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 Blocks / Cranks/ Rods and Pistons
 chamfer the bottom of cylinder wall
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Miles
Cochise

Canada
209 Posts

Posted - 24 Dec 2017 :  12:51:15 PM  Show Profile  Reply with Quote
After re-bore the bottom of the cylinders are quite sharp. Is it common to relieve the bottom of the cylinders to prevent the piston from being scraped by the bottom of the cylinder? Have 6 thou clearance but piston can still tip slightly at BDC

Blued and Painted
Chief PONTIAC

USA
3505 Posts

Posted - 26 Dec 2017 :  10:43:21 AM  Show Profile  Reply with Quote
I don't recall seeing it done? A 1/32 radius Or de-burr could be preformed. But some fine metal dust could get into hidden arias if not throughly cleaned again.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Miles
Cochise

Canada
209 Posts

Posted - 26 Dec 2017 :  8:15:36 PM  Show Profile  Reply with Quote
I searched quite a bit and found a machinist site. They say they smooth the bottom of the bores off to reduce the risk of the sharp edge scuffing the piston. Say it has to be as smooth as a baby's A..
they us a small disc of some sort and then fine paper to smooth the sharp edge. Makes sense the bottom of the piston goes below the bottom of the cylinder at BDC if the piston tips/rocks even slightly it could catch the sharp edge.
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