DarthD

The original pistons from my 1985 had a single wedge valve relief and were cast 336744 262-99 TRW.

I acquired an engine from a 1986 Vette that has different pistons. They have 4 valve reliefs and are cast 14088801 E6290 GM.

Are the pistons from the '86 Corvette forged pistons? I do not see why GM would have used different pistons in '86.


This is nothing important, I am just curious.

AGENT 86

The 86 piston is cast

CFI-EFI

984 and 1985 pistons have the valve clearance trough as you describe and are forged. They are GM part number, 474190, in standard. The 1986 used different pistons for the cast iron and the aluminum heads, both were cast pistons. The aluminum headed pistons are, 14093695, standard, and the pistons for the iron heads are 14101185, standard. 1987 and '88 cars used a different part number and 1989s were different still, although, all cast.

RACE ON!!!

Midnight 85

The pistons in my 85 have the 4 "eyebrow" valve reliefs, not a single trough design. As far as I know my engine is the original but now I wonder. Since it is coming out in a few weeks I will check to see if the pistons are forged and I'll also check the numbers on the block.
CFI, I don't doubt your word at all so maybe they changed piston design later in the model year?

CFI-EFI

I'll bet a nickel against a donut, that yours are not the factory pistons.

RACE ON!!!

DarthD

Thanks.
I thought all Corvette L98 pistons were forged. Are they all cast from 1986 - 1991?

AGENT 86

I believe so