1970 Z/28 Pistons-Replacements?

Rosster

Veteran Member
Gold Member
Mar 1, 2020
1,106
LF2304 speed pro. Quality forged pistons with original dome shape. They are an upgraded design with low friction coating on the skirts
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G72Zed

Veteran Member
Sep 8, 2015
4,411
Canada
LF2304 speed pro. Quality forged pistons with original dome shape. They are an upgraded design with low friction coating on the skir

No wonder they only made 360/370 HP with those pistons @ 11:1 cr on high test.....yuck...looks like a 366 piston out of a School Bus LOL, enough room for another ring as well.
 

tom3

Veteran Member
Aug 1, 1999
15,157
ohio
Have to remember the OE stuff had to last - at least - through the warranty period, and at a price point. The real race stuff has no requirement except to make a lot of power. Those old tractor pistons did the job, and still are 50 years later in some cases.
 

Chevyforever

Veteran Member
Jan 4, 2011
1,555
Canada
Enjoying this discussion immensely. I can appreciate the OE style of piston, not everyone wants the thin ring set up. (most of which are flat top or larger dome hi-compression offerings). Wishing I had not sold my new 355 ci with the TRW 11-1 L2304 .030 pistons, Crane Saturday night special solid lifter cam and Dart II heads 30 or so years ago. Priced right, last forever and take a beating ...TRW POWERFORGED PISTONS ! s-l500.jpg
 

Rosster

Veteran Member
Gold Member
Mar 1, 2020
1,106
Have to remember the OE stuff had to last - at least - through the warranty period, and at a price point. The real race stuff has no requirement except to make a lot of power. Those old tractor pistons did the job, and still are 50 years later in some cases.
Yep and the warranty in 1970 was 5yrs/50k!
 

Rosster

Veteran Member
Gold Member
Mar 1, 2020
1,106
No wonder they only made 360/370 HP with those pistons @ 11:1 cr on high test.....yuck...looks like a 366 piston out of a School Bus LOL, enough room for another ring as well.
Yeah well they’ve served me well for 30yrs thru 3 different engines with ZERO issues.
 

COPO

Veteran Member
Lifetime Gold Member
Sep 15, 1999
22,300
Ontario, Canada
My latest build I used Mahle forged flat top pistons with 2 valves reliefs. Comp is 10.2. Previous to that build I used Vanolia forged pistons which will outlast any TRW’s.
 

G72Zed

Veteran Member
Sep 8, 2015
4,411
Canada
Enjoying this discussion immensely. I can appreciate the OE style of piston, not everyone wants the thin ring set up. (most of which are flat top or larger dome hi-compression offerings). Wishing I had not sold my new 355 ci with the TRW 11-1 L2304 .030 pistons, Crane Saturday night special solid lifter cam and Dart II heads 30 or so years ago. Priced right, last forever and take a beating ...TRW POWERFORGED PISTONS !

I hear ya Chevyforever, my best pass in the early 90's was 11.1 @ 120mph, and was with TRW forged FT with milled dome, press fit, tractor 5/64 rings, stock rods, 2 bolt 327 with a cast crank!! lost my tune in Napierville one day with 150 shot, lifted the heads and sucked water....bent a few connecting rods.....but never hurt the pistons LOL.
 

Evilredcamaro

New Member
Mar 31, 2022
15
If you are not boring the cylinders check the bore dia. and the piston to cylinder wall clearance. Those old forgings were set up some loose while the newer stuff is designed to run tighter. And that stock bore is probably hogged out some from wear and tear. But I'd guess it'll get a rebore?
Bad thing is the guy I bought the block from had it bored 40 over. So I guess I'm going to 60. Main reason I bought the block was the fact that it was align bored,decked and cylinders bored and CLEAN.
 




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