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Question on piston?

#1

U

unioncreek

I'm overhauling my B&S Intek 17.5 hp, 31C707 engine. About a year ago the two brass screws came out of the throttle plate and went through the engine. The piston has dimples all over it. I removed the rings today and the top ring was very hard to remove, in fact I broke it a couple of times. I want to measure the width, but can't find out what it should be. If the ring groove has been narrowed by the piston beating the screw on the head can I just chuck it up in my metal lathe and bring the groove width back to specs?

Bob


#2

S

SeniorCitizen

unioncreek said:
I'm overhauling my B&S Intek 17.5 hp, 31C707 engine. About a year ago the two brass screws came out of the throttle plate and went through the engine. The piston has dimples all over it. I removed the rings today and the top ring was very hard to remove, in fact I broke it a couple of times. I want to measure the width, but can't find out what it should be. If the ring groove has been narrowed by the piston beating the screw on the head can I just chuck it up in my metal lathe and bring the groove width back to specs?

Bob
Click to expand...

Possibly if you have a 4 jaw chuck. Al pistons aren't normally round until they reach close to operating temperature.


#3

T

Tinkerer200

Have you taken pcs. of the broken ring and raked around the ring groove repeatedly both ways? I think you can clean it up that way. I would smooth off any sharp points on top of piston to prevent detonation.

Walt Conner


#4

S

SeniorCitizen

The first I ever used a manulathe was on a 1959 ford engine the dealer had screwed up by lapping the valves. Top rings in about 6-8 pieces, IIRC , from slapping in the grooves and rings below the top ring were in lesser pieces. Oil ring not affedted. The grooves had to be widened to accept a spacer with the std. ring.

Attached link of lathe and piston modification.

https://youtu.be/fKdnZbkHwLM

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