The Cessna 120-140 Association Forum

For you engine guys....

I got my parts back from the engine shop yesterday and am currently balancing the pistons/connecting rods/ring sets/piston pins/rod bolts/rod bearings/nuts/cotterpins in sets, so far the best I can do (in grams) is 1869gm, 1872gm, 1872gm, 1873gm. I cannot find what is the acceptable range in the overhaul manual or the latest Continental M-O manual but I think I'm pretty good so far. Any comments?

As a side note, much like Mac Forbes, I needed an accessory case, found a used serviceable that I had bushed. My old one looked OK to me but the shop fellow had a concern on a groove behind one of the pump gears.

Nothing like shiny painted/plated/polished engine parts to get you excited about summer flying...

Continental doesn't address balancing these engines. The individual parts are supposed to fall withing an acceptable range, and so you're actually doing more than is expected. Unless you're having the crank, rods and pistons dynamically balanced, (which is what I would do,) I wouldn't worry about it. (Randy may have a different take...)

Yes, the plan down the line is dynamic balance. Not much to work with on such a small spinner hub unlike the Lycomings.

The last engine I helped on was a C85 that we spent alot of time on weighing components, I couldn't help but notice how smooth their engine ran so I figured it may be time well spent on my engine.

I know some Lycoming drivers that spend extra time on their static balancing.

What I was referring to is dynamic balancing of the crank, rods and pistons as an assembly. It also involves balancing the rods lengthwise, big end to small end. I don't know to much about the actual process, but it can involve some removal of metal. It is internal to the engine.