piston id?

[Frank H.]

I have this set of 427 pistons #3888304 ,but are not listed in my 1979 gm parts book or anywhere else,if someone has the time and resources
Thanks
Frank

[Clem Z.]

Re: piston id?

L-72 pistons

[Joe L.]

Re: piston id?

Frank-----

I can find no record of a finsihed piston of GM #3888304. However, where are you getting this part number from? If it's from the inside surface of the pistons, that's the casting or forging number and not the actual part number for the finished piston. The same casting or forging number may have been used for more than one finished piston part number. Given the casting/forging number, though, I strongly suspect that you have either the L-36/L-68 piston or the L-71 piston. Finding the following information would help further identify them:

1) Is the casting number the same for all pistons or are 4 of one casting number and 4 of another? The L-36/L-68 pistons were side-specific, but I don't know if they used different casting numbers for each side;

2) Is the dome configuration of the pistons the same for all 8 or are 4 the "opposite" of the other four? Same reason, as above;

3) Is the term "TRW" found anywhere on the underside of the piston near the casting/forging number?

4) Is there an oversize stamped on the top of the pistons?

[Frank H.]

Re: piston id?

I only brought one home with me,I think they where all the same ,no other markings or TRW stamp,standard bore,they came out of a 512 block with CE and numbered pad no vin high or low,casting date L 18 68,GM main std bearings and a couple 0.001 rod and standard bearing,about .0085 piston clearance,shes loose for sure.........boy you guys are fast

[Joe L.]

Re: piston id?

Frank-----

Clem's likely got it. Plus, based on your further description, that confirms it all the more. The piston clearance would be characteristic of the SHP 427 (L-72 or L-71). It's a lot more than the original factory specs, but forged pistons have a high wear rate and that's how it likely got where it is. I wouldn't expect that much clearance, even after a lot of miles, in an engine with cast pistons, like the L-36/L-68. Also, not all GM forged pistons had the "TRW" markings on the inside.

If they are, indeed, the SHP pistons and of standard bore size, then the finished piston part number for them would be GM #3888342.

[Frank H.]

Re: piston id?

I agree, after you pointed out I had the casting number, I see only two 3888 part numbered pistons, after ruling out left and right castings,just leaves the s/hp #3888342
Thanks guys
Frank

[Joe L.]

Re: piston id?

Frank------

Those are the only two GM #3888xxx numbers in the CORVETTE P&A Catalog. However, there could be (and are) other numbers in other P&A Catalogs. No matter, though, I've checked all possibilites and can tell you, for sure, that the numbers that you found on the piston bottoms were NEVER a finished part number for a piston. Also, there are no other 3888xxx piston part numbers that would "fit" these pistons.