strange probem (new engine/carburator)
Thread Starter
Pro
Joined: Jul 2010
Posts: 532
Likes: 1
From: new york city ny
strange probem (new engine/carburator)
Car starts fine (even in cold weather). I let it idle for a minute before I go for a drive.
Everything is fine to this point. I can even drive it 30 minutes without any problems, but when I step on it and do few WOT runs the car stalls on me when I am at the red light.
I have a/f meter and it basically tells me that after few WOT the car gets PIG rich at idle and dies. Its still good ad cruising and WOT, just wont idle without my foot on the pedal.
Any ideas.
S.
Everything is fine to this point. I can even drive it 30 minutes without any problems, but when I step on it and do few WOT runs the car stalls on me when I am at the red light.
I have a/f meter and it basically tells me that after few WOT the car gets PIG rich at idle and dies. Its still good ad cruising and WOT, just wont idle without my foot on the pedal.
Any ideas.
S.
Thread Starter
Pro
Joined: Jul 2010
Posts: 532
Likes: 1
From: new york city ny
Yes the carb was tuned by me based on Lars articles and a/f meter. Bigger jets, different side squirter..basic stuff.
It was great during summer time (no problems at all). Now this problem occurred.
S.
It was great during summer time (no problems at all). Now this problem occurred.
S.
Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
I believe your a/f meter has identified the problem. The power enrichment system is hanging up when hot. Sorry but I have never worked on a holley. Suggest you post with holley in the title to get input from guys who run them, or call them for advice.
Burning Brakes
Joined: May 2009
Posts: 1,232
Likes: 6
From: Tucson AZ
St. Jude Donor '12
Sounds like you're developing too much fuel pressure in the line at higher RPMs causing fuel to force its way into the bowl after the needle seats. Then you bring the RPMs back down and the bowl is overfull causing the at-idle loading up you describe.
If fuel pressure is not the issue, the needle and seat may have a weak seal allowing normal fuel pressure at higher RPM to overfill the bowl.
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Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
Vapour lock and percolation are 2 different things (although most people don't recognize this). You are correct that vapour lock results in a lean condition because the fuel pump cannot suck / transfer vapour.
Percolation is from too much heat and/or too volatile a fuel causing a rich condition (fuel vapour being forced out of the carb). Installing a heat shield between the intake and carb can often solve the former. In the old days when we were all running carbs, if you had a heat wave in normally cold temperatures, all kinds of cars could experience percolation since the refineries were mixing fuel with the RVP for colder temperatures.
Percolation is from too much heat and/or too volatile a fuel causing a rich condition (fuel vapour being forced out of the carb). Installing a heat shield between the intake and carb can often solve the former. In the old days when we were all running carbs, if you had a heat wave in normally cold temperatures, all kinds of cars could experience percolation since the refineries were mixing fuel with the RVP for colder temperatures.
Thread Starter
Pro
Joined: Jul 2010
Posts: 532
Likes: 1
From: new york city ny