Re: Cam break in is done!....Now more questions!
[Re: Twostick]
#1492864
09/02/13 02:02 AM
09/02/13 02:02 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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OP
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Posts: 18,493
Granite Bay CA
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Quote:
Make sure you have no leaks UPSTREAM of the sensor. Any header tubes that might be leaking or flange gasket leaks will suck in air and give you a lean reading.
I don't recall your cam specs but if it has a lot of overlap, exhaust reversion will cause random misfires (that choppy idle sound)and the O2 sensor will read lean even if it is actually rich. Misfire = no oxygen was used so it get pumped out past the sensor which does its job and reads it.
Get the engine to sound happy first and then use the readings to tell you what changes to make. They will not likely be where you expect when you are done at least as far as idle and cruise go.
Kevin
Good points, Kevin. There are no detectable exhaust leaks. Cam overlap? Oh yeah! Plenty of it. I didn't consider that.
I am curious as to what jets other guys are running in similar engines. When I switched from #86 to #88 primary jets, My IN GEAR idling readings fattened up from over 17 to around 15.8 to 16.0+ so I wonder if it will improve further with #89 or #90 jets. That seems pretty huge though.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492865
09/02/13 03:04 AM
09/02/13 03:04 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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As stated, this Barry Grant 850 came with #85 primary jets, #93 secondary jets and a 6.5 Power valve. I figured that these were virtual copies of the Holley line with a fancier finish. I was looking on the Summit site and saw that the Holley Street Avenger 870 comes with #78 primaries, #82 secondaries and a 4.5 PV: http://www.summitracing.com/parts/hly-0-81870?seid=srese1&gclid=COP_-4CDrLkCFYU5Qgod8VsAzAHuh? A carb with a higher CFM rating has smaller jets and power valve?
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492867
09/02/13 08:54 AM
09/02/13 08:54 AM
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Joined: Feb 2005
Posts: 4,314 Prospect, PA
BSB67
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master
Joined: Feb 2005
Posts: 4,314
Prospect, PA
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It sounds like you are not a jet change away or the turning of a idle screw away from this thing running right. You might consider the following: 1) Tell everyone again what you have. 2) Reminded everyone what you have changed in the last few months and why. 3) Describe the symptoms that you are trying to improve. When you are trouble shooting keep all of the symptoms in mind but methodically and systematically work on one at a time. They may, or may not have the same root cause. Everyone here is trying to help, but remember, we're not there and we're sort of throwing things out there to see what sticks. Furthermore, they are opinions, and some are diametrically opposed and not correct. You'll need to sift through that and put some question marks up in your mind. Finally, if IIRC, you have a huge cam. A difficult place to start for a guy that does not understand how a carb works. I would actually suggest that maybe take a break from 10 posts per day on multiple forums, and instead read and understand how a carb works.
Last edited by BSB67; 09/02/13 08:57 AM.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492868
09/02/13 09:30 AM
09/02/13 09:30 AM
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Joined: Jan 2003
Posts: 5,443 Indiana
YO7_A66
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master
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Posts: 5,443
Indiana
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""Sorry, I'm not sure what this means."" No problem. The picture shows the "air bleeds" (8 goldish in color with the flat screw driver slot. 4 in the front and 4 in the back). The reason that I am asking about the carb is because we know that you are working with a BG 850-VAC unit, but there are different levels. Some may have or some may not have the "screw in" air bleeds which are much easier to tune.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492869
09/02/13 10:54 AM
09/02/13 10:54 AM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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master
Joined: Mar 2008
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Ontario, Canada
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I would be trying a differenet carb. Did you try holding you hands over the front two barrels like a chock?? Did you spray looking for vacuum leaks? Way lean may have been you detonation problem all along I'd be trying a different carb
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Re: Cam break in is done!....Now more questions!
[Re: Dodgem]
#1492870
09/02/13 11:46 AM
09/02/13 11:46 AM
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Joined: Feb 2005
Posts: 4,314 Prospect, PA
BSB67
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Prospect, PA
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How do you know its not the intake?, hose leak, bad PCV valve.
