take notes of your "lower" cruising speeds again (30,40,50mph). You should be able to get these numbers in the upper 13's to low 14's by using your Idle Air Bleeds. (Your IFR's are also contributing). Each time you change your IAB's, you will need to readjust your Metering Screws.
After you have the IAB's sized correctly, then test your 50-75mph (or what ever "upper" speed you normally cruise). This range is tuned with your Main Jet (and the external adjustment is your Main Air Bleeds).
Once you have all of these set, then test your cruise to hard accel. Try testing at different speeds from 30mph to 75mph and watch for lean or rich spikes. This adjustment is your Power Valve and your Power Valve Channel Restricters. Timing is the PV, and the flow are the PVCR's. If you get a rich spike, then you could lower your PV rating. If you get a lean spike, then you could raise your PV rating. If you can't get either one tuned out with the PV, then test other sizes of your PVCR's.
Once this is all done, then it is time for your WOT testing. With a street car, I like to start at a cruise (maybe 45-55mph) and then go to WOT and write down your A/F spike and your A/F reading at your shift point. Then tune the shift point with your Secondary Jets for approximately 12.5 A/F. Once you have the WOT shift point, then you can tweak the rich/lean spike with your PV rating.
Start at the bottom of the driving range (idle) and tune your way up to WOT (last). If you jump around on tuning your circuits, then you are just going in circles.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
|
|
|
|
|
