oledave60

I'm tearing down the non-original engine in my 75 mostly just to get a better understanding of what it is. It's stamped CE (crate engine), casting no. is 14010207 (80-85 4 bolt truck) and the heads are 333882(70-80, 76cc). It's got good compression and very clean on inside. Now I am trying to determine if the pistons are stock or something else. It's stamped 1801 std on top and on the inside there is TRW. Is this a stock replacement? Thanks, Dave.



Also, the dome of the piston is on the bottom under the valves and the indention is on top. Are they in correctly? I've rebuilt several engines, but first time with this type piston.

Mark Riles

GM used TRW pistons in a few engines. If I recall the 1967, 1968, and 1969 Z-28 302, and in the 1970 and 1971 LT-1 350. Someone may be able to back that up or disprove because sometimes I can't remember if what I am remembering is even accurate.

anips

it looks like late 69-70 (Z-28) camaro LT 350 10.5:1, in 71 LT-1's were flat tops with valve reliefs with 9:1 comp. I believe, your motor wasn't born with those piston, they are in correctly

63mako

Yours look like they may be early to mid 70's over the counter stock replacement 1969-1970 L46/LT1 piston. Yours would be a regular forged piston. I think these are the replacements.
http://www.summitracing.com/parts/TRW-L2304F/?rtype=10
The part above is the modern equivelent in a low expansion forged piston. 1969-1970 L46/LT1 piston. About 11 to 1 W/ 64CC heads

anips

yep, Speed Pro is a copy of the TRW, they work in 302, 327, 350 engines because they all share a common 4" bore, the only difference between the three is the pin heights.

oledave60

Thanks for the info. It looks like my "crate" motor has been rebuilt at least once, but it looks good and I only want a decent driver so new rings,bearings and seals should be good enough for me.

427Hotrod

Way back when..it was very common to swap the factory dished pistons out for a set of the 11.0 forged dome pistons when the cars were nearly new. I did quite a few for folks who used the original large chamber heads to get at least a little compression in them.

So finding them in a CE engine wouldn't surprise me a bit. In fact the CE engine original purpose may have been a high compression replacement. I know if I had been ordering one that's what i would have selected..and so did many other folks. Even at the dealership I worked at..the parts guys were very willing to order slightly different stuff for a warranty job...especially with a slight tip involved!

JIM

63mako

Yes. Good possibility it was a GM shortblock. Might have a forged crank too.

69 Chevy

My apologies for nitpicking buy I felt the need to set the record straight.

that 302, 327, 350 share a common 4.001" bore. Except that the referred to L2304F piston will only fit a 5.7L/350 because of the pin height, because of its 3.48" stroke. I believe the compression distance is 1.561" for a 350 piston.

Installing this piston in a 3" stroke 302 would push the deck of the piston out of the block by ~1/2"...1/4" on a 327.

anips

no apologies needed, the 302 has a pin height of 1.800, the 327 is 1.675, and the 350 is 1.560, the compression height is the dimension from the center of the pin bore to the flat-quench portion of the piston not the top of the dome, so where did I go wrong?

63mako

Actually the piston would be right about .025 in the hole in a 350, .130 in the hole in a 327 and .255 in the hole in a 302 assuming stock 9.025 block deck and 5.7 rods

69 Chevy

You are, of course, correct Kevin. Math was never my strong suit.

I thought it confusing...and my confusion in the above post personifies that...when you made mention of this piston fitting 302, 327 and 350 size engines. I just wanted to point out that picking a piston by bore diameter alone isn't enough. The wrist pin location which is determined by the crankshaft stroke also needs to be considered.

Perhaps my remarks have muddied the waters even more? I should have kept my thoughts to myself.

63mako

Compression height is the difference. Has to match the stroke.