Piston ? - Pontiac GTO Forum
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post #1 of 3 (permalink) Old 01-28-2013, 08:53 PM Thread Starter
 
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Piston ?

I have a 1970 400 and i was looking at my pistons and the number 227P is stamped on top but nothing else. I was wondering if anyone could tell me what this number is and if it is oversized. I am sure that if it is oversized that number is also stamped on the top, but i can find no part number or manufacture info to match this number. Trying to get an idea on how long these have been in the engine. Just curious and looking for some help to ease my mind.
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post #2 of 3 (permalink) Old 01-29-2013, 09:14 AM
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If they're TRW pistons, that number is telling you that they're forged. (TRW's that begin with '2' are forged, '3' is cast). If you're positive there's nothing else stamped into the tops then they're probably standard bore size.

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post #3 of 3 (permalink) Old 01-29-2013, 03:00 PM
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You can also measure the cylinder bore and determine if it's still standard or not. I agree with Bear...I have yet to see production oversized pistons that weren't marked on the tops.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring
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