replacement engine questions

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Jan 12, 2006 | 11:58 PM

ferndog4

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Instructor

Joined: Dec 2003

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From: ca

replacement engine questions

Group,

Take a look at these pictures. This is a replacement engine ive been looking at. Can anyone tell me what Compression thse pistons might be? I cannot locate much info via google. The number on them say 3959456 and I will be running a 64CC Iron head on the street. The block is a four bolt #14016379. Said to have a forged crank #1182 and pink rods? It is still standard bore. Please let me know what you think.

fm

Jan 13, 2006 | 02:19 AM

Shirley1978

Burning Brakes

Joined: Jan 2006

Posts: 761

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From: san jose California

is it a goodwrench engine?? me and my dad swaped the stock engine on my 78 awhile back and put in a goodwrench 350 replacement engine good for about 220 hp out of the box... the compression was like 9.0-1 i think.. but im not sure..

Jan 13, 2006 | 02:23 AM

Kalway

Safety Car

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From: San Diego CA

If it's a truck engine the compression is usually like 9 or 9.1:1.

Jan 13, 2006 | 03:45 AM

Solid LT1

Le Mans Master

Joined: Dec 2003

Posts: 5,727

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From: Fremont CA

Pistons are 1970 LT-1 11:1 compression with 68cc heads. A little too high for pump gas unless you go to 72cc Chamber aluminum heads on the motor. DO NOT run with early small chamber heads unless you want to run 25-30% 100octane or better race fuel mix. Block casting number isn't one I am familiar with but, I do know those pistons, they are 1970 model year LT-1 pistons.

Jan 13, 2006 | 10:04 AM

ferndog4

Thread Starter

Instructor

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From: ca

70lt-1

11:1 is a bit high. i will be using Dart 64CC Iron Eagle Heads. In order to change this what must i do. Can I keep the crank but change the pistons? Would their be a balance issue? Or should I buy a new rotating assembly kit? I would like a nice sturdy bottom end.

thanks!

Jan 13, 2006 | 12:45 PM

ltlevil

Burning Brakes

Joined: Apr 2004

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From: Des Allemands LA

Block is 77-79 350 2 or 4 bolt main. Can't seem to find casting number for the heads.

ltlevil

Jan 13, 2006 | 01:19 PM

GOSFAST

Burning Brakes

Joined: Feb 2005

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Quote:

Originally Posted by ferndog4

If those pistons are original LT-1's you can substitute a set of L-82's probably without rebalancing. Depends on piston brand. The L2304's (LT-1's) weigh 580 grams and the L2417's (L-82's) weigh the same. TRW was the G.M. OEM supplier for the original forged pistons. Hard to tell from photo if they are forged or cast. There was cast available also, but not factory issue. Thanks, Gary in N.Y.
P.S. I do know the L2417F's in +.030's have been discontinued. I'm not sure about the other sizes.

Jan 14, 2006 | 12:31 PM

cardo0

Le Mans Master

Joined: Oct 2002

Posts: 7,098

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From: Las Vegas - Just stop perpetuating myths please.

Save urself some headaches and stay away from that thing.

U couldn't give me that thing unless i needed the scrap metal - and i don't have room even for that.
But really that should be a 2 bolt '77-'79 block (can't verify 4 bolts in pix) so those are used early pistons installed in a late block.

If u can't afford a GM Goodwrench LM1 or rebuild ur own from scratch, try an Ecology or Pick Ur Parts boneyard and search for a low mi used block with guarentee to run for $200. U will have to pull the eng urself of course but they allow u to run it before purchase too. And there are plenty of Chevy 350's waiting in the yard - some 400"s too if u dare to look enough.