The Cessna 120-140 Association Forum

First flight on overhauled 0200A (Cessna 140) was able to make 2500 RPM but engine sometimes ran rough going through 2200 RPM.
Perhaps coincidental improvement with carb heat or leaning it out. it was a dry, cold, and clear day
Saw a post indicating that the manifold should be attached finger tight and castellated nuts should be used.
Mine is attached with steel locknuts and the studs do not have holes in them for a cotter pin. The correct lock-o-seal washers are installed.
The maintenance manual and parts manual I have access to indicate a castellated nut but perhaps there is a later version or SB?
Thoughts and thanks in advance

Probably the least likely cause of the issue. The problem with the steel lock nuts is that they often pull the studs out when you try to remove them. Sounds like the engine is not yet broke in. Could be sticking valves or tight ring fit.

Or that Marvel pepper box...

Too bad you can't slap a Stromberg on it!

6298 wrote: ↑Sun Dec 26, 2021 5:54 pm Probably the least likely cause of the issue. The problem with the steel lock nuts is that they often pull the studs out when you try to remove them. Sounds like the engine is not yet broke in. Could be sticking valves or tight ring fit.

Thanks Randy.
Just continue to run it and it will 'loosen up'?