im building a 327 the is 10 over bore.im getting ring gaps from .020 to .030.i had the machine shop check the bore and the taper.he said most was square and some .010 to .020 out.he told me to build it.please help
You're gonna have to get a 4"-5" micrometer and a dial bore gauge to check it properly. Set the mic to 4.010" and zero the bore gauge with the mic. Check each cylinder at 3 different places. If you were told it was checked and it varied from .010 to .020 he should have stopped you right there. I wouldn't even attempt to build an engine with a bore variation over .002".
Us poor guys get get away with checking piston to wall clearance by putting a piston (no rings)in the hole upside down, then seeing how big a feeler guage you can get past the skirt.
To check taper, put a ring in, use a piston to square it in the bore, and check the end gap. Do it top, middle and bottom, if the end gap changes, you have taper. The piston skirt has to be in solid for this to work. bottom and middle, you can put the piston in upside down and push the ring, to get the top, piston right side up, then the ring, then push the piston up from underneath to square the ring. If you're really good at math and pie and stuff, you can even calculate how much taper.
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