429 won't accelerate
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429 won't accelerate
I have been having trouble with my 429 during acceleration. It wants to stall when starting from a stop. It is especially bad when the engine is cold. It has the original 2 barrel carb on it. I have tried adjusting the idle mixture and the changed the settings on the accelerator pump but it doesn't seem to matter. It idles well and the timing is set to 10 degrees. Compression test showed cylinders from 170 psi to 150 psi. Added oil to the 2 lowest cylinder and the compression came upto 165 psi. What else should I look at? It's in a 64 F100 with a C6.
Nick
Nick
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When I first got the truck 2 years ago the carb was leaking so I went and bought a rebuild kit and followed the directions. This is the first and only carb I have rebuilt so maybe I did something wrong. Should I try it again or is there something specific I should look at. I just replaced the accelerator pump diaphram last week and it didn't make any difference. It does smell like its running rich and I have tried adjusting different things and it doesn't seem to change much.
Post Fiend
Joined: Mar 2004
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From: Union, Washington
Take the air cleaner off. With the engine off, advance the throttle while looking down the carb and you should dee fuel squirt in to bothe throttle bores. No fuel or a very small or inconsistant stream means the accelerator pump is not working or maladjusted.
Post Fiend
Joined: Mar 2004
Posts: 6,056
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From: Union, Washington
Well your indications are a lean condition which is worse when cold points to either accel pump shot not rich enough or you need bigger main jets or the float level is too low (which will richen the mixture. What do you spark plug tips look like?
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When I just pulled the plugs to do the compression test the the first 2 on each side were pretty black and then the back 2 on each side were white/gray at the tip.
As far as I know its all stock from a 71 Marqui. Could it be in the ignition? I had thought the accel pump wasn't putting in enough gas so I moved the linkage to the top hole. That should put in more fuel. I think?
As far as I know its all stock from a 71 Marqui. Could it be in the ignition? I had thought the accel pump wasn't putting in enough gas so I moved the linkage to the top hole. That should put in more fuel. I think?
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Forgot to mention the jets. If its still stock could the jets become to lean when the engine wears?
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Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Yeah it could be a weak ignition. You need to check for cracked or broke vacuum hoses or a vacuum leak around the carb, causing a lean condition. The fuel today is not what it used to be, so the same amount of todays fuel might be enough. Then again if you haven't been running a good fuel filter you could have trash in the float bowl partially blocking the jets. But the float level being low can cause it to be to lean. In any case the carb has to come apart to elimate it.
Post Fiend
Joined: Mar 2004
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From: Union, Washington
You should always check and make sure all passages are clear. A can of WD-40 with the little red tube attaqched works real well for that. Make sure float level is correct and the accelerator pump linkage is in the right holes.
Laughing Gas
Joined: Nov 2003
Posts: 898
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From: southeren Oh
When I just pulled the plugs to do the compression test the the first 2 on each side were pretty black and then the back 2 on each side were white/gray at the tip.
As far as I know its all stock from a 71 Marqui. Could it be in the ignition? I had thought the accel pump wasn't putting in enough gas so I moved the linkage to the top hole. That should put in more fuel. I think?
As far as I know its all stock from a 71 Marqui. Could it be in the ignition? I had thought the accel pump wasn't putting in enough gas so I moved the linkage to the top hole. That should put in more fuel. I think?
If the plugs are black for 4 cylinders in one chambers and fine for the other 4 you have a carb problem on one side of you carb. The black ones are running rich obviously.
