My daily truck is OT as its only 42 years old. The issue I'm having is traditional though as no current mechanic i've talked to seems to be able to do diagnostics without a computer plug to work off of. The truck is a 72 binder that I just put in a 392 with about 20,000 miles. It ran great with efi and a 2 barrel intake. I bought it and a stock 4 barrel intake from a friend. I had a 650cfm edelbrock carb that was on a 350. it ran ok, but I had a local carb guy rebuild it. After re-wiring, new ignition, gaskets etc, the engine would only run for about 20-30 seconds, then die. I was able to set the timing to spec, (it sounds good) and thats about it. Removed the carb and found a lot of raw fuel in the intake. Had the carb gone through again, reinstalled with no improvement. I borrowed a spare 500 cfm edelbrock carb from a friend, it ran a bit better and longer, but wouldn't restart after running about 5 minutes. I pulled it and found fuel in the intake again. Enough that even without a carb, I turned it over and it ran for a few seconds. I'm running a stock mechanical fuel pump, so I did not use a regulator, but this is the only thing I can think of trying. Am I missing something else to look at? I would appreciate any advice as I am totally stumped.
Sounds like you are over powering the needle and seats , edelbrocks can only take about 6 lbs. of pressure . Check the fuel pressure at the carb
I was going to try that next. Would a stock mechanical pump put out more than that? The pump came off of the 304 that was in the truck with a 2 barrel Holley, I was afraid it wouldn't keep up.
could if the pump is at fault or the return line is plugged . I would check the fuel pressure and go from there
Check the fuel pressure. Don't bother doing anything else until you know what the fuel pressure is. Don't care what pump you have or where it came from or what it's supposed to do, all that matters is what it is actually doing and the only way to know that is to put a fuel pressure test gauge on it.
As said already, "Check fuel pressure". Your issue is a common one and has been discussed many times before here on the HAMB.
In your opening statement you say "e.f.i and a 2 barrel". Last I knew e.f.i. stood for Electronic Fuel Injection. By that I'm assuming you mean 2 port throttle body. If that's the case your running way to much fuel pressure. Like 31 Vick and others said, put a gauge on it. The Wizzard
The engine was in a buddies truck with an efi and electric pump. My truck blew up the 304, I am using that mechanical fuel pump which previously ran a 2 barrel Holley. I just rigged up a gauge that only shows 4 1/2- 5 psi, although it is bouncing a bit. I think I'll pick up a regulator anyways, maybe the pressure fluctuates too much.
I am hoping someone out there can help. I installed the regulator as suggested. It has made no improvement. I even dropped the pressure to below 3 psi ( as low as the reg would go) , it would run nice for about a minute, start to stumble and then die. I remove the carb and the intake has a puddle of fuel in it. I tried the smaller carb, same thing. I ran a carter electric pump, same thing. It's a factory dual plane cast intake. I had re painted it and saw no cracks or anything appearing damaged. The vac advance seems to be working fine, my timing is within a degree or so of factory spec. I have no power brake booster, all of the carb vac ports have correct caps, all of the intake vac ports have brass plugs except the factory PVC port which is being used. There is a stock cam, and like I said it runs great on startup, so I don't think it's an engine issue. What am I missing? Posted using the Full Custom H.A.M.B. App!
Have you checked the float levels? If you don't have an Edelbrock book, look online for the proper way to do it. Its not hard. If its not way off, set it lower than spec just to try it.
I had the carb rebuilt by a guy who has been doing it for decades. When I first had the problem, I brought it back to him thinking he had made a mistake. That was the first thing he checked, and confirmed they were set right and the valves were not sticky. The confusing thing is that it does exactly the same thing with 2 different carbs. Posted using the Full Custom H.A.M.B. App!
There is no return line, and it does the same thing with both the stock mechanical pump and the electric one. No difference either at the recommended 5-6 psi or as low as 3 psi Posted using the Full Custom H.A.M.B. App!
Have you checked the choke settings? Is the choke a manual or automatic? If automatic, is the choke coil on the carb or the manifold? If it's on the manifold, the linkage may be wrong for the carb. If there is raw fuel in the intake manifold, it's flooding for whatever reason. Flooding should not be that hard to remedy.
The carbs I tried both have stock electric chokes installed. I ran new wire from the " key on" position, and it seems to be working, although it doesn't run long enough to go off. The choke rotates and I have it set almost as lean as possible. Is there another way to lean out the mixture? The carbs both seemed to run fine on smaller engines. Posted using the Full Custom H.A.M.B. App!
If its not backfiring before it dies, look down the carb while its running and see if its dumping excess fuel before and after it stops. Im betting the carbs needle isnt closing on the float, or if its brass floats, it has a leak in it.