Although, like you and Kevin have said....look for a leak., and make sure the mining isn't moving around between in-gear and neutral idle speeds, throttle plate position, then IFR, based on what I remember on how he got here without re-reading anything. But, I'm having a hard time keeping track.
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Re: Cam break in is done!....Now more questions!
[Re: BSB67]
#1492871
09/02/13 12:31 PM
09/02/13 12:31 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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Posts: 5,746
Ontario, Canada
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Quote:
How do you know its not the intake?, hose leak, bad PCV valve.
Although, like you and Kevin have said....look for a leak., and make sure the mining isn't moving around between in-gear and neutral idle speeds, throttle plate position, then IFR, based on what I remember on how he got here without re-reading anything. But, I'm having a hard time keeping track.
Well I don't he has to check everything! But GB carbs have a real hit and miss reputation???
Try another carb and if it's the same it's something else.
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Re: Cam break in is done!....Now more questions!
[Re: BSB67]
#1492872
09/02/13 03:20 PM
09/02/13 03:20 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
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Quote:
It sounds like you are not a jet change away or the turning of a idle screw away from this thing running right. You might consider the following:
1) Tell everyone again what you have. 2) Reminded everyone what you have changed in the last few months and why. 3) Describe the symptoms that you are trying to improve.
I want to thank everyone that has attempted to help. I know that it can be difficult to know what is going on past the keyboard and monitor. Its even worse when some details get left out.
The 440/493 made decent power and idled well with the previous combo. It is a 440 block .030 over with flat tops, a 4.15 stroke crank and Edelbrock aluminum heads, 84cc UNported. 2" TTI headers and a 2 1/2" exhaust system. Mopar Performance electronic ignition with a chrome ECU. Distributor has been modified to be limited to 14 degrees of advance. I used to set it at 16-17 degrees with it advancing to 30-31 by 2600-2800 rpms. MP 292/509 cam with stock 1.5 rocker arms. BG Demon 850 with #85/93 jets and a 3.5 PV. In gear idle vacuum was 8-9". It detonated in cool weather but was worse in warm weather. I tried mixing in some 110 octane leaded fuel and ALL of the detonation was gone. On a 50/50 mix of 110 and 91, it did not knock either. I didn't want to rely on race octane to drive the car, so I started looking for ways to make the engine less likely to detonate. I could have pulled the engine and installed dished pistons, but many people thought that the '509 cam was too small for an engine with nearly 500 inches. A bigger cam with a later intake closing event was suggested many times. Before any cam swap was done, I switched to 1.6 rocker arms, thinking the additional lift might help. It reduced the cranking compression a few points, but I was still between 185 and 191 psi. I went with a Lunati solid flat tappet with 261* INT, 271* EXH @ .050, .556/.578 lift and a 108 LSA. The intake closing was figured to be 11 degrees later than the 509 cam. I degreed the cam in at the 106 centerline according to the cam card. While the carb was on the bench, I changed the jets and PV from #85/93 to #86/94 and from 3.5 to 6.5. I set the timing to a conservative number for the break in: 16 initial, 30 total with NO vacuum advance. The engine ran warm on cam break in and started to boil the fuel at 15 minutes. After cooling down, I ran it again until the fuel boiled again. I didn't know at the time that it was running extremely lean, making the engine run hotter than it should. I haven't used a fan shroud on the car in the 12 years of running big blocks but I figured it was time. I fabbed up some brackets and mounted one. During a test drive, the car detonated at anything over 1/2 throttle. I was confused because the timing was set where it should be fine. For testing purposes, I backed it off until it wouldn't ping at WOT. this turned out to be at 6 initial and 20 degrees total. I knew that something was wrong when it knocked at more than that. I suspected a lean condition. Yesterday I installed an AEM wideband UEGO Air/Fuel sensor and guage. I Think it reads from 11.0 to 17.0. I made no adjustments to the carb but DID reset the timing to 19/33. The vacuum in Park at 1100 rpms was around 9.5 and the IN GEAR @ 800 # was about 4.5". I backed out the idle mixture screws to a full 2 turns out from bottom. manifold vacuum went to 10+ in park and 5 in gear. The guage moved to 14.5+/-both in Park and in gear. When I eased into the gas while in gear, the guage went beyond 17.0 lean. I thought that since my vacuum reading was BELOW the # on the Power Valve, I switched to a 3.5 PV. THIS didn't change anything while in Park but now it would go 17.0+ when in gear. I thought that a jet change would help so I switched to #88 primary jets. Now the in gear idle came back down to 16.0+/-. It still went past 17.0 when I eased into the throttle. I have not driven the car with the guage in place to see how it is on the street. I HAVE sprayed Brakleen all around the base of the carb, the various vacuum ports, the intake ports and so far I have found no vacuum leaks. I plan to have a helper watch the guage as I try again. If the guage bumps at any time, maybe I'll find a tiny leak somewhere. I only have two square bore carbs here I can test with, a Holley 600 and a 750. I have ThermoQuads too, though the adapter would make it impossible to close the hood with an air cleaner on.
