Fuel Problems
Thread Starter
Instructor
Joined: Sep 2001
Posts: 209
Likes: 0
From: Seattle WA
Fuel Problems
Great forum!! I've been finding all kinds of answers in the archives, but this is the first time I have posted. My freshly rebuilt Holly 750 vacuum sec. has this terrible habit of flooding the engine because of stuck needle valves. It has happened about 8 times in the last 2 months, typically it happens right as I am trying to start the engine. It won't start, smells like gas, and a quick look into the carb shows gas dripping down into the closed butterfly valves. It has happened also after a few hours of normal driving. The carb has dual gas feed, and it has happened on both the primaries and the secondaries (both one time). Luckly the problem can be fixed quickly by reseating the stuck valve(s). I have tried putting the old needle valves back in, with no improvement. I thought it could be a bad fuel filter, but it seems to be fine. I also tested the fuel pressure, and as far as I can tell it is ok (about 5-6). Thanks in advance for any help on this! Really need to remedy this dangerous problem.
Beige 79
Fully optioned (all working too, finally!)
Doug & Nash 4+3 overdrive, 3.55 rear end
383 Stroker, Brodix Alum heads, hot cam, headers, true dual exhaust, Performer Rpm intake, Holly 750cfm Vac Sec., MSD 6AL HEI, NO POLLUTION CONTROL!
Larger Front/Rear sway bars
Beige 79
Fully optioned (all working too, finally!)
Doug & Nash 4+3 overdrive, 3.55 rear end
383 Stroker, Brodix Alum heads, hot cam, headers, true dual exhaust, Performer Rpm intake, Holly 750cfm Vac Sec., MSD 6AL HEI, NO POLLUTION CONTROL!
Larger Front/Rear sway bars
Instructor
Joined: Jul 2001
Posts: 168
Likes: 4
From: central Washington state
Re: Fuel Problems (inqbus383)
inqbus;
I run a Holley 650 vacuum secondary on the 406 in my '73 and I have had what sounds like the problem you describe at least once. Fixed it the same way you did and it hasn't reoccurred so far. The only suggestion I can make is to double check that the floats are set correctly and that there's no way they could hang up or bind. Sometimes it's the very small things that can cause you problems. There is a gentleman on the board who has a terrific reputation for troubleshooting carbs that may have more insights. His name is Lars. Do a search for his posts and send him an e-mail. He may have some better suggestions.
I run a Holley 650 vacuum secondary on the 406 in my '73 and I have had what sounds like the problem you describe at least once. Fixed it the same way you did and it hasn't reoccurred so far. The only suggestion I can make is to double check that the floats are set correctly and that there's no way they could hang up or bind. Sometimes it's the very small things that can cause you problems. There is a gentleman on the board who has a terrific reputation for troubleshooting carbs that may have more insights. His name is Lars. Do a search for his posts and send him an e-mail. He may have some better suggestions.
