The International Cessna 170 Association

n2582d wrote:Very interesting! I’m astounded by the technical talent so many of the members here have.

So if you’re milling the pistons to match valve pockets where do you remove metal to match piston weight? I imagine at the rpm these engines turn everything moving internally is matched weight-wise down to a fraction of a gram.

Gary, with your experience you must have seen the inside of an engine that has been balanced, there will be belt sander impressions on both ends of the connecting rods and crankshaft counter weights and the under side of piston dome will have very shallow drill marks. All very important, especially when you want to turn up the RPM like the engines in Arash's bikes.

I wonder what the dynamic balance on this is?

Probably measured in ft-lb!

hilltop170 wrote:I wonder what the dynamic balance on this is?

Probably measured in ft-lb!

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At the typical 1800-2000 RPM it hardly makes a difference (especially when compared to the steel prop some of them twisted)

hilltop170 wrote:I wonder what the dynamic balance on this is?

Probably measured in ft-lb!

C7042D9E-0A83-4425-BC6A-89DD9A12448D.jpeg

Richard, do you put lights on that at Christmas time?

Arish here is picture of a Stewart Warner Crank Shaft Balancer similar to the one the shop who did our balancing used. You can see the adjustments to the counter weights are made with a belt sander, I don't think any of our cranks were so far out that they had to take metal away by drilling. Our pistons did have metal removed from the underside using an end mill.

johneeb wrote:

hilltop170 wrote:I wonder what the dynamic balance on this is?

Probably measured in ft-lb!

C7042D9E-0A83-4425-BC6A-89DD9A12448D.jpeg

Richard, do you put lights on that at Christmas time?

Good idea John! It's in Del's shop in Mena, AR

Check this story out....(You'll have to scroll thru all the pics to get the full story): https://www.msn.com/en-us/autos/motorcy ... hp#image=1