For the record, I do have a decent understanding of the workings of a carburetor. Its just that I have been so frustrated lately I have been forgetting things.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492873
09/02/13 04:50 PM
09/02/13 04:50 PM
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Joined: Feb 2005
Posts: 4,314 Prospect, PA
BSB67
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master
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Prospect, PA
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Okay. Here is a shorter version of what you said: Quote:
The 440/493 made decent power and idled well with the previous combo. It was:
•500” RB •Edelbrock aluminum heads, unported •2" TTI headers and a 2 1/2" exhaust system •MP electronic ignition/ chrome ECU/ 14 degrees of total advance. •I used to set it at 16-17 degrees with it advancing to 30-31 by 2600-2800 rpms. •MP 292/509 cam with stock 1.5 rocker arms/switched to 1.6 adjustables before cam switch. •BG Demon 850 with #85/93 jets and a 3.5 PV. •In gear idle vacuum was 8-9".
It detonated in cool weather but was worse in warm weather. I tried mixing in some 110 octane leaded fuel and ALL of the detonation was gone. On a 50/50 mix of 110 and 91, it did not knock either. I decided on a bigger cam with a later intake closing to reduce cylinder pressure.
Changes: •Lunati solid flat tappet with 261* INT, 271* EXH @ .050, .556/.578 lift and a 108 LSA. The intake closing was figured to be 11 degrees later than the 509 cam. •changed the jets and PV from #85/93 to #86/94 and from 3.5 to 6.5
I degreed the cam in at the 106 centerline according to the cam card. I set the timing to a conservative number for the break in: 16 initial, 30 total with NO vacuum advance. The engine ran warm on cam break in and started to boil the fuel at 15 minutes. After cooling down, I ran it again until the fuel boiled again.
During a test drive, the car detonated at anything over 1/2 throttle. I was confused because the timing was set where it should be fine. For testing purposes, I backed it off until it wouldn't ping at WOT. this turned out to be at 6 initial and 20 degrees total. I made no adjustments to the carb but DID reset the timing to 19/33.
The vacuum in Park at 1100 rpms was around 9.5 and the IN GEAR @ 800 # was about 4.5". I backed out the idle mixture screws to a full 2 turns out from bottom. manifold vacuum went to 10+ in park and 5 in gear. The A/F gauge moved to 14.5+/-both in Park and in gear. When I eased into the gas while in gear, the guage went beyond 17.0 lean. I thought that since my vacuum reading was BELOW the # on the Power Valve, I switched to a 3.5 PV.
THIS didn't change anything while in Park but now it would go 17.0+ when in gear. I thought that a jet change would help so I switched to #88 primary jets. Now the in gear idle came back down to 16.0+/-. It still went past 17.0 when I eased into the throttle. I have not driven the car with the A/F guage in place to see how it is on the street. I HAVE sprayed Brakleen all around the base of the carb, the various vacuum ports, the intake ports and so far I have found no vacuum leaks. I plan to have a helper watch the guage as I try again. If the guage bumps at any time, maybe I'll find a tiny leak somewhere. I only have two square bore carbs here I can test with, a Holley 600 and a 750.
