I have a GTX that I picked up a few months ago, been working on it since. The problem is that it sometimes "runs on" when I shut it down, seems to do it after idling a bit such as running in the drive before I open the garage and pull it in. 69, 440, 4-speed.
The 440 build is uncertain, as the motor was done before I got it several owners ago. It is running an Edelbrock 800 AVS, Mopar Electronic Ignition. Cam seems stronger than stock but not by a lot. Carb and distributor are new. I have been through the carb twice to double-check floats, etc. Idle jets are stock. I am pretty sure of no vacuum leaks, I have checked it very thoroughly and am using a good carb gasket. Distributor is a stock style advance curve from Bouchillon Racing. Timing is 12 BTDC initial, 32 full in. Vacuum advance is not increasing timing at idle, only adds about 6 when called upon. Idle vacuum is 14 hg and reasonably steady. I use a vacuum gage to set idle, I think I have it set pretty well in that it borders on rich smell at the tail pipes (though maybe a "run on" condition is too lean?). Idle set at 830 rpm. Plugs are stock J11Y's. I have thought of going to J10Y's to see what happens. Pump gas.
The car runs very well. No hesitation, very responsive. I did play with more timing but at around 16 BTDC on idle I started hearing spark knock, and much more timing when driving made it too "jumpy', probably boarding on detonation. I did check TDC and it is OK. No idea of how the cam is degreed. Temp gage is stock dash unit, runs at the 1/3rd mark pretty consistently.
Long story. Any ideas? Cooler plug with today's pump gas? Still too lean at idle? Though it runs cool, it does seem to have a lot of engine compartment heat, more than I think is normal. Stock exhaust manifolds.
The 440 build is uncertain, as the motor was done before I got it several owners ago. It is running an Edelbrock 800 AVS, Mopar Electronic Ignition. Cam seems stronger than stock but not by a lot. Carb and distributor are new. I have been through the carb twice to double-check floats, etc. Idle jets are stock. I am pretty sure of no vacuum leaks, I have checked it very thoroughly and am using a good carb gasket. Distributor is a stock style advance curve from Bouchillon Racing. Timing is 12 BTDC initial, 32 full in. Vacuum advance is not increasing timing at idle, only adds about 6 when called upon. Idle vacuum is 14 hg and reasonably steady. I use a vacuum gage to set idle, I think I have it set pretty well in that it borders on rich smell at the tail pipes (though maybe a "run on" condition is too lean?). Idle set at 830 rpm. Plugs are stock J11Y's. I have thought of going to J10Y's to see what happens. Pump gas.
The car runs very well. No hesitation, very responsive. I did play with more timing but at around 16 BTDC on idle I started hearing spark knock, and much more timing when driving made it too "jumpy', probably boarding on detonation. I did check TDC and it is OK. No idea of how the cam is degreed. Temp gage is stock dash unit, runs at the 1/3rd mark pretty consistently.
Long story. Any ideas? Cooler plug with today's pump gas? Still too lean at idle? Though it runs cool, it does seem to have a lot of engine compartment heat, more than I think is normal. Stock exhaust manifolds.
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