57 GMC conversion kit

[thatz4u]

Does anyone make this & where can I get it? thanks

[dimaxion]

Shawn Carpenter . He does nice work . The listing now is for a '57 Step Side . I have this and his '68 GTO conversion. I reccomend him . You can find him on <rocketfin.com> , scroll down to -model car links , right click . The listings are alphabetical . Thanx..

[Aaronw]

I didn't know he did a '57 GMC. I have his 1950 GMC conversion and it is nice. I'll have to add the '57 to my get list.

[Longbox55]

You will need to gather up a few extra parts that aren't in the Shawn Carpenter conversion if you're doing a stock GMC. Back then, GMC didn't use Chevrolet engines and axles in their US spec trucks, they had their own engines for 6 cylinder, and used Pontiac engines for the V8 option. The rear axles were Spicer 45s for the 1/2 ton, which is similar to a Spicer 44, and Spicer 60 for 3/4 ton. 1 tons used the the same Eaton HO72 that the Chevy used.

[Aaronw]

I'm too concerned about axles, but do you know which Pontiac V-8 they used, and is one available in a kit? I can't think of many 1950s Pontiac kits out there.

[lizardlust]

Am I mistaken in thinking that the optional motor in AMT/Ertl's 1936 Ford tool was close to the era of Pontiac motor in the 55-57 GMC(347 c.i.)??

[Chuck Most]

Didn't they run Oldsmobile engines as well? Or was that earlier on? (Or never at all?)

[Longbox55]

GMC did run Oldsmobile flathead 6 cylinder engines pre-WW2, mainly in the lighter trucks (1/2-1 ton), though the Special Delivery used a Buick based ohv 6 cylinder (the Special Delivery was originally a Buick badged vehicle prior to '27). By '41, GMC had their own inline 6 for light trucks, the 228, 248, 270, and 302 engines. When the V8 trucks came out in '55, GMC used Pontiacs, but with the '56 introduction of the Tandem option, they did use Oldsmobile engines in the heavier trucks. The use of Pontiac and Olds engines ceased in '60 when the GMC V6 was introduced. The 270 inline 6 did carry on for a few more years in the Step Vans.

For some more details on the differences, here's a link to the '55-'59 GMC Maintainance Manual.

http://chevy.oldcarmanualproject.com/gmc/5559mm/index.html

[charlie8575]

Am I mistaken in thinking that the optional motor in AMT/Ertl's 1936 Ford tool was close to the era of Pontiac motor in the 55-57 GMC(347 c.i.)??

Yes, Kurt, with some very minor modifications, that Pontiac 421 can be made to look like a 287-370 cu. in. engine.

I wasn't aware GMC had a unique block for the 6. I just thought they had a slightly bigger displacement on a Chevy block.

Charlie Larkin

Edited August 12, 2011 by charlie8575

[Longbox55]

At first glance, the two engines are similar in appearance, but once you look closer, there are many differences both internal and external. The GMC engine is about 2 1/2 inches longer, with different manifolds to match. The oil filter is also in a different location, mounted on the passenger side at the front of the block, instead of on the front part of the intake manifold (trucks only). I beleive that the filter, while still a bypass style, was standard equipment on the GMC, Internally, the GMC was more robust, with larger crankpins and full pressure lubrication. Chevrolet didn't get full pressure oiling until the '53 Powerglide cars, manual transmission cars and trucks got it in '54. The GMC also had a better breathing head with a better combustion chamber. Some even had hemispherical combustion chambers in '41.

[Danno]

Hey, Longbox,

Speaking of the GMC V-6, is there a decent 1/25 engine that would appear like the '64 GMC V-6????

Thanks!

(Emoticon indicating "Live Forever, early GMC V-6's!" here.)

[Longbox55]

Not that I'm aware of. However, if you need reference material for one Jolly Goodfellow's (yes, that' his real name) site is the best one out there. http://www.6066gmcguy.org/

[Danno]

Thanks!!!

[Chuck Most]

I want two so I can make the V-12!

[Danno]

Not that I'm aware of. However, if you need reference material for one Jolly Goodfellow's (yes, that' his real name) site is the best one out there. http://www.6066gmcguy.org/

Fantastic site, Bill! Thanks for sharing it. I've been engrossed in it ever since you posted it. Studying ... studying ... studying ...

I've learned an awful lot that I never knew about my long-dearly-departed '64 GMC V-6 Widebed Heavy-Half! God, I miss that old truck! We spent 19 years together, hauling all kinds of gawd-awful stuff all over the dang place!

(Emoticon indicating 'Dan's getting all emotional about one of his old rides again' here.)

[Aaronw]

I've considered making a GMC V-6 by loping off 1/4 of a 454. I don't know that it would be very accurate to the more knowledgable but it should at least provide the basic size and shape (340 ci instead of 305 but it was supposed to be a beefy motor) so should be close enough to fake it with a little cosmetic surgury.