The Stovebolt Site Forums The Shop Area Engine Shop G M C in my 53 ?

Hello Everybody,
It's been a while since my last post, life keeps putting my AD on the back burner,anyhow I have a question on a 55 second series G M C 6 cylender. Friend is pulling it out to make room for a v8,he says it is a very good runner.I don't know the cid and haven't seen it but he says it is a GMC not a Chevy, so I was wondering what kind of girations it would take to put it in a 53'1/2 ton AD? Thanks for the input, Aaron

I believe GMC's are longer than the Chevy inline 6, so you may have to move the radiator forward.

If it is a 55 gmc, it will either be a 248, or 270. If you are real lucky someone may have put a 302 in there. Behind the distributer there is a flat spot with a number stamped on it. The first 3 numbers give you the displacement.

There is much to read about swapping a gmc 6 in where a chevy 6 used to be. It always involves moving the radiator forward as the GMC engine is longer. You may have to drop the oil pan and timing cover on both engines and swap the front timing plate. The 55 second series used a funky horse shoe type of motor mount that bolted to the side of the engine. Use your original bellhousing and clutch linkage from your 53. You can put the larger 11 inch clutch setup on the gmc flywheel... an upgrade from the 9 1/8 clutch on the chevy.

John

Thanks Guys,
How about the short shaft water pump? I dont see one listed for the GMC will Chevy work or are the GMC motors totally different from the Chevs? Also what about the stock temp gage sensor? By the way the 53 is a chevy.

Temp gauge sensor will work but you'll need a GMC oil pressure gauge. Your 0-30 gauge will peg out.

It will be worth all the hassles to do it. It will take some doing but nothing worth doing ever comes easy.

Hey Thar Cletis, I have a close friend that I nick named Cletis. He wants a Cletis truck. I found a GMC about a 52 or 53 with the 270 in it. Its in the blackberry bushes at an aquaintances house in the country. Its in good shape and can get it cheap. Needs some TLC but it may run really good. Anyhow, your 6100 looks like Towmater without the Ta! Just thought I would through that in for some humour. Just have to remove the hood and let is get rusty looking like to one on the Cars movie. Can't wait to get my bolt installed hopefully within a week. Better than a V thing I believe. Henry

chevy pump won't work on a GMC. They are 2 completely different dogs.

GMC's already have about as short of a shaft water pump as you could put on there. It is similar to the 216 style but not the same pump. It mounts high, between the block and head. The block is actually longer, so you have to move the radiator to be able to mount it and keep the harmonic balancer from rubbing on the radiator.

I'm going to put a 302 in my '50. It's sitting in my garage, I need to go over it. It runs but I want to hop it up, and I need to figure out the flywheel situation. It came out of a '55 dumper with a big old Clark 5 speed and a Brown/Lipe clutch. The bellhousing is too big.

4onthefloor

I believe an 11 inch clutch setup will fit on your 302 flywheel, and in the 1950 bellhousing. I have a NAPA part number for a clutch set that should work... MU5473-1B. The pressure plate mounts to the bellhousing with 6 bolts. Unfortunately the kit does not come with the correct pilot bearing/ bushing. You will have to cross reference a New Departure 7109 bearing.

Anyway that's the clutch I will be running on my 302 with a 1940 bellhousing.

John

The flywheel I have doesn't even physically fit in a 1950 bellhousing (I tried), its a good 1.5" bigger in diameter, and it has a solenoid starter. It has heat cracks in the surface anyway. The 302 I have has the special bubbled out big truck bellhousing. I need to find a 6-bolt pickup truck bellhousing.

I have an 11 inch clutch on my 261 so I know that fits. I just need to get another flywheel.

Thanks for all the advice Guys,
The other thing I didnt mention is that I am planning on useing a T-5 and I dont know how this will work out. I do have two other power plant options one is a non running 235 looks to be a good builder and the other is 1978 250 that runs great the downsides to it are I would really like to keep my foot starter and it has the intergrated head but on the upside it is in great running condition and made to run unleaded.I think I will still get the GMC and keep researching all 3 options. I have plenty of time to make the powerplant deciesion as of my game plan on this project is to get all the body rot repaired first. Thanks again Aaron

The gmc will run plenty fine on no lead gasoline. I put over 60,000 miles on one with no lead. When you tear it down it is a good idea to put the hardened seats in.

bigbadswingdaddy, the water pump from a 216 will bolt right on a GMC engine, I have done it several times. Aricheson, see if yo can find a core support from a GMC, the radiator will be positioned right. Front motor mounts will be a bit forward of the Chevy ones, I used F**d stock length spring shackles as spacers, they are just the right length. Everything else is a bolt it.

chevman, thanks for the correction. I had no idea.

chevman32,the late 1930's 216 pumps are probably interchangable with GMC,but for sure not the pumps from after that period.I just compared a early 50's 216 pump to a 228-302 GMC pump,bolt pattern spacing is not the same.
I installed a GMC 302 in a 37 Chevy pu,other than moving the radiator foward about an inch and a half by repositioning the radiator side brackets and fabricating a front mount,it's a no brainer swap.The GMC flat stle 11 inch flwheel and diaphram clutch fits inside a AD truck bellhousing with no problems.