637 ci

[gmcft]

Where can I get any information regarding the GMC 637CI V8 engine?

[BillT]

What info are you trying to find on it?

Some of us may be able to help.

[gmcft]

We need all of the engine specifications to do a complete rebuild.

[BillT]

A quick search found this:

http://www.oeltd.net/doc/GMC_Manuals...%20X-6A-01.pdf

Although it is dated July of '67. I believe the 637 started in 1966.

[gmcft]

I am a newbie in regards to old trucks.

We will start the project this coming summer.

Thank you for this information. It is very much appreciated.

[BillT]

Keep us posted on your progress once you get started.

[2-Ton]

Started my 637 today. It's in a 1967 GMC ladder truck.
The 637 came out in 1966, it replaced the V-12 twin six.
Some on here don't like posts about the 637. They feel it does not fit in with the 60-66 group. I may have a shop manual on it though. Join "Stovebolt.Com", They will help you out a lot more!

[2-Ton]

Looks like Bill nailed it!

[POWERSTROKE]

I know Chevy used a few TOROFLOW engines, did they use any Big V-6 or the 637 CID V-8?

[Dave Boboltz]

From POWERSTROKE's question, regarding Chevrolet's use of the GMC designed BB V6 and its variants, including the 637 V8:

From an Encyclopedia of Chevrolet Trucks, not my data:

The first use of GMC designed BB engines in Chevrolet trucks was 1965. The engines were Toro-flow 478 engines in 60-80 series Conventionals, Low cab forwards, and steel tilt cabs.

IN 1966, there was a new short Low cab forward and it used 401-478 BB V6 gas engines. The biggest steel tilt cab introduced the toro-flow 637 along with the toro-flow 478.

In 1967, in addition to previous usages, 70/80 series series used 401/478 gas V6 and toro-flow 637.

1968 through 1970 basically unchanged.

1971 usages remained but GMC designed BB V6 engines were losing popularity to 366/427 Chevy V8 in Chevy trucks due to same power and less cost, along with reputation for better fuel economy (not my words).

1973 brought new medium duties and Chevy released 305/379 BB V6 gas. HD conventionals used 432/478 V6 gas engines.

1974 was the last year for any Chevrolet trucks to use the GMC BB V6 or its variants.

I do not see any use of the 637 V8 gas in any Chevrolet trucks. Since most of the Chevy HD trucks and all steel tilt cabs were built in the GMC plant in Pontiac, it is possible that a Chevy might have been built with a 637 engine on a SEO (Special Equipment Option).