Here are a couple of my take-aways: 1) the Carb idled okay before, so it is probably not broken. 2) The carbs primary circuit may have been lean in the past causing your detonation. 3) If you did not have a fuel pressure gauge before, It too could have caused a lean condition causing ping if it were too low. 4)at 190 psi, you were on the edge but should be doable w/ pump gas. 5)Some Brakleen are not flammable, use a carburetor cleaner,
Try these and report back:
Choke the carb and see if engine rpm picks-up. Check ignition timing in neutral and in gear.
Also, What torque converter do you have? The in gear rpm might need to be set higher than 800 rpm with the new cam
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Re: Cam break in is done!....Now more questions!
[Re: BSB67]
#1492874
09/02/13 05:33 PM
09/02/13 05:33 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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OP
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Posts: 18,493
Granite Bay CA
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Quote:
Okay. Here is a shorter version of what you said:
Quote:
Here are a couple of my take-aways: 1) the Carb idled okay before, so it is probably not broken. 2) The carbs primary circuit may have been lean in the past causing your detonation. 3) If you did not have a fuel pressure gauge before, It too could have caused a lean condition causing ping if it were too low. 4)at 190 psi, you were on the edge but should be doable w/ pump gas. 5)Some Brakleen are not flammable, use a carburetor cleaner,
Try these and report back:
Choke the carb and see if engine rpm picks-up. Check ignition timing in neutral and in gear.
Also, What torque converter do you have? The in gear rpm might need to be set higher than 800 rpm with the new cam
Your summary is better than mine and 100% accurate! * I have no choke on the carb, but when I put my hands over the throat at idle, it changes nothing. I sprayed Ether and Brakleen (GREEN can) down the throat, the idle speed does increase. * Ive had a guage in the fuel line since installing this carb. It is pretty consistant at 6 psi at idle, dropping only slightly during sustained 3000+ rpms in Park. * I have not checked cranking PSI since the cam swap. It is probably lower than the 190 number now. * I will try checking the timing when shifting from park to drive. * I am going to have Jeff watch the guage as I spray carb cleaner around everything again. * The torque converter is a 9 3/4" unit with a stall of just under 3000. I just came back from the store with some carb gaskets and some Brake cleaner. I probably have some carb cleaner here I can try. I also have small Propane and Mapp gas cylinders I could use.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492875
09/02/13 06:02 PM
09/02/13 06:02 PM
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Joined: Feb 2005
Posts: 4,314 Prospect, PA
BSB67
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master
Joined: Feb 2005
Posts: 4,314
Prospect, PA
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* but when I put my hands over the throat at idle, it changes nothing. This means that you are not doing it correctly, either it will rise in rpm slightly, then die (vacuum leak), or it will instantly die like turning off the key (no vacuum leak). Do it again until it dies. I sprayed Ether and Brakleen (GREEN can) down the throat, the idle speed does increase.
* Ive had a guage in the fuel line since installing this carb. It is pretty consistant at 6 psi at idle, dropping only slightly during sustained 3000+ rpms in Park. Okay. But to be clear, any fuel pressure in neutral is probably enough. For eliminating any possible lean at WOT fuel pressure needs to be about 4 psi at your power level and std inlet orifice.
* I have not checked cranking PSI since the cam swap. It is probably lower than the 190 number now. Put this on your list of things to do * I will try ????I don't understand. Friend in the car-foot on brake. You get a measure of the timing in neutral, then have him put it in gear at idle, and measure again. Don't do anything else until you have done these two things checking the timing when shifting from park to drive.
* I am going to have Jeff watch the guage Be clear, what gauge? Fuel pressure?, gas gauge, vacuum gauge. if you mean air to fuel ratio, A/R will work, as I spray carb cleaner around everything again. Not sure what you learn from this * The torque converter is a 9 3/4" unit with a stall of just under 3000. The smart torque converter guys need to comment here. It sounds possibly too tight for the in-gear idle you might need for that cam, I don't know. The guys with big cam experience sould know what is a reasonable in-gear idle rpm should be. What is the advertised durations on that cam?
I just came back from the store with some carb gaskets and some Brake cleaner. I probably have some carb cleaner here I can try. I also have small Propane and Mapp gas cylinders I could use.
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Re: Cam break in is done!....Now more questions!
