My flathead is giving me some fits. Idles fine, but when given gas when in gear it cuts out like it was running out of fuel. as soon as you let off the gas it pick right up. It started doing this last weekend, but it was after about 5 miles of driving?? i made it back to the shop but cutting out the whole way. is it fuel or ignition? i have an electric fuel pump also with the stock 48 glass bowl pump. i am running 2 holley 94's, Fenton intake , Offy heads, 12 volt, 51` Merc engine. Does anyone have any suggestions?
Are you running power valves in the carbs? If so, what number? Are you accelerator pump levers still in the holes on the throttle arms? Does it do this when revving up in neutral or just when driving? Flatman
I would have to look on the power valves. it only does it when driving. the thing that is confusing is that it had not done it for the past several weeks and started last weekend the friday night before i was going to take my son to the Goodguys show. we made it up in the morning no problem. when it was time to go, i made it about 5 miles towards home and it started cutting out???
I'm running 97's so no power valves, but mine did a very similar thing last weekend. I have one of those cheap ass rotary dial fuel pressure regulators. Initially I thought it was water in the carbs, as I had just washed it. I turned that dial a couple times and reset it, so far so good. I'm guessing a chunk of trash was stuck in it? It idled fine and free revved fine, but under load it crapped out.
The immediate thing you should check is dirty fuel line/tank. It don't take much obstruction to cause it to cut out under a load/acceleration. My 52 F1 ran like that and finally I pulled the fuel line from the tank to the pump and ran a wire through it and it was full of junk, and ran real strong after I cleaned it.
You might check the lead in the distributor going to the points. The vacuum could cause it to lose connectivity when the plate rotates.
new fuel tank & line. I will check the dist next. it has a Mallory dual point/ no vacume advance. Is it possible to have the coil cause this? i did re-jet the carbs from 48 to 42's and i couldnt even get down the street with out the same problem. when i changed the jets the bowls were clean. i also have one of the cheap dial fuel pressure regs on it. i am thinking about putting a gauge on it and read the fuel pressure.
had an old chevy truck run like this once you could take off then it would die , cool off an restart , turned out to be a bad condenser
You got a resister on the coil? If not you may have burned up the points.Although it do sound like a fuel prob.
I'd say it's a carb problem. Letting up on the gas shouldn't affect the ignition. Can you nurse it up to cruising speed? The first thing that I'd look at is the accelerator pumps. Are they both squirting? It will fall on it's face if one or both are not squirting when you step on it.
I had that problem leaving the HAMB Drags last year. The car would idle ok, but as soon as I gave it gas, it'd sputter and die. Turned out to be a bad condenser. Prior to that I fought another similar issue that was carb related. It was caused by a shitty rebuild kit for one of my 94s. The rubber plunger had fallen off the end of the accelerator pump.
I'm with Beemer, all my old flathead days--"shooting ducks" we called it, was always due to that old shock absorber---The condensor!!!!-------Don
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