The Stovebolt Site Forums The Shop Area Engine Shop GMC engine vs. Chevy

I was surfing around looking at various posts and saw a comment that the old GMC engines were better than the Chevy engines. Can someone pls. enlighten this newbie on this?

Thanks

GMC used Pontiac engines

When GMC introduced their own OHV 6-cylinder engine in (1939?) it had insert type rod bearings with oil pressure to the rods, while Chevy still had the babbitted rods and the dipper/ nozzle/ trough oiling of the rods. Some say everything about the GMC engines were built more heavy duty. They were “truck” engines.

What years and what engines?

Pontiac engines were available in GMC trucks from 1955 onwards (New Design GMC trucks)

older GMC engines (1955 Z-series and earlier) GMC trucks:
The GMC 228, 248, 279, 302 (6-cylinder engines, referred-to by Frasnk50, above) were not Pontiac engines.

Pontiac engines were available in GMC trucks from 1955 onwards (New Design GMC trucks)

older GMC engines (1955 Z-series and earlier) GMC trucks:
GMC 228, 248, 279, 302 (6-cylinder engines) were not Pontiac engines.
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And to add to that: in 1960 the standard engine in the pickups was the GMC 305 V6, this was not a pontiac engine, and believe from 1960 and up never another pontiac engine came down the line in a GMC, although later they offered chevrolet engines in GMCs

And don't forget about the Buick Nailhead engines in some of the GMC big trucks from '57-'59.

I believe the assertion of "better" is from the pressurized oiling in earlier GMC's as Frank stated.

That would be “higher pressure” oil system in earlier GMC 6 cylinder engines?

Even low-pressure Chevrolet engines had/have pressurized oil lubrication systems.

I think I have heard/read that the GMC blocks and heads were harder (more zinc, maybe).
If so, they were harder metal.

It is late, and I have had a few wee drams. Forgive me.

GMC sixes were designed to be rebuilt multiple times. The pickup and midsize truck engines benefited from the same design features as the big rig engines- - - - -some of those engines even had cylinder assemblies that were separate from the crankcase, such as the 503 cubic inch inline six used in the mid-1950's heavy duty trucks. For instance, GMV 228-302 connecting rods have full-floating wrist pin bushings and lock rings in the pistons to retain the pins- - - -Chevy uses a clamp bolt in the rod to lock the pin to the rod. GMC oil pumps are huge compared to Chevy pumps, and the GMC runs approximately twice as much oil pressure. GMC has a much better cylinder head design- - - - -and the list goes on and on!
Jerry

Carl, Chevrolet used the Buick Nailhead (while they developed the 348), not GMC...

Mike B

In the early 1930's GMC used Pontiac and Buick engines im their smaller trucks and Knight sleeve-valve engines in the bigger rigs. A few of their off-road rigs used for mining and dam construction projects had engines that displaced 700+ cubic inches. Pontiac and Oldsmobile V8's were used in some applications in the mid-1950's.
Jerry

GMC big trucks even had Olds 370 engines in '50's trucks.

Ed

GMC has an interesting history as it started outside of GM. By the 30s they used engines from other GM divisions including Oldsmobile and Pontiac.
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