Counterweighted crankshaft

[jibby212]

I have been on the engine search for an O360 or IO360 for my RV7. I have found 2 in my price range, the first one is an A2F with solid crankshaft and the second is a A1F6 with counterweighted crankshaft. Both claim to be 0 TSMO. The A1F6 seems has new cylinders but is across the country. I am keeping it simple so it will be fixed pitch. The counterweighted crankshaft scares me a little, its adds weight and strays from the simple objective. I have found some info on pros and cons but not a lot, I am reading they do not like rapid throttle changes. Any experts on this subject out there?

[Carl Froehlich]

The solid crank would be a deal breaker for me. While you might want a FP prop now, you may change your mind after a few hundred hours (I did).

The IO-360 sounds like a better deal assuming it is at a massive discount below the Van?s IO-360-M1B.

Carl

[Bevan]

Not an expert here but one data point.

I bought a mid-time 0-360-A1F6 from across the country. Other than being a little heavier (and possibly a little smoother), it doesn't seem any more complex. It can of course be configured for FP or CS prop.

165 hrs on my airplane so far with this mid-time engine. Compressions are still high 70's, filter examinations look good, runs smooth. CHT's are all in low 300's with a spread of less than 30F. It is now fuel injected and running P-mags.

Bevan

[Bevan]

Originally Posted by jibby212

I am reading they do not like rapid throttle changes.

Is it rapid throttle or RPM changes? Does engine start and shut-down not constitute as rapid RPM changes?

Bevan

[ccsmith51]

I had an O-360-A1F6D on my RV-4, with a Sterba wood prop. It was very smooth and reliable. I flew tight multi-ship formation with it, necessitating rapid throttle changes, and never had an issue.