Chevy1,
I got a chance to work on the truck on Sunday. This is what I found out. I checked the throttle linkage and made sure there was enough free play and verified it was not binding. Next, I checked for vacuum leaks using the WD 40. I didn't find any and the idle remained the same when I sprayed the carb. vac. ports etc. I only have one vacuum line running off the carb which goes to the vacuum advance. The others have been capped off and are not leaking. I do have a power brake vacuum line coming from the manifold which showed no leakage either. When I pulled the vac. advance line, idle increased. However, when I put my finger over the vac. advance line, idle speed dropped significantly. Much more than when the vac. advance line is hooked up to the can. This may be normal, I don't know. With the vac. advance dissconnected, I checked the timing. Keeping in mind that I can't get it to idle lower than 1200rpms, the timing was 25 deg. advanced. I was able to back it down to app. 12 deg. before the engine started to stumble. At 12 deg., the idle speed went down to app. 950rpms. Using Horvath's suggestion, I also verified that the wire between the coil and distributor is not binding. I also checked the plugs. They were burning clean (no soot) I still don't understand why the idle increased so much just because I put a new harness on. Maybe I hooked up the first harness wrong and had been driving with it that way all these years. At this point, I lost. Any other advice would be greatly appriciated.