[Re: BSB67]
#1492876
09/02/13 07:49 PM
09/02/13 07:49 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Granite Bay CA
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More Updates:
* The timing jumps a bit while the engine is running, fluctuating about 3 degrees. I average the sweep to the middle. When at idle, it is at 19. When shifted into gear, the timing stays the same. * The carb HAD a choke, but I removed it along with all of the associated linkage. Putting my hands over the air horn does not form an effective seal. * I had Jeff in the car as I sprayed Brakleen around all possible vacuum entry points. I had him watch the Air/Fuel guage. The only time the guage responded was when I sprayed into the carb throat. No leaks at the baseplate, vacuum fittings, PCV, throttle shafts or anywhere along the intake ports. ******************************************************************** I put on a stock Holley 750 VS from another car. The vacuum numbers came up a bit. I got 11.5" in Park @ 1100 rpm and almost 7.0 in gear @ 850. The A/F numbers with the 750 impressed me. Idle: 13.8 to 14.2 In gear: 14.2 to 14.6 In gear w/pwr brake: 13.8 to 14.5.
This at least tells me that the 750 is in the range of tuning. The 850 keeps going totally lean when any load is applied off idle.
The 1000-1100 idle is set where it was before the cam swap. I only set it back there to have a baseline. When put into gear, The car doesn't try to pull away at that speed. I can raise it even higher if need be. I thought that the idle speed is supposed to be set as low as possible while not being lazy to respond. If it idled at 1500 or more, it seems like it would "diesel" on shutdown.
Last edited by Frankenduster; 09/02/13 08:28 PM.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492878
09/03/13 02:44 AM
09/03/13 02:44 AM
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Joined: Aug 2003
Posts: 6,301 colorado
a12superbee
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master
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Posts: 6,301
colorado
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This A/F meter/gauge thing looks to be the shizzle when it comes to carb tuning. Hard to believe a decade ago the idea of home use would have been pure fantasy. Now I want one. Good job on getting within striking range.
I can't afford this.
mark
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492880
09/03/13 08:45 AM
09/03/13 08:45 AM
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Joined: Jan 2003
Posts: 5,443 Indiana
YO7_A66
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Posts: 5,443
Indiana
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""With the bigger jets and CLEANER air bleeds, the A/F ratios are MUCH better. Idle in park: 13.0 to 13.8 Idle in gear: 12.8 to 13.5 In gear Pwr brake 12.0 to 12.9.""
- That is a much better starting point. Now you can take it for a drive and take note of your A/F readings at 30mph/40mph/50mph/60mph or what ever you choose. These A/F readings will help you tune your transition and your jetting for cruising.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: Cam break in is done!....Now more questions!
[Re: Dodgem]
#1492882
09/03/13 12:01 PM
09/03/13 12:01 PM
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Joined: Oct 2003
Posts: 3,698 NE Oklahoma
Von
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NE Oklahoma
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Didnt read every post word for word...but I didnt see any reference to getting the timing right before making all of these carb changes??
You have to get the initial timing right or everything else is pissin in the wind.
Have you checked put the vacuum gauge on it at idle and cranked more initial in it until it stops making more vaccuum? The motor will tell you how much it wants for initial.
Im sure that cam will be in the mid 20s to 30s at idle. Then you will have to limit the total to 34-36ish.
Get the timing right, then start playin with the carb.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Cam break in is done!....Now more questions!
[Re: Von]
#1492883
09/03/13 02:53 PM
09/03/13 02:53 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
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Posts: 18,493
Granite Bay CA
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Quote:
You have to get the initial timing right or everything else is pissin in the wind.
Have you checked put the vacuum gauge on it at idle and cranked more initial in it until it stops making more vaccuum? The motor will tell you how much it wants for initial.
Im sure that cam will be in the mid 20s to 30s at idle. Then you will have to limit the total to 34-36ish.
Get the timing right, then start playin with the carb.
Interesting.... I did NOT try advancing the timing at idle any more than I already have. Are you saying that instead of having a 14 degree advance where I set initial at 19 and the total ends up at 33, I should narrow up the total curve? In other terms, an initial of mid 20s with an "all in" of say mid 30s? Wouldn't this make the engine very hard to start?
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