Changing jets/rods for the first time.
#1102721
10/27/11 03:31 PM
10/27/11 03:31 PM
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Joined: Aug 2003
Posts: 4,481
Mesa, AZ
Pat_Whalen
OP
super gas
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OP
super gas
Joined: Aug 2003
Posts: 4,481
Mesa, AZ
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So I'm finally trying to commit to one way or another of fuel delivery. I was leaning heavily toward a TQ for mileage (daily driver 440) but I'm torn between that an the venerable Edelbrock 1405 that is on there now.
I've got a wideband O2 sensor in my passenger side exhaust so I can sort of get a sense as to what's going on.
Truck does not seem to like idling cold. Once it's warmed up and idling in park at around 750rpm (16" vacuum), I'm reading right around 13.5 on the O2 gauge. Fiddling with the IMSs do nothing for that number.
In gear, idle drops down to ~675 rpm and the O2 gauge has a slight increase to around 13.8-14
Stabbing it from a dead stop results in a heavy bog, missing, and the gauge spikes to around 17-18.
If I ease into heavy throttle, the gauge will drop down into the 12s.
Cruising, the gauge is around 12.8-13.
I imagine it's not a very straight forward answer but are these numbers the result of an improper configuration of jets/rods?
I understand what the edelbrock manual is talking about with the calibration reference chart. I'm just having a hard time understanding which way I should go- leaner or richer?
Any help would would be greatly appreciated. If it comes down to me having to purchase the calibration kit, I'll grab one from summit.
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Re: Changing jets/rods for the first time.
[Re: Pat_Whalen]
#1102722
10/27/11 03:51 PM
10/27/11 03:51 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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I work on the 1405 all the time. It sounds like you need a new acc pump seal. I drove mine for 20 years without the choke hooked up and just kept pumping the gas when it was cold. This past fall I stuck a cable under my dash and hooked it up after 20 years. Now my car will idle right away when cold. I do have to play with it if I drive it right away. It'll go fine cold with the chock off, if I leave it on it when driving it restricts it enough to notice it. I pull the chock out at intersections when IU have to stop cold and open it when I get going. Now I change the jets and needles all the time. Earlier this past summer we went to Pikes Peak and then Las Vegas in 110 degrees temp. Drove my 340 to 14100 feet, that carb better be lean to make it all the way to the top! So I went real lean before I left Cincinnati, 4 steps I think and gave it more timing. Then When I came home I switched back to 1 step lean where I usually have it. Then about a month ago when the air got cool I change needles to 1 step rich which my motor wanted and it runs real good in this cool air. Some of those seals/cup for the acc pump do not work, you should change yours first and see if it get's rid of your bog. Being on a 440 yours seems like it may be lean, mine is on a 340.    Yup that's dirt, I cleaned it out with a paper towel.Then replaced my rubber hoses is what I think it was. Hose was 10+ years old. 
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Re: Changing jets/rods for the first time.
[Re: Pat_Whalen]
#1102723
10/27/11 03:55 PM
10/27/11 03:55 PM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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You will get different opinions on what to tune in what order, but this will get the ball rolling for people to judge.
A) In D A/F ratio (auto)
B) Cruise A/F (20mph to 75mph or so)
C) Light to Medium Accleration (no secondaries)
D) WOT
""Truck does not seem to like idling cold.""
- Try mid 12's on initial cold start, then is should creep up to your N A/F reading in the mid 13's as it warms up.
""Once it's warmed up and idling in park at around 750rpm (16" vacuum), I'm reading right around 13.5 on the O2 gauge.""
- You will find different opinions on what is rich and what is lean. What I have found out is that you must first find out if you are running gasoline, E10, or E85. Once you know this, then you will have a reference as to what your stoich should be. The 13.5 is a good start on your N reading but the more important reading is your in "D" A/F since you have an auto car. Once you have the "D" A/F reading where you want it, then your N A/F reading will be whatever it is. I have found it to be slightly richer.
""In gear, idle drops down to ~675 rpm and the O2 gauge has a slight increase to around 13.8-14"".
- This number looks good too as long as you have your highest vacuum reading at this A/F reading. Just tune for the highest vacuum reading in D and then reference the A/F reading.
After you have the in D A/F worked out (which you are fairly close arleady), then work on your cruise A/F number (B above).
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Changing jets/rods for the first time.
[Re: scratchnfotraction]
#1102727
10/27/11 05:19 PM
10/27/11 05:19 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
Quote:
Thanks for the great input guys 
Just so I'm clear, idle A/F is accomplished via the IMSs. Cruise A/F tuning is accomplished via the rods and jetting? What gets changed in what order? Does changing rods/jetting change cruise or heavy throttle? both?
THanks. Trying to wrap my head around carb theory after I started most of my automotive life adding EFI to carbed applications 
dont forget you have springs that lift the neddles out of the jets before swaping jet and needles around  they have larger squrters also for more tuning.
my 400 dialed right in with my 1405,have to play with it just a little when cold but cleans right up at 180*.
holds 20" of vac in N at 850 rpm,drops to 18" at 750 rpm in D
has a slight ping on cheap gas and a WOT pull
IIRC,I have the timeing set just a hair of the timeing tab..12-14 I estamate eyeballing with the timeing light.
I got a few extra parts with a carterbroke carb I got from dragula if you need some springs or larger squrters and couple extra needles?jets also. LMK
Good points, Yes make sure the needles are down at idle. Easy to check with the covers out of the way at idle. I had to use lighter springs to hold my needles down at idle so I could tune it.
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Re: Changing jets/rods for the first time.
