I have a 42 GMC with a 228 engine installed. I'm having a few problems that I think all stems to the fact that the carb is to a 270. When I bought it the guy though the shifting problem was from the engine sitting since 1982 and still using the fuel left in it. It ran a little “Slow” but sounded good. I put new gas in, engine cleaner and oil cleaner. The engine ran a lot better but it’s still having this problem. I think it needs ran some more too clean out the system, it gets better every time I drive it.

Problems:

High idle, I know pretty obvious, but the question is; is there some kind of attachment that I can add that restricts air flow down to 228 specs? Or do I need a new carb?

Shifting up from 2nd to 3rd it takes some time after shifting to regain speed. Going from 3rd to 4th I have to have a downward slope to keep the engine from slowing and stalling even with the gas floored.

Down shifting from 5th down when I hit neutral the engine reved extremely high and I had to kill the engine, I thought pushing it into 4th would blow the transmission up.

I am going to post this in both engine forum and the driveline forum because it seems it may be relevant to both.