Running rich

Running rich with black smoke from pipes on accel. Worse since headers on and sealed. Carb has not been right since OH, but not many miles on card. Eldebrock 600CFM. 4V. Thinks I should replace since car sat for 7yrs? Running Edelbrock intake, 513 lift cam and headers. Don't want to cook new engine!

Alan L

7 years is a long time for a carb to sit. How do the plugs look? Are they sooty? What about at idle, can you smell gas in the exhaust? How does the oil smell?

7 years is a long time for a carb to sit. How do the plugs look? Are they sooty? What about at idle, can you smell gas in the exhaust? How does the oil smell?

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did OH before installing. Seems worse after headers installed. now get condensation on cold starts, mostly rt bank.

So that I understand. It was running good when it was pulled. You did an overhaul on it. (what did you do?). Car was running but seemed to be running rich. You used the same carb that was on it but it sat for 7 years. You put headers on it and the problem seems to have worsened. Is that a good summary?

You have a pretty beefy cam in it hugh? What manifold vac do you have at idle (in park if it is an auto). What's the meter doing, is it steady or ? I don't know much about edelbrock carbs but on a holley they have power valves that open and add gas at a predefined vacuum. You can buy them in 1" increments. So if you have a power valve that comes in at, say 7.5" and a bigger cam that keeps your manifold vacuum low, it will cause it to open too soon or even 'all of the time'. I don't know if Edelbrocks have something similar. I am sure someone knows. Was that the cam that was in it before? What are the duration specs?

Edelbrocks tend to run rich, and they are a PITA to tune. I beleive you can change the rods to lean it out.. but I'd freshen up the carb at the least, possibly convert it to fuel injection . Ethanol does corrode carbs from the inside out, so it could be that the passages have expanded over time. It's also possible that the engine was running rich the whole time, but didn't smoke from the tails due to exhaust leaks. Is the car noticeably more sluggish on accel? Rich = bogging as the pedal goes down.

Eddys are very good carbs, I have several because they are easy to tune. It may be time for a kit for the carb. What does the rest of the engine build look like? What vaccum reading are you getting at idle? What kind of ignition? Water from the exhaust on start up is normal.

Andy

headers lose heat faster then cast iron manifolds, and they reduce the combustion chamber temperatures which might make the engine run richer due to unburnt fuel it could explain more condensation. usually with headers they tell you to advance timing 2-4 degrees.

I never understood that since if the problem is running rich and cold cylinder heads then actually retarding the timing 2-4 degrees would bring the temperature back up in the exhaust, but i guess since headers equal more power to people then advancing the timing having extra richness to exploit would mean more power from advancing the timing further.

the question is when is the motor running rich: only at idle?

if its only rich at idle you can adjust the mixture on the carb it should have some form of Idle air bleed or fuel screws.

a lot of people have this issue after installing headers, i hated them and went back to stock exhaust manifolds.

Running rich with black smoke from pipes on accel. Worse since headers on and sealed. Carb has not been right since OH, but not many miles on card. Eldebrock 600CFM. 4V. Thinks I should replace since car sat for 7yrs? Running Edelbrock intake, 513 lift cam and headers. Don't want to cook new engine!

Alan L

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Summit sells calibration kits for their carbs $37-$68 depending on carb number. There are at least a dozen 600 cfm carbs listed. You will need to know the number. You may want to get a top to base gasket as old as the carb is. The kits do work but it is an organized trial and error process, as most carb tuning is.

with that much cam lift and headers...i would think your carb is a bit small for that motor.....a 600cfm carb on a stock 4v cleveland is just enough...but..with that much cam and headers...i bet she is starving for air.....some folks think too big of a carb makes your car run rich...this is wrong..really..it runs too lean...lack of fuel....so if you put a carb that is too small it will run a its a tad rich...cause it needs more air for all that cam lift and headers you stuck on it..so its opening up on idol much father than it should too run.... the stock carb was 715 cfm's...i would recomend tring a holley 750 or eldebrock 750...im putting in a 525 lift on my..carb has to be a 750cfm or more..and i still have to play with the jets to up it a bit more...clevelands love to breath.

Also, what is your fuel pressure set at? Ebbelbracks tend to like 4-5 psi instead of Holley's 7-10 psi.