The Stovebolt Site Forums The Shop Area Engine Shop 248 GMC???

A year ago last January I attended a farm/junk sale that had several old trucks (1 1/2 ton+) on the bill. By the time I arrived the trucks I was interested in had sold and I was unable to find out who bought them. There was a 51(?) GMC 1 1/2 ton I was interested in because it had good tires and I need some good tires for my 42. I hung around thinking I would find the new owner of these trucks and maybe get a bargain. The auctioneer announced that everyone had 30 days to get their junk hauled off.

Today I went to this same farmstead under different ownership to work on a tractor and the trucks that I was interested in were still there. I asked the farmer who owned all that stuff down there and he said he did. Ah ha!! Things were looking up, for a change. He had hired some guy to haul off all that stuff but the contractor was not making much progress--too much snow in the winter and too many rattlesnakes in the summer.

Anyway, for $50 I am the proud owner of a GMC 350 truck serial number 35324P4897. The engine number stamped on the boss next to the distributor is 248132804. I am not familiar with GMCs but I kind of remember the first digits of the engine number are the displacement. Is this correct? I now have 3 almost new 8.25X20 tires and have my eyes on another matching tire on another truck that I may be able to get without getting the whole truck. The engine turns over and is not covered with grease. The truck has 55K showing on the speedo and has a box and hoist. The truck is equipped with a vacuum operated 2 speed rear axle (Eaton, I think).

If this engine is any good I think I will put it in my 51 Chevy half ton pickup, after making the necessary adjustments for the additional length of the GMC engine.

If Mr. Proffitt or any other resident GMC experts would be kind enough to tell me exactly what I have and any concerns/benefits on the 248 I would appreciate it greatly. Just what I need--another project :p I only have 4-10 more tractors to mechanically restore :rolleyes: Just need more.....

You are correct. The first three digits of the engine number on the GMC's are the engine size. It is a 248.

35 3 24 P 4897
35 = 350 series truck
3 = 161" wheelbase
24 = 248.5 cubic inch engine
P = Pontiac, MI assembly (not Oakland CA)
4897 = Your truck was the 3897th of the 16,363 350 series GMCs built on the Pontiac, MI line in 1951.
GMC 350 Series Serial Numbers

With respect to your question about what do you have...You have a full pressure GMC 248 truck engine as opposed to the original 216 low pressure Chevy engine in your 3100.

The debate between these engines' individual advantages will go on, but in my opinion it's a good reliable truck engine and certainly cranks out more Hp and torque than the corresponding 216 babbit pounder...that of course is assuming that you still have the stock motor in the '51 Chevy 1/2 ton.

Parts are fairly available for both the truck and the engine for the most part. Congratulations!

"You got a Real Truck...You got a GMC"

Bastardizing neat trucks for the "tires"? :mad: I have a 52 tractor cab and it needs plenty of body/cab stuff. Mostly dash items as windows are out and dash is all rusty and PO has a zillion odd "controls" added/changed cause of the Diesel in it. If you buy anymore and want to "part" any cab stuff let me know. You'll see that the old GMC's were built heavier and tougher than the Chevs, even tho they look the same mostly. Better engines too.

Racecarl, I have been beating on a 248 jimmy since July, '97. I have nothing but respect for it. I recieved it with 69k, now it has over 72k miles on the odo.........2 speed, vacuum shift EATON axle (model 1350). 8.10 in low and 6.13 in high. Not bad as long as you run the 8 and a quarter 20's......... Dump the Zenith carb, I have a Rochester "B" from a 235, works fine. 9 MPG, empty or loaded. Never overheats and has power assist brakes.
A good work truck, it has never left me anywhere. I have a line on a low mileage 270 if the 248 blows up.............

Thanks all for the info. I did a little research on an old Motors Manual and found that the bore on a 248 is 3.71875 and stroke is 3.8125.

A 235 Chevy has a bore of 3.5625 and a stroke of 3.937. I am running a 235 in my pickup, but it is not healthy. I think the shorter stroke and bigger bore would work better for my pickup. Plus I just knew GL would need some GMC parts. When I get the truck out of it's current graveyard and remove the packrat nest, I will take some pictures for any and all interested parties.