I have a 41 GMC 1/2 ton. Turns easily but backfires like a cannon. The grease cup on the dist is right up agaist the side cover, it rocks easily, haven't touched the vacuum advance. It looks like there's a screw on a collar on the back of the dist shaft, is that to adjust timing? Any tips would be appreciated. thanks, Neil
does it back fire up thru the carb or out the exhaust? when ever it backfired thru the carb for me on my 40 228 it always ended up being a vacuum leak somewhere.
once i was driving along enjoying the ride when all of a sudden the engine shut down with no warning. after close inspection under the hood with no tools i noticed that the grease fitting for the dist was up against the side cover which i knew that wasnt the proper position it should have been. i guess i didnt have it tight enough and it spun until the cup stopped it but that was after a 50 mile ride. it would turn but no fire or sputter until i turned it back then it i got it to fire and set the timing using the vacuum gage i have on the intake manifold. depending how your dist and cap were orientated it may or maynot be correct but up against the side cover leaves no room for timing adjustment.
i would set it up static with TDC on #1 cylinder and with the flywheel and your rotor should be pointing to #1 plug wire. should run but with no popping unless you have a vacuum leak somewhere.
Now it's making sense, I checked number one and the flywheel, looks good. It backfires through the exhaust. It sounds like it's just in my dist. How do you loosen it to reset? The bolt to the right does not do it and the bolt on the left doesn't either. Is there a collar with a screw? Also where do you put the vacuum gauge and what should it be set at? Thanks for all your help, I see light at the end of the wind tunnel.
