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Username Post: 1970 LT1 rebuild, pistons needed?        (Topic#374778)
Posts: 417
Loc: N Dakota
Reg: 11-06-01
04-01-24 04:05 PM - Post#2868513    

I would like to do a rebuild on a 1970 LT1 engine. It will have to be bored to 0.030 to get everything cleaned up. My question is about the pistons I need to use. I am looking at SpeedPro forged L2304AF30 that has a -2.40cc dish. My plan is to keep everything stock, rods and heads, etc. I believe the SCR is 10.66 while factory is 11.0:1. I want to stay out of detonation, and the best gas I can get here is 91 octane. I believe the iron heads, 2.02 are rated at 62-64cc's depending on whether they are shrouded or unshrouded. Mine are 100% stock.
I will continue with a stock cam,
242/254 @050 with 316/336 as advertised with 116 lsa
duration at 050 is 242/254
stock 1.5:1 rocker ratio 435/455
mechanical flat tappet
Should I use this piston or look for a somewhat smaller SCR?


Valued Contributor
Posts: 3341

Loc: Lake George, NY
Reg: 11-11-15
04-01-24 05:29 PM - Post#2868518    
    In response to blue_63

On paper with a steel head, compression is too high, the somewhat aggressive cam will bleed off some low rpm compression. Another issue is quench specs. Try and figure what you have.

Posts: 417
Loc: N Dakota
Reg: 11-06-01
04-03-24 07:59 AM - Post#2868546    
    In response to Shepherd

thank you for your reply. it was my thought too that with iron heads there would be too much heat. I want to keep the iron heads but i'm sure aluminum would help keep the heat level down. I'll have to go with a lower compression piston.

Valued Contributor
Posts: 4060

Reg: 04-15-05
04-05-24 02:05 PM - Post#2868609    
    In response to blue_63

Make sure you set the quench distance properly, between .039 and .045, no matter the heads/pistons you use. Not doing so will make the engine untunable.

Super Senior Member
Posts: 6614

Loc: paradise
Reg: 09-05-03
04-07-24 12:31 PM - Post#2868678    
    In response to blue_63

use a dynamic compression ratio calculator. a cam with 107ish lsa may work better. i would shoot for .040 quench.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.

Edited by bobb on 04-07-24 12:33 PM. Reason for edit: No reason given.


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