A question concerning forged pistons: I'm in the process of rebuilding my 327 and I noticed that upon removing the forged pistons today I could see very fine score lines on the pistons and in their respective cylinder bores. These score marks coincided with the piston skirt. What I'm wondering if is this is conducive to using forged pistons .. ? .. If so, could this be considered normal operation .. ? .. The score lines appear to be very superficial and hard to 'feel', even with the fingernail test. The cylinder bores, in the piston skirt area, appear to be slightly burnished too. I would like to reuse these pistons, if possible. Is there a problem .. ?.. I was wondering what you guys think ..
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Re: forged pistons
John,
The very fine lines you are seeing are normal in an engine with miles on it. Check out the skirts for oil grooves and dimensional size. If a little honing is all you need and are still in size limits reuse is OK. Not good but OK. Be sure to use new rings. Never knurl pistons for reuse. The other thing is used pistons have ring land wear that is not as detectable. For the small cost of SB TRW pistons I would replace them for my own standards. -
Re: forged pistons
John,
Gene is correct in his answer as the pistons skirts will slap the walls of the cylinder.
The cost of TRW forged pistons is pretty high these days but you can find several piston manufactuers that are reasonable. If you do decide to use new pistons, I would go oversize 0.030 and insure that the rebuild job was perfect.
Good luck with you rebuild,
JRComment
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Re: forged pistons
If your car is to be a street car and not an all out racer, you may want to consider hypereutectic pistons if available. They're very strong, dirt cheap compared to forged, and fit with a very tight piston to wall clearance for less noise upon cold startup and longer ring life. If you still have money left, consider springing for the gapless piston rings - only 2% blowby - so your oil doesn't get as full of gunk, especially for cars that are infrequently driven.Comment
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Re: forged pistons
The engine was bored .030 over and TRW forged flat top pistons were installed, circa 1974. I figure this set of pistons have about 20,000 miles on them (non working odometer) and appear to be in good servicable shape. A little piston slap noise is ok since I will be using a solid lifter cam this time around, so whatever sound should just 'blend right in' .. If hypereutectic pistons are available I might consider going that route too, though it appears I would need to go to the next overbore size, .040 over, to gain the proper piston-to-wall clearance .. Thanks guys for the replies and suggestions ..Comment
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