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#1
08-25-2008, 06:05 PM
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L:88 piston ID
Anyone know the TRW/GM part# that should be stamped on the top of a L88 Piston?
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'70 L78 NOVA SS '77 Bronco 
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#2
08-25-2008, 06:27 PM
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Re: L:88 piston ID
It looks like the Std. bore TRW/GM 1969 L-88 piston was #3959105,to be used with the "New" #074 Al. head w/118.0 cc.
GM #3959106 was .001 oversized. GM #3981891 was .005 oversized. GM #3959107 was .030 oversized. They list another one,which I think was specific to the 1968 Corvette L-88 which used the #842 Al. Head. w/106.8 cc. They are: GM #3909857 was Std. Bore. GM #3909858 was .001 oversized. GM #3909859 was .030 oversized. GM #3909860 was .060 oversized. Sometimes the last 4 digits are pressed in them.
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#3
08-25-2008, 08:45 PM
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Re: L:88 piston ID
Thanks for the info.. I am trying to determine if my car has the L-88 pistons in it without pulling the engine. I have scoped the pistons and they appear to be the big dome ones and have a number (hard to read)stamped into the top of each piston but those numbers you gave me do not match what I THINK I see. The car has open chamber 990 heads on it and a pretty radical cam so I think they are L-88 style.
__________________
'70 L78 NOVA SS '77 Bronco
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#4
08-25-2008, 09:15 PM
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Re: L:88 piston ID
perhaps they are LS-7 pistons...those are dome pistons similar to the L-88s, except for the LS-7 454 engine which also used 990 heads, it got a healthy cam too...just a thought
__________________
I don't think it was coincidence that the Great Depression happened during Prohibition... 
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#6
08-26-2008, 12:53 AM
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Re: L:88 piston ID
Left it at home so will post later. I do know that the pistons do not have an over bore size stamped on top so assume it is a std. bore.
__________________
'70 L78 NOVA SS '77 Bronco
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#7
08-27-2008, 04:11 PM
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Re: L:88 piston ID
Here is what I THINK is stamped on top of the pistons:
L2808A. I am unable to get a clear shot at the stampings due to my scope not having an optical extension with a "memory". I can not bend the optic cable in a stationary position in order to get a good view of the lower top side of the piston where the stamp is.
__________________
'70 L78 NOVA SS '77 Bronco
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#8
08-27-2008, 08:28 PM
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Re: L:88 piston ID
That is a TRW number. If you call them and get the right guy they will sometimes go into the archive and tell you what it is.
Jason
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#9
08-27-2008, 08:49 PM
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Re: L:88 piston ID
It's probably an L2308 which is correct for an L88 427. Now it might also have another stamping showing the oversize, like .030 or .060
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Rick 69 Chevelle SS396 Silver L78 M21 Post Sedan (Berger Chev.) 69 Chevelle SS396 Black L78 4-speed 4.10 Post Sedan  Don't text and drive. Somebody's life may depend on it!
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#10
08-27-2008, 09:42 PM
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Re: L:88 piston ID
I went to their web site and pulled up some info. but no number like this. Will give them a call. Thanks.
__________________
'70 L78 NOVA SS '77 Bronco
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