I just thought I was pretty good at old motors but this one got past me. I had no idea GMC made a 478 cid V-6. 254 Hp at 3200 RPMs and 442 ft. lbs torque at 1400 RPMs. I believe it was early 60's and only available in the bigger trucks. They also had a V-12 displacing 702 cid that kicked out almost 600 ftlbs torque.

Saw a cm2500 the other day parked in a field. Thought it was pretty cool.

I’ve never heard of either of those engines.

Interesting

Interesting. I also was unaware of these. It looks like these were mainly used in trucks over 1 ton.

https://en.wikipedia.org/wiki/GMC_V6_engine

We had fuel trucks in the air force with the big v6. Total pos.

Like SA drives or bigger?

Interesting

The V6 was used in the medium duty trucks and the V12 was a heavy duty engine. They were low RPM motors and were well known to break crankshafts. The max RPM was like 5000 and the V12 when tuned up and running good was getting at least 3 MPG.

My Dad had a 1960 GMC pickup with the 305 cu. in. V6 Was a great engine. Had lots of torque and got good mpg and he put over 100K miles on it. Was a very smooth running engine.

That v12 looks like 2 v6’s bolted together.

Back in the 60's when we were building sand buggies, a good friend built his with a GMC big block V6, while mine was a 330 hemi out of a Desoto. Those were fun times!

Maybe in 1960 but later years had crankshaft issues.