C1500 v6 to v8 help

Kendricktuuufhkh · Apr 27, 2021

Hey Wanted to know if anyone has experienced swapping a C1500 v6 to v8 . I removed my 4.3 tbi engine and replaced it with an 454 from an c10 body (86) , but I can’t get the motor lined up in the engine mounts . I wanted to know if the chassis is the same on a V8 and or does the 87 clam shells differ

Nickpisp · May 3, 2021

You need V8 motor mounts on the frame.

Schurkey · May 3, 2021

Kendricktuuufhkh said:
I removed my 4.3 tbi engine

From WHAT MODEL-YEAR VEHICLE?

Kendricktuuufhkh said:
and replaced it with an 454 from an c10 body (86) , but I can’t get the motor lined up in the engine mounts . I wanted to know if the chassis is the same on a V8 and or does the 87 clam shells differ

I'd have guessed the brackets on the engine were different from what's used on a GMT400, not the mounts on the frame.

But I've never done that swap, and I don't know what vehicle you're doing this on.

sewlow · May 3, 2021

GMT400 V6 frame side engine mounts are different from the SBC/BBC ones.
SBC & BBC frame mounts are the same.
V6 mounts are further back on the frame than the V8's.

Moving the V6 mounts to the V8 position doesn't work.
Because of he shape of the frame, the V6's mounts in the V8 position, & the actual mount points end up at the wrong angles.
Swapping them side-to-side doesn't work either.

The O/P needs V8 frame side mounts in the proper V8 position on the frame.

Schurkey · May 3, 2021

^^^ Yup. Absolutely correct. I looked up engine mounts for my '88, as a V-6 and as a V-8. Different part numbers. No promises on the engine brackets interchanging from Squarebody to GMT400. Maybe yes...maybe no.

I got into trouble with them on a Trans Am/Pontiac 455 project. Found out the F-body engine brackets were different from the "big car, B-body" engine brackets.

Cheap-junk Anchor-brand rubber cushions/frame mounts:
For V-6
https://www.summitracing.com/parts/ani-2436/make/chevrolet/model/k1500/year/1988

For V-8
https://www.summitracing.com/parts/ani-2637/make/chevrolet/model/k1500/year/1988

The #2637 "V-8" mounts are total garbage.
http://hbassociates.us/K1500_Engine_Mounts_03.jpg

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PlayingWithTBI · May 3, 2021

IIRC, on Hot Rod garage they took a tube of polyurethane window sealant and filled the voids between the rubber cushion and the sheet metal on their motor mounts, said that firmed up the support of the engine.

Schurkey · May 3, 2021

Hmmmmm. I should think about that.

After looking at the **** sold by the aftermarket, I put my 300,000-mile original rubber mounts back in when I installed the engine.

So far as I can tell, I'm not having any problems due to the worn-out OEM mounts.

Erik the Awful · May 4, 2021

Schurkey said:
After looking at the **** sold by the aftermarket, I put my 300,000-mile original rubber mounts back in when I installed the engine.

So far as I can tell, I'm not having any problems due to the worn-out OEM mounts.

So, you got 300,000+ miles out of the factory mounts, and you're upset the aftermarket went cheaper? While they do look flimsier, I wouldn't have a problem running them. How many times have we heard of them breaking? Truly asking here, because I haven't heard of it.

stutaeng · May 4, 2021

I changed the center support on my 99 Silverado 2wd and the replacement made by Anchor looked pretty cheap. The OEM had rivets holding the metal parts and the Anchor had tack welds that were touched up with paint, but they didn't really bother removing the weld bbs.... The original had pressed studs and the anchor had regular hex bolts. All for a whopping almost $100 at the local parts store. I hope it lives long!

stutaeng · May 4, 2021

Here you can spot the differences:

Tag said "Hecho en Thailand."

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C1500 v6 to v8 help

Kendricktuuufhkh

Newbie

Nickpisp

OBS Enthusiast

Schurkey

Supporting Member

sewlow

Bitchin' Stitchin'

Schurkey

Supporting Member

PlayingWithTBI

2022 Truck of the Year

Schurkey

Supporting Member

Erik the Awful

Supporting Member

stutaeng

I'm Awesome

stutaeng

I'm Awesome

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