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GMC 302 into 50 Chev truck
#1366190 Wed Jun 24 2020 05:22 AM
Joined: Sep 2019
Posts: 17
G
GasHog Offline OP
New Guy
I am hoping someone knows what I am getting myself into. I have a 49 Canadian GMC body that will be going on a Chev frame. The Canadian GMCs used Chev engines, which means the front crossmember is the same as a Chev. I want to install a 302 GMC engine which means I will need an American GMC front crossmember. This will be moving the radiator forward the inch and a half to accept the longer GMC engine. What issues will this swap be creating when I go to install the Canadian GMC front sheet metal with the rad in it's new position? Is there a difference in front sheet metal between the Canadian and American GMCs? I am hoping someone out there has been down this road before and has some advice.

Re: GMC 302 into 50 Chev truck
GasHog #1366234 Wed Jun 24 2020 02:41 PM
Joined: Nov 2005
Posts: 5,679
3
3B Offline
Master Gabster
Hy GasHog. welcome, what size of truck are we asking about? The largest Canadian Chevrolet trucks, the 17 series (Maple Leaf 3ton) were GMC powered. I am sure there were hundreds of GMC engines swapped into both Chevrolet trucks and cars back in the day. As my experience is with Canadian trucks I have no personal knowledge of the differences in sheet metal between the Canadian and American trucks, I assume there are differences to accommodate the longer GMC engine. Good luck with your project.

Re: GMC 302 into 50 Chev truck
GasHog #1366247 Wed Jun 24 2020 04:02 PM
Joined: Sep 2019
Posts: 17
G
GasHog Offline OP
New Guy
Hello Gabster. Good to know someone is listening. The Chev frame that I am using is a 1950, 162 inch wheelbase with 750-20 tires. Doesnt say on the paperwork anything beyond that except serial number. It is an American truck, I picked it up in Oroville WA because it had a perfect pristine frame just the right length as I wanted a 12 foot flatdeck. Perhaps I should have waited to find a GMC, but I wanted to get started putting it together. I have the 302 sitting in the frame, bolted in at the back but the front mount just sitting on a block of wood to let me install transmissions and rear suspension. Its getting a Clark 5 spd and Spicer 5531 from a 53 tandem big truck. I like lots of gears. If the 302 install presents too many issues, may have to go with the 261 that is in my Canadian GMC for now, but would like to see the big 302 under the hood just for the wow factor. I am in Keremeos just south of Penticton, where are located?

Re: GMC 302 into 50 Chev truck
GasHog #1366273 Wed Jun 24 2020 07:08 PM
Joined: Nov 2005
Posts: 5,679
3
3B Offline
Master Gabster
Hy GasHog, I am in Rosedale, between Chilliwack and Hope. If you're ever in my neighborhood stop by for a tour of my rust exhibit, it takes a couple of hours.

Re: GMC 302 into 50 Chev truck
GasHog #1366430 Thu Jun 25 2020 06:14 PM
Joined: Sep 2019
Posts: 17
G
GasHog Offline OP
New Guy
Want to make a trip to the Old Car Center one of these days for parts and would love to stop by for a tour. Hopefully in a week or two. Whats your number and we will let you know when we are coming.

Re: GMC 302 into 50 Chev truck
GasHog #1366507 Fri Jun 26 2020 10:09 AM
Joined: Nov 1995
Posts: 4,556
J
Unrepentant VW Lover
Gashog -- I'm a little surprised our GMC experts haven't pounced on this one yet. But you are in excellent hands with 3B. Man, I wish I could go tour his rust exhibit. Bring a notebook as you will be learning a lot from him dance

From what I have read and seen around here, it is not terribly difficult to put a 302 into a Chevy AD truck. I have never done it and have no first hand experience with it, so hopefully one of the guys who have can pop in and walk you through it. I think it is a good upgrade and around here, the hardest part is finding the 302 in the first place.

Clark 5-speed (non-overdrive, I presume ...?) and the auxbox ... with a 261 ... hmmm, good thing you like shifting It will certainly keep you ... entertained. wave

Have fun visiting 3B!

John


John
"There is a life about to start
When tomorrow comes..."


'49 Chevrolet 3804

Re: GMC 302 into 50 Chev truck
GasHog #1366527 Fri Jun 26 2020 02:29 PM
Joined: Jun 2011
Posts: 3,512
E
Shop Shark
Gashog, with the correct diff. ratio, the 5-speed alone should certainly be adequate without the Brownie, unless you are up for the extra work. A 3.55 or thereabouts ratio should work well, unless you have very large tires, then 4.10 ratio would work.

Ed


'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
Re: GMC 302 into 50 Chev truck
GasHog #1366593 Sat Jun 27 2020 12:11 AM
Joined: Nov 2000
Posts: 1,909
F
Shop Shark
Ed, he wrote that he has 162” wheel base, 7.50-20 tires and wants a 12’ flatbed. I would guess it will have a 6.17 ratio.


Professional Novice
Re: GMC 302 into 50 Chev truck
GasHog #1366626 Sat Jun 27 2020 06:03 AM
Joined: May 2006
Posts: 838
T
Shop Shark
Hi.i can’t answer your questions about Canadian GMC versus American GMC sheetmetal differences. I would venture a guess there is not a significant difference between the fenders, hood, lower apron, and bumper pan (assuming Canadian GMC’s used GMC sheetmetal and not Chevy front clips) (same manufacturing process using same stamping machines).

It would be best however, that your change to a GMC front crossmember would also include the GMC radiator core support, hood latch assembly, radiator cover, and upper cross brace to be consistent with mounting the GMC radiator and front clip reassembly. Consider the GMC lower radiator hose as well. All of these are found through vendors, EBay, and sources here by posting in the Truck Parts Wanted forum.

Dropping in a 302 is no harder than any other Stovebolt engine swap or upgrade.

I hope this helps... I am not an expert by any means, but this reply should get you started in the right direction, and perhaps prompt a more seasoned veteran here to chime in and either find merit in this posting or not. -Tom

Last edited by tom moore; Sat Jun 27 2020 10:14 AM.
Re: GMC 302 into 50 Chev truck
GasHog #1366759 Sun Jun 28 2020 01:38 AM
Joined: Nov 2005
Posts: 5,679
3
3B Offline
Master Gabster
Hy GasHog, I sent you my contact information in a PM


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