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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Mar 2003 Posts: 1,132 Shop Shark | | Shop Shark Joined: Mar 2003 Posts: 1,132 | I am curious about early GMC trucks that had pontiac engines. Were they 6s, 8s,flatheads or OHVs. What years?
Weeds | | | | | Joined: Oct 2003 Posts: 94 'Bolter | | 'Bolter Joined: Oct 2003 Posts: 94 | I have a 1928 GMC 1-ton that has a split flathead straight 6 engine. I believe the displacement is 186.5 As far as I know, this engine was only used in 1928-29. There was also a Buick OHV straight 6 engine that was used, but I'm not sure of the dates. I think it was pre-1928. | | | | | Joined: Feb 2004 Posts: 29,869 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,869 | Mid-1950's GMC's had Pontiac overhead valve V8's as an option, usually with the 4 speed Hydramatic transmission. I drove one tractor-trailer rig with that combination, so it was not just limited to pickups. Way back in the 1930's I believe some GMC's ran Oldsmobile flathead 6's.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2003 Posts: 1,132 Shop Shark | | Shop Shark Joined: Mar 2003 Posts: 1,132 | MT53 and Jerry,Thanks for the replies, Trying to find some history on these engines. My next project, assuming I live that long,is a 35 Pontiac 2 door coach. flathead 6,suicide doors, engine froze tight. I have found a 38 engine that was running and will swap that into the 35. Jerry I Was not aware that Pontiac V8s were used or Oldsmobiles either. So it seems Buick, Olds and Pontiac took turns powering Jimmys. How come? Didn't GMCs have an engine of their own?
Weeds
Last edited by cletis; 03/29/2015 9:53 PM. Reason: deleted off topic content.
| | | | | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | GMC had their own inline 6 cylinders from 1939 to 1959. Then they introduced their V6 in '60. Jerry is correct they used Olds engines until '39. | | | | | Joined: Jan 2008 Posts: 4,962 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,962 | GMC used a 324 Olds V8 in 55 and 56 and a 371 Olds in their 57 to 59 trucks. It was limited to the 550 and 650 series trucks. Chevrolet used a 322 Buick engine briefly. Actually Chevrolet came out with the first true General Motors truck engineered V8 with the 348 in 1958. My theory is that GMC was already toying around with their V6 and that is why they they didn't really develop a V8. They did come out with a 637 V8 in the early 70's, but it was already a Diesel world by then. Chevrolet dominated the gasoline powered truck market with the 348 and 409 in the 60's. GMC lost a lot of market share in the 60's because of their V6 and not offering anything but a Detroit in their larger trucks. By the time they offered a Cummins in the mid 70's, their market share was lost forever. | | | | | Joined: Feb 2004 Posts: 29,869 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,869 | The 348 was never intended to be a passenger car engine- - - -then the supercharged Ford 312's started beating the Chevy 283's on the drag strip in 57 and Chevy panicked. They worked up a 3-2 barrel intake and a solid lifter cam for the 348 truck engine that was in the final stages of testing and stuffed it into the 58 Impala. The engine had the cubes, but it suffered from valve float above 5500 RPM. The guys who were used to winding the 283's 6,000+ RPM were not impressed! Some of the 348/409's were modified into early 427's before the straight valve cover models came out.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2010 Posts: 10,303 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,303 | The '57 GMC trucks were available with the 347 Pontiac.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Mar 2003 Posts: 315 'Bolter | | 'Bolter Joined: Mar 2003 Posts: 315 | The 186.5 Pontiac was used in 1928 and was increased to 200 and used from 1929 to 1934. The Olds 213 was used from 1935 to 1936, it was increased to 230 in 1937. In 1938 GMC used the 221 Pontiac engine. In 1939 the 228 OHV engine was used. | | | | | Joined: Apr 2005 Posts: 1,971 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 1,971 | 1959 had a Pontiac 336 V8. | | |
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