Looking for some assistance. I have a Ford 302 and a 54 mercury. Haven't had the car long. It Ran great when I first bought it. The next time I tried to drive it there's a slight pop or sputter the carb from a dead stop. Runs fine at idle in park. Revs up great. However hen I put it in drive and go to accelerate it'll pop once or twice. It'll even die if I don't feather the gas just right. If I let off and gas it past that it runs great. No other issues unless I'm coming off a dead stop. Has a new clear fuel filter that is always full so I do think It's a fuel pump issue. I even swapped the carb. Went from a 600 cfm edelbrock to a 500 cfm edelbrock with a noticeable gain in acceleration. But the issue persists Has pertronix ignition for what it's worth Just closed her down for the evening after the carb swap. Going to check for vacuum leaks tomorrow. Any other tips or information are greatly appreciated.
A few questions- What intake and heads are on the motor? What type of gas are you using, E10 or 15? Has the ballast resistor been removed out of the ignition circuit? Edelbrock performer or AV2? Running a vacuum advance on the distributor?
Premium pump gas 93 e10 Performer intake Not sure on the heads. They look stock. Im new to Ford motors. Appears to be a early 80s 302 No ballast Currently has a AV2, But I have the same issue with the 1406 carb. Ruining vacuum advance
Which vacuum port are you using for the vacuum advance- manifold or ported? Is the distributor vacuum can single or dual ports? I would also look at the carb base vs. manifold. Some of the AV2 models don't match the intake very well (even with Edelbrock manifolds) and vacuum leaks will occur. Flat tappet or roller cam? An easy way to tell the year of the motor is to look at the dipstick- Ford put the dipstick in the block in 83 or so.
A worn timing chain jumping a tooth. Ignition and cam timing will be retarded. Cranking the starter with ignition disconnected, fuel-air vapor may be seen blowing up out of the carb.
I agree, that could be the problem. With the engine not running and air cleaner off have a look down the carb and make sure it’s getting a full pump shot.
I thought sure it was accelerator pump. That's why I did the carb swap. Seemed unlikely to have the same issue with both carbs. I will be checking things closer after work today. The timing chain crossed my mind as well
Only if the other carb was sitting around on the shelf for a few months or longer. It’s always the first think I check for as it only takes a minute to do.
One of those problems where you need to determine if the problem is carburetion or ignition. Like RmK57 said, take a look down the carb with the engine not running. I like to manually open the throttle full and watch the accelerator pump discharge. It should be steady through the whole travel of the pump piston. The best way to check ignition output is with a scope. However, if you pull the coil wire from the cap and hold it about 1/4 in away from say the intake manifold, you should get a good, strong spark while cranking the engine over. Next take a plug wire and do the same thing. You will probably need to use something, like a spark plug center electrode, to fit in the plug socket. The spark should be able to jump 1/4 in at least. What you are checking is available voltage. The ignition needs to have enough reserve (available voltage) to take car of required voltage. When you quickly open the throttle, required voltage spikes for an instant. If you don't have enough available voltage you can get a miss-fire for that instant.
I appreciate that information. I'll take a look at that tonight. I do have new plugs and wires on the way. From what I can tell the car hasn't had much maintenance for at least 7 years based off the information I got from the previous owner
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