Extremely rough idle.

[Custom/20]

Originally Posted by 72_swb

is it a flat tappet. When you said you checked the lifters did you pull them out? just curious.

no. I just checked to see if they were collapsed by pushing on the rockers and seeing if they went down. All are good. I have also checked the rocker travel and none of the lobes are flat. A combination of my timing being retarded and the carburetor being out of adjustment must have been my problem.

[Custom/20]

A little update. So i did a compression test and its still right around 150 on all cylinders except number 2 which is at around 110. I did get the timing diled in at 12 degrees before top dead center with advace unplugged and capped off at 800rpm. I let it sit for about 40 minutes and it starts right up and runs great. Im just going to pay attention to my coolant level and watch my oil pressure and tach for now. So far so good.

[LongBox]

Sounds good. Idling nicely, and you did not have to go into the engine. As for the low compression, the engine should run for many miles with one cylinder low, but it will never be quite as smooth as an engine with equal compression across all cylinders. Will not develop as much ultimate power, either, but probably not worth going into the engine until something else needs attention, and that could be many miles down the road.

If you are interested in further diagnosis of this problem, you could do a "wet" compression test in that cylinder. If you add a couple of squirts of engine oil through the plug opening, you can check the compression again. If it goes up significantly, it is an indication of bad compression rings. If it does not go up, it usually means a bad valve.