Hey Oldsguy!
Quote:
Originally Posted by Oldsguy
Mike, it sounds to me like you are on the right track. I wonder about the inconsistent vacuum. With everything plugged, except the advance cannister on the distributor I assume, you shouldn't have a leak. With a TH400 you would have a vacuum operated kickdown, that might be it, or the accumulator for the brake booster assuming you have power brakes. Like you said, it might be gaskets, or could be the throttle plate bushings on the carb. If the bushings are worn, you would have a vacuum leak that would come and go. Would also effect the carburetor performance too. One other thought might be a worn timing chain, have you double checked you timing? It might be jumping teeth.
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Thanks for the information.
Yesterday I found where someone had screwed a bolt into the intake where a pipe plug should have been used. It was loose. I applied the correct plug with some teflon tape. Then I discovered that the electric choke was wired into B+ for the ignition coil. I could make the quality of the idle deteriorate by plugging in the choke. I moved the choke power supply wire to another spot.
Bottom line is that the backfires through the carb went from about 20 Saturday night down to 2, so it's running a lot better.
I eliminated the brake booster and modulator when I plugged all those off. No difference in idle or manifold vacuum.
Good point about the throttle shaft bores. I had replaced the throttle shaft bushings in this carb, so the shafts are tight.
I'll look into valve train this weekend. I'll have to get some valve cover gasktets and an intake manifold gasket.
By the way, do you know what size that crank bolt is? I'd like to turn the engine over with a breaker bar to check my chain, but I don't think that I've got a socket that large. I'll need to buy one this week.
Best Regards,
Mike