Re: Chasing Rough idle...compression?

Posted by Mike On 2011/5/27 18:15:36

Did some quick adjustments and testing yesterday (got dwell correct at 26*, believe point gap was .017)

Idled slightly better. Took the air cleaner off the carb after it was warm, choke butterfly straight up and down. Can adjust mixture screws in until it wants to die (more) but coming out doesn't make much of a difference. Adjusted time slightly after dwell, but never got vacuum above 12-13 with mixture screws or anything.

Interesting note? Before shutting it down just out of curiosity, i manually played with the choke. Closing it most of the way (maybe 1/4" air gap before closed?) brought the idle up slightly and smoothed right out. Idle was hanging at around 750-800 rpm when doing this, and running smoother than when the motor is just reved to 800 rpm when warm. Adjusting the mixture screws out to richen the mixture did nothing, so i shut it off and put it away.

Unless we bring timing into the mix (mech advance starts at 600 i believe, so 800 was there.) i'm really leaning towards the carb. I have to take the other manifold apart and reman it, the replacement carb is here. Within the next few weeks i'll do the manifold swap (very short on time lately) and we'll see for sure.