1972 GMC 637 V-8 video

[MusicMan70]

From the GMC 6066 site; a posted vid of this Kool engine

GMC 637 cid v8 gas - YouTube

Info from Jolly's site;


637 V8

275 @ 2800 rpm

185 @ 2800 rpm

250 @ 1550 rpm

560 @ 1550 rpm

5.125" - 3.86"

637.0 cu. in.
(10.4L)

7.5 to 1

[C10 - C90 Bill]

Interesting video, but I wish he revved it up a bit, lol !!

I used to drive a '71 GMC 9500 (Conv Cab) with a 637 V-8 back in the early to mid '70's.

I really didn't notice what kind of Trans the truck in the video has, but so far the GMC I drove is the only 637 that I have ever known to have a 10-Speed Road Ranger Trans behind it.

It is actually pretty hard to find a 637 in any Conv Cab as sure enough, the one in the video is a Cab-Over, but I finally discovered a couple of Firetrucks that had some (5 and 2's though).

Bill

[junkmandan3]

Bill-------The R 96 Fuller was an option.

[C10 - C90 Bill]

Dan,

I might have asked you already sometime through the years, but can you ever remember personally seeing or knowing of a 637 V-8 Gas along with the R-96 10-Speed RR before?

[junkmandan3]

Bill------I don't remember if I ever saw a 637 V-8 period, but have seen a number of the V-12 702s.

[C10 - C90 Bill]

Originally Posted by junkmandan3

Bill------I don't remember if I ever saw a 637 V-8 period, but have seen a number of the V-12 702s.

They are pretty rare.

Although I'm a Diesel fan and really not too crazy about any V-8 Gas in a Big Truck, the 637 was somewhat like-able. The worst thing about it is that it would "dog down" pretty quick when fully loaded, even on the slightest grade, that it required a lot of shifting. Which I really didn't mind as I'm one of those crazy ones who likes to shift. Also Double-Clutched every gear, lol.

[special-K]

Those guys missed the mark in that video not having good sound. I enjoy seeing an older truck move around and all,but really like to "hear" those old motors!

[C10 - C90 Bill]

Originally Posted by special-K

Those guys missed the mark in that video not having good sound. I enjoy seeing an older truck move around and all,but really like to "hear" those old motors!

They also have their own unique sound unlike any others.

Bill

[special-K]

That's what I meant. The old motors were more unique from one another back then and now they sound pretty much the same.

[68panelman]

Funny how it almost sounds exactly like the 305 V6 I had, or maybe they both have the same exhaust leak? The one pic of the rear of that 637 shows the same block/piston angle as the V6.

[C10 - C90 Bill]

Originally Posted by 68panelman

Funny how it almost sounds exactly like the 305 V6 I had, or maybe they both have the same exhaust leak? The one pic of the rear of that 637 shows the same block/piston angle as the V6.

Those engines are like a V-6 with 2 extra "cylinders" welded on, but even though look very much alike, they are actually two very different engines. The V-6, especially the big 478, is a "Lugger" that has a ton of Torque. The 637 V-8 is a "Revver" and is more like a Detroit. I'm far from an expert on the internals, but someone once explained to me how different they are on the inside.

They also actually sound very different from each other. It is hard to tell by an idle though.

But the 478 V-6, like most V-6's, would also have less restrictive mufflers from the factory and as recommended replacements, where the 637 had more restrictive mufflers. Once the 637 I drove burnt out the originals, we all we waiting to hear what it sounded like with less restrictive ones, but the mechanic put on the recommended replacements which were like the originals.

Bill

[junkmandan3]

Yes, there's a little exhaust ticking noise on the right side, then on the left side you can really hear the air brake compressor pumping . The chassis was a fire truck as it still has the pump transmission in the driveline. Great to put a regular 3 or 4 speed auxilliary in place of it, like I did on a 1954 model 630 with 503 gas engine. That was another real world project for the local Vo-ed school.