The Stovebolt Site Forums The Shop Area Engine Shop What engines did Task Force GMC's come with?

I am curious to know what kind of engines these trucks came with. In my price guide it only lists them as having v-8's, I assume pontiac engines, but had GMC stamped in the valve covers. Was that the case for all, or did they come with straight 6's as well? 235 and 261 chevy's or were they pontiac's as well?

The '55-'59 GMCs, which were called the Blue Chip series, were available with a 6 cylinder in addition to the Pontiac sourced V8. The 6 was actually a GMC manufactured engine, rather than a Chevrolet or Pontiac sourced unit. The guides usually only list prices for "loaded" trucks, though most of the better ones will give a side note such as "deduct xx% for base engine".
The above information only applies to US spec trucks, Canadian GMCs used Chevrolet engines to my knowledge. One more note, some of the larger GMCs (beyond the scop of most price guided) used Oldsmobile sourced engines, with the Chevrolet counterpart using Buick engines.

the price guide must be a modern thing to value old vehicles, they like to consider top dollar models .... the Blue Chip series [not Task Force] had a number of GMC 6 cyl engines, not shared with Chevy, but specifically GMC division engines

Bill

So am I! GMC never made a "Task Force" truck... that was a chevy advertising thing.

GMC called the 1955-1959 trucks "Blue Chip Money Makers". It is common to refer to them as "Blue Chip" trucks.

As far as engines... a GMC 6 cylinder was the standard engine. It would have been 248 inches in 1955, and 270 inches in 56-59 light duty trucks.

1955 Saw the introduction of an optional v8 for both chevy and gmc trucks. Since GMC did not have their own V8 they used the pontiac engines in light duty trucks, and the oldsmobile engines in heavy duty trucks. I'm not certain where the break was in size so I will answer this question assuming you want to know about the light duty trucks( 1/2 ton through at least 1.5 ton)

1955 gmc was a 287 pontiac motor, but advertised as a 288
1956 was a 316 pontiac motor
1957 was a 347 pontiac motor
1958 was the first real gmc V8 it was a debored Pontiac 370 to come up with 336 inches.
1959 gmc used the Pontiac 389 platform, but again debored the engine to come up with 336.9 inches, but still commonly called a 336.

These early Pontiac motors are differnt from the later Pontiac motors in a couple of significant ways.
1. These motors are reverse cooled. Water is sent to the head first and the block second.
2. The 1955-1960 pontiac motors and the 1955-1959 gmc v8s share a bellhousing mounting pattern that is different from the rest the pontiac V8s. This means you can't simply bolt any BOP bellhousing up to the motors.

Finally GMC wasn't stamped on the Valve covers. A simple GMC decal was placed on the Valve covers. It was the same color as the GMC motors which is a red orange.

Thanks everyone for the great info. Now I know to call my 59 a "Blue Chip". I incorrectly assumed they were called task force since they are identical cabs, etc. Thanks again everyone.

Well now we need details!

I have a 59 gmc 1/2 ton long bed with the original factory Power Steering. Although my truck came from the factory with a HydraMatic transmission, a previous owner swapped it for an sm420 4 speed. I swapped the 4 speed for a 5 speed NV4500.

My truck also came with the 336, but it was tired so I put a 1959 pontiac 389 in it's place. I had the 389 bored and stroked to come up with 447 inches. Of course I had to put the 1957 Pontiac tripower manifold on it because it was just sitting in the garage collecting dust. The engine swap was virtually a bolt in deal.

I had this 59 GMC 3/4 ton, long box stepside given to me by a nice lady. I stocked her pond with some northern pike, and she gave me the truck in return. Not a bad trade! The truck is missing its engine, but everything else is there. I was going to use it as a parts truck for my Dad's 59 3/4 ton long box fleetside. But now I am thinking of having my son restore it, while I work on my Dads truck. The cab is in great shape, very little rust above the windshield, and the floor is in excellent shape, as well as 3 out of 5 of the door hinges. And the doors are in great shape as well.

oughta put that one on ebay, worth a bundle, not many of the 5 hinge models left

Bill

I gotta stop typing in the dark! LOL

Saw this post and wanted to see if you could verify some info. I have a 1957 GMC.but the 347 engines block is cracked. I have access to a 1959 389. Is this a bolt in? I am reading mixed material on the 1959 389 being the first year for side mount.

59 and 60 389 will bolt right in no problem. Task Force .= Chevy. Bluechip =GMC

Pontiac B & S (all 10.25" deck height, 4.62" bore pitch, 6.625" rod):
287: 3.750" × 3.250"
316: 3.9375" × 3.250"
336.1: 3.875" × 3.5625"
336.9: 3.78125" × 3.750"
347: 3.9375" × 3.5625"
370: 4.0625" × 3.5625"
389: 4.0625" × 3.7500"

There is actually a Pontiac V8 "small block", the same basic engine with reduced 9.143" deck height for the 265" and 301" engines.

More data on my site here: http://victorylibrary.com/mopar/m-table.htm

Check out pontiacsafari.com for a lot of info on the GMC Pontiac engines. I believe, according to what info I have gathered while searching for an engine for my '55 Chieftain that the '59 model 389 is a bolt in, as is the '60 model year 389 as both have the front mount. The biggest difference being the 1960 didn't have reverse cooling.