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Reusing 35 piston

renegade

New member
"tore down the engine on my 79

"tore down the engine on my 79 175hp rude because of low compression on one cylinder. plan to have it rebored. shop says to remove all pistons and send him the block only. can i reusing the old rings on the rest piston? also, on a separate subject, how much scuffing is acceptable on a piston before it cannot be reusued?"
 
"If the piston surface has bee

"If the piston surface has been polished 'shiny', change it as it will not hold the oil film. Looking at a cut-through piston in a microscope it looks almost like a saw-blade. I would recommend to de-glaze all cylinders and install new rings. This for the same reason as the polished pistons."
 
piston still has "cut thro

piston still has "cut through". there is scoring on the piston near the exhaust port. i guess from over heating? some of the piston material is left on the block. can i clean the block and hone it? can the piston with scuffing be reused? thanks
 
"When I rebuilt my 1979 235, t

"When I rebuilt my 1979 235, the mechanic told me that I had something called "high ring pistons." OMC's original pistons were supposedly plagued with ring failure due to the fact that the piston was designed with the top ring too close to the top of the piston. He suggested a new set of Wiseco pistons. You could clearly see the difference. Really runs great."
 
"The reason for haveing the ri

"The reason for haveing the ring as close to the piston top as possible is to have the exhaust port opened as 'late' as possible to reduce the risk of burning off the piston edge when the port is opened. If You alter the distance from the center of the piston pin to the upper ring, you alter the timing of the port shortening the time to compleete the combustion. If You just add material on top of the piston, you encrease the compression rate. I have nothing against the Wiseco pistons, they are qute competitive in price, but I do not 'buy' the technical reason to use them. I would not mix different piston designs in the same engine."
 
"I picked up a complete 72 85h

"I picked up a complete 72 85hp motor for parts about a year ogo,it had a hot siezure on 2 cylinders but still turned over and just barely ran,but after finding that none of the parts on it would fit my other motor I decided to reassemble it. i emeryed the horrible pistons unsiezed the rings ,gave the block a really good hone and clean up. after i put it together ,old rings and all ,and run it in it came up sweet as .that was a year ago and it still gets heaps of use and goes well.
i would never do it for a customers engine but if your a skilled tightass like me it was an interesting exercise"
 
"if the piston has good compre

"if the piston has good compression to begin with , can i remove the pistons and reinstall them without chaging the ring or honing the cylinder? reason is that machine shop want a bare block to rebore 1 hole."
 
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