Well, I will open it up again to check, but the rebuilt one was thoroughly cleaned twice, and runs exactly like the old one I had on the shelf. I am running the stock glass bowl filter, and a disposable inline one ( brand new). Isn't this a bit unlikely since both carbs I tried do exactly the same thing? Posted using the Full Custom H.A.M.B. App!
Are the power pistons moving freely in their bores? Are the metering rods properly seated in the jets? The rod tips are easily damaged if not installed carefully. How much manifold vacuum do you have at idle?
Thanks for your input. Again because both carbs ended in the same result, I think it needs to be something different. The rebuilt carb was completely gone through twice. The second time he thoroughly checked the seating on the jets and double checked the seals on the power piston. I don't have a vacuum gauge installed. I was thinking there may be an issue with that. What amount of vacuum should I expect? I keep checking for leaks and haven't been able to find any. Could something cause too much vacuum? Could a vacuum leak cause a rich condition? The intake manifold gasket is just a light gauge steel, and I have always set them dry. Should I add some liquid gasket sealer? Thanks for any input at all Posted using the Full Custom H.A.M.B. App!
someone suggested this but..... peg the choke open (with a peg or whatever, if electric give it voltege till full open) with it at idle or just above,look down the throat, is fuel coming out of the main venturi (main fuel opening for want of better words), there should not be. if there is its float level or needle and seat. Have you adjusted the idle screw so it can idle?
I have had the choke wide open, and could not see fuel. It did not look like my holly or the tbi on my other vehicles where I can see a visible jet. The idle screw is set and it idles beautifully on startup. Right at startup, I can get good throttle response. As it starts flooding, it doesn't like it as much, but I only get to play with it about a minute or so at a time. Posted using the Full Custom H.A.M.B. App!
Do you have a ballast resistor in the ignition/coil failing...? those symptom's can be an ignition problem and excess fuel is not burning and puddling. Your troubles sound like what I went through just the other day, my ballast resistor began to fail when heated up after a few minute running in the driveway and sputter/die.
I am tending to agree, but I keep throwing money at this somewhat blindly. The one carb ran totally fine on both my caddy 472 and in my son's 350 Camaro. The other carb came off my friends 350, and they both have the exact same symptoms on this 392 that ran fine with EFI, and runs nice before it floods. I don't want to buy a new carb and find out it's a different issue all together. Could I somehow have too much vacuum? Posted using the Full Custom H.A.M.B. App!
I don't have a ballast resistor in this truck. It doesn't run long enough to get to temperature, much less get hot. All new under hood wiring. New points and a new MSD coil, all new wires and plugs, and they look ok, other than wet ( not really fouled) I have dried them off several times, and it fires off quickly when I start it up. Is there a way to measure the strength of a spark other than "it looks good"? I get a good signal on the timing light on all 8. Would poor ignition result in a visible puddle if fuel in the intake after only a minute or so of run time? Posted using the Full Custom H.A.M.B. App!
How big is this puddle? Since you can only get it to run for a minute, the intake probably isn't going to be warm enough to evaporate the fuel, so there will be some wetness below the carb. Under the circumstances (two known good carbs tried) I'd be looking elsewhere. Try a different coil, and use a ballast resistor. Put in a new, or known good condenser too.
The ballast resistor gets hot reasonably quick unrelated to the engine temperature because its reducing voltage to the coil. If you don't have a physical resister you might have a resistance wire for the same purpose (like early GM's). Anyways, check to see if you have 7+ or - volts at the coil. If you run a full 12 volts to the conventional coil you will burn it up. If you have 7 volts you should have a resister in the system that could be the problem.
The puddle looks like about a tablespoon on each side ( dual plane intake, right side higher than left) it appears more than " wet". The carb gasket also gets wet. Square bore 4 holes in intake, using a thick gasket with square hole (have also used a 4 hole gasket). I did damage the new condenser I had bought, so I reused the old one. I will change that and see if it helps. Posted using the Full Custom H.A.M.B. App!
timed to #8 ?? for IHC I had a 345 1972 and it ate carbs had a 2 barrel then went to a ford 2 barell for awhile both were hollys when it run good , it flew , run to winnepeg to stock car races TOWING TRAILER AND CAR with it 12 MPG FINALLY ethanol KILLED IT AND I HAULED IT TO THE JUNKYARD wish you the best of luck I loved that truck when it run good and put a lot of miles on it over 100K maybe you should scope it and check available coil voltage also in my IHC adventures 392 were not as fast as a 345 I got caught speeding going into Fargo ND at about 80 MPH and that was a 3/4 ton
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