Vortec 5.7 Engines - Difference Between 8600+ GVWR 2500/3500 and "normal" 1500/tahoe/burb Engine?

mistaake · Jul 28, 2016

Summit has two different PN Chevrolet Performance crate engines... one for less than 8600 gvwr and one for 8600+ gvwr. what is the actual difference? are they interchangeable? i am eyeing a rclb 97 gmc c2500 with 4l80e and 3.73 gears that is in good condition but needs an engine. i want to know if i can put a used engine from tahoe/yukon/suburban/1500 truck in it?

http://sfbay.craigslist.org/scz/cto/5688036404.html

DerekTheGreat · Jul 28, 2016

Only thing I can think of would be that the higher gvwr would be a 4-bolt main block and that the half-ton stuff would be a regular two bolt.

mattillac · Jul 28, 2016

....Notes: Vehicles under 8,600 GVW.....

Description:....... long block assemblies are built up from 1996-2002 style 2-bolt main blocks......

https://m.summitracing.com/parts/nal-12530282

....Notes: This fits 3/4 and 1 ton trucks, not 1/2 ton. For 3/4 and 1 ton trucks with the heavy duty option. 8,600 and over GVW.....

Description:......L31-R long block assemblies are built up from 4-bolt main blocks....

https://m.summitracing.com/parts/nal-12530283

According to the summit description, under 8600 is 2 bolt main , 8600 and over is 4 bolt.

Christian Steffen · Jul 28, 2016

I had one out of a 1 ton and it did indeed have 4 bolt mains, but I've never had one out of a half ton apart.

mistaake · Jul 28, 2016

DerekTheGreat said:
Only thing I can think of would be that the higher gvwr would be a 4-bolt main block and that the half-ton stuff would be a regular two bolt.

I read that, and also that the heavy duty one has hardened valves? In real world if I put in any 5.7 engine it will work fine in terms of motor mounts, sensors, fuel injectors, tuning, etc?

Thank you.

Jrgunn5150 · Jul 28, 2016

mistaake said:
I read that, and also that the heavy duty one has hardened valves? In real world if I put in any 5.7 engine it will work fine in terms of motor mounts, sensors, fuel injectors, tuning, etc?

Thank you.

I'm sure it would. I have an 8600 lb truck and the only difference I'm aware of is the exhaust, and my heads have different casting numbers with different valves.

MIHELA · Aug 1, 2016

Get the 8600+ one. The only difference is 4 bolt mains.

Texcuda · Aug 1, 2016

The primary difference is 3/8" vs 11/32" valvestems. Assuming you are swapping a complete motor then you shouldn't have any problems. The heavy trucks have a larger diameter valvestem to handle the heat generated from lugging the motor while under a heavy load.

Vortec 5.7 Engines - Difference Between 8600+ GVWR 2500/3500 and "normal" 1500/tahoe/burb Engine?

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