[Re: Pat_Whalen]
#1102728
10/27/11 05:54 PM
10/27/11 05:54 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I'd get the car on a level surface and run it a minute then pull the rods/top & want fuel level even with the notch in the flat metal float baffle on each side. Dry float setting is 7/16". Fix accel pump so you have immediate tip in when you touch the throttle. Assuming the original springs it came with are still in there & see the eddy site for what in hg they are and hookup a vacuum gauge to the front dr base port and run it with a rubber line to a vacuum gauge taped to your windshield to note the in hg that it bogs at. Need to use the manual choke letting it off gradually during warmup which may take 10-15 minutes or so or it will bog and force you to use more throttle which dumps a raw AP shot in to compensate which is never good for the cyls/rings. If it can be converted to an automatic choke like the 1406 I would suggest it and lightly closed at 70 deg F is a good baseline. I'd get that squared away then exp with a strip kit. I know my 1406 was pretty lean and that's on a 318 so I'm sure it'd be leaner on a 440 assuming the 1405 manual choke version is factory lean also. I'd get this carb squared away then you'll be in a better position to decide if you want to invest $$$ in a carb change and yes a properly set up TQ is a killer carb. & if you go that route it'd be nice if your intake is a spreadbore. EDIT I think the choke/A/P probs are (mainly) what's hurting your mileage tho mains could very well be too lean
Last edited by RapidRobert; 10/27/11 06:04 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Changing jets/rods for the first time.
[Re: RapidRobert]
#1102729
10/31/11 07:33 PM
10/31/11 07:33 PM
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Joined: Aug 2003
Posts: 4,481
Mesa, AZ
Pat_Whalen
OP
super gas
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OP
super gas
Joined: Aug 2003
Posts: 4,481
Mesa, AZ
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Thanks again for all of the help felluhs.
Figured I'd do a little more digging into the carb.
Trying to read these jets is a little daunting seeing as it's pretty obvious someone didn't use a correctly fitting flathead to remove/install them. And I'm working with 27 year old 20/15 eyesight here and it's still a bit of a stretch.
Anyway, what seems odd is that not only are the jets not the same side to side, it appears the rods are also not the same size.
Here's what I've got:
---------Pass Side-------------Driver's Side------
Sec. Jet---395(?)----------------400
Pri. Jet----395-------------------400
Rod-------"7547"---------------"18-485"
The only thing that seems consistant from side to side is the step-up spring. There is no color on it, but it's got a lot of coils, thinner gauge wire. Not sure what size that is.
It looks like someone, at some point, may have rebuilt this and didn't know to put the correct jets back in the correct spots. I hope this is a glaring problem and correcting it will get me back where I need to be.
I know the edelbrock manual has the stock configuration for the carb and it lists the stock primary jet and rod configuration, but what about the secondary jet? I'd feel much more comfortable just buying new jets and rods so at least I can read them and know they are the right size.
Thanks again for your time and help.
Last edited by Pat_Whalen; 10/31/11 07:35 PM.
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Re: Changing jets/rods for the first time.
[Re: RapidRobert]
#1102730
10/31/11 08:18 PM
10/31/11 08:18 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
I know my 1406 was pretty lean and that's on a 318 so I'm sure it'd be leaner on a 440 assuming the 1405 manual choke version is factory lean also.
The 1406 is the lean economy model and the manual choke 1405 model was jetted more for performance from Edlebrock new.
Hell yea it's almost impossible to see those numbers on the rods and jets. I use a larger flat blade screwdriver to loosen/tighten and then a smaller to remove/install jets.
Use this magnifying glass to see the numbers and these cheap numbered drill set to compare jet sizes even if I can read the numbers. I have found many jet's with wrong numbers stamped on them, for all carbs.
The jet kit won't come with stock needles and jets, but has everything else and is almost necessary for tuning.
Stock/base jetting for a 1405 is 1428 jets, will say 120-400 on the jet.
Stock rod is a 7047 stamped on rod. Easy enough to check with a dial calibur. .070 thou on the thick end and .047" on the skinny end.
If you have 400 stock jets and 7547 rods...you are 2 steps lean in cruise mode and a little lean in power mode. I'd say way too lean for a 440 motor considering I run 1 step lean in the summer with my 340 with eddie heads and recently went 1 step rich for this cool fall air the car really responded well.
When I go to Pikes Peak and out west 6000+ or higher, I go with 24 on the reference chart which is like 2 steps lean both ways with more timing and less idle screw.
13000+ feet high
 
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Re: Changing jets/rods for the first time.
[Re: RapidRobert]
#1102732
10/31/11 09:51 PM
10/31/11 09:51 PM
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Joined: Aug 2003
Posts: 4,481
Mesa, AZ
Pat_Whalen
OP
super gas
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OP
super gas
Joined: Aug 2003
Posts: 4,481
Mesa, AZ
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It's amazing what happens when you have matching primary and secondary jets in the right place in the carb body 440 is running way better than it ever has. Fired right up cold, didn't have the loppy/miss sound to it and was idling much higher (~1200 rpm), an obvious indication that my original setup was way wrong. Cruising felt much smoother, although my O2 sensor still read mid 13's. Hammering the gas a couple of times resulted in a kick in the pants and the truck taking off (as much as it can- 3.23 gears and a 6000lb truck). One time out of 5 there was a slight hesistation, but it's nowhere near how terrible it was before. Right now I've got 400 (.100") primary jets and .073"x.042" rods in (from a 1406 I had sitting on a shelf). That puts me at configuration 23 on the 1405 chart. I'm not so much concerned with power as I am economy at this point, so I'm not sure which direction I'll go. I may try and get back to stock configuration and work from there based on vacuum, O2 readings, and mileage.
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