[Jack Gifford]

Any other PY members have a GMC that came with a Pontiac V8? Please post here what you've got, how you're using it (them?), etc. Thanks.

I'm in the process of re-doing my '59 shortbed Fleetside. The original 336 engine was already gone when I bought the truck, so I've built a '58 Tri-Power engine for it. I'll try to post a picture- in its former ugly orange paint! No, I won't repaint it orange- it will be the same blue as my "Challenger" minirod, which has an alky-injected Pontiac 400 in this picture.

I know that PY member Bill Hanlon has a very pretty '57 GMC with a 347. Rather than get the details wrong, I'll ask Bill if he wants to tell us about it?

[Bill Hanlon]

Originally Posted by pontiac jack

I know that PY member Bill Hanlon has a very pretty '57 GMC with a 347.

I don't know if I would refer to any '57 GMC as "pretty".

Since 1990 my daily driver has been this '57 GMC 102 (stepside, long wheelbase) which still has its original Pontiac 347" V8 and Dual-Range (like on pre-56 Pontiacs) Hydra-Matic. Current mileage is 185K, adding about 5K a year. It was stock when I bought it. Upgrades since include disk brakes on the front, alternator, A/C, HEI, seating from a late '80s Chevy truck, CD player and 3 point belts. In 1998 I had a bunch of rust repair done and then had it painted using a '97 Honda color "black currant" which is a real dark purple. I do all the mechanical and electrical work, but left the paint and body to the pros.

This weekend my brother and I are installing power steering.

I really enjoy this combination hobby and unique mode of transportation.

[Jack Gifford]

I say "pretty"! There's also something very "cute" about an in-dash 4,000 RPM tach! Thanks for sharing.

[Bill Hanlon]

The tach is a Sun SuperTach II. After removing the bezel it is about 1/8" too big in diameter to fit into the GMC's tach hole. A little buzz with a dremel tool fixed that.

I refaced it by removing the face plate, turning it over and spray painting it flat black on the back (now my new front). The amount of swing from zero to 8000 RPM on the original face is almost identical to the amount of swing on a GMC 80 MPH speedometer. I cut the outer tick marks from an 80 MPH GMC speedomemter decal and applied them to the newly painted surface. Then cut 0 1 2 3 and 4 digits from the same decal kit and applied to the new face. Used a fine black "Sharpie" to paint the edges of the cut decals so they would look black.

The trick in making it a 4000 RPM at full swing is simply to move the selector switch on the back of the tach from 8 cyl to 4 cyl.

The original GMC tachs were actually 0-5000 Sun tachs with a 90 degree swing and external Mercury battery powered "sending units". My Hydra-Matic upshifts at 3800 RPM and there is no way I'd ever try to get this beast above 4K in high gear.

By the way, the engine was running when the picture was taken. It really does idle at 450 RPM.

[63 Pontiac]

That is a nice looking truck, GMC's have lots of character.

If I had it to do all over again my old '56 Chevy shortbed would've gotten a spare 389\TH400 combo instead of the SBC 305\TH350. I miss that truck...

[Bill Eveland]

Jack, is this what your looking for? I could only get one. Hopefully the paint has helped preserve the metal from pitting.

[Jack Gifford]

Bill- PM'd you.

[timbo]

What year did GMC start using the Pontiac engine? I have a 51 GMC and am thinking about putting a Pontiac motor in it. Thanks

[Jack Gifford]

Originally Posted by timbo

What year did GMC start using the Pontiac engine? I have a 51 GMC and am thinking about putting a Pontiac motor in it. Thanks

Pontiac V8 was optional beginning in late '55 GMCs, called 'second series'. The 'first series' 55s were just like the 54s. '59 was the last year the V8 was offered. For '55/56/57, the GMC V8's were the same displacements as Pontiac cars- 287/316(322?)/347, respectively. For '58/59 they were 336 c.i.- the '58 being a small-bore version of the car's 370, and for '59 a small-bore 389.

[Jack Gifford]

I noticed a couple of interesting GMCs on E-Bay tonight- a white '56 in VT with a 455-HO, and a red '57 in Alaska with original 347 & Hydramatic- with a 'buy it now' price under $4,000!

[Jack Gifford]

So... I guess this is called 'progress'?! Yeah, I started disassembly way back in late summer, and by a week ago had only gotten from the front bumper back to the firewall. That was due to a 'disciplined' approach of dealing with every little piece as I removed it- restoring any piece that is salvageable- cleaning/straightening/painting brackets, etc., locating a source for the un-saveable stuff, and taking sheet metal to the body/paint shop. A little more cutting/welding on the inner fenders and I will truly be done back to the firewall- ignoring the chassis, which I won't start until all non-chassis items are dealt with.
However, I had to change my operating-mode- my spouse will want that parking space as soon as the snow hits! So I'm now trying to strip off enough pieces to keep me occupied all winter, without having to work in an unheated barn.

P.S. Anybody else using an aluminum hemi as a dust collector???

[Jack Gifford]

bump

No other GMC Pontiacs out there????

[Jeff Walker]

Does a 455 powered '86 GMC Suburban count?

[Jack Gifford]

I originally said "Pontiac from the factory", but don't mind broadening this thread to include GMCs like yours! (Rats! I don't get to mention my Pontiac-in-'83Chev-Suburban). Got any pictures of your 'Burb?

Any more Pontiacs-in-GMCs??

[Jeff Walker]

Here's a couple pics of the Poncho-Burban. I mainly use it for towing the race car.....when it's together.

[gregneun]

I ran into one today. Let me know if there is any interest in the block or the heads. See my head posting about 531395 heads. The guy has bored this block to a 350.

[Jack Gifford]

Want to share anything about your '57 GMC? Even if it's Jimmy-6 powered, GMC has been closely aligned with PMD over the years.
Oops! I see now that you do have a Pontiac engine.

[Steve Barcak]

Hey Jeff,
How did that swap go? Did you do it?
I inherited my brothers '84 1 ton dually 4wd. I use it for heavy towing, I have a 48' 3 car trailer. It has a bow tie 502 in it that has been upped to 516. I have pondered putting in a Pontiac but, did like the idea of using a cast crank. Now that forged cranks are available and reasonably priced, I am thinking about it again.
What did you use for exhaust? mainfolds? Headers? if so, for what chassis?
How about the fan shroud? What shroud worked with the Pontiac? Cooling is important here in the desert.

thanks for your input.
Steve Barcak www.pontiacheaven.org

"Real Pontiacs only....no corporate nonsense!"

[Steve Barcak]

Hey Jeff,
How did that swap go? Did you do it?
I inherited my brothers '84 1 ton dually 4wd. I use it for heavy towing, I have a 48' 3 car trailer. It has a bow tie 502 in it that has been upped to 516. I have pondered putting in a Pontiac but, did not like the idea of using a cast crank. Now that forged cranks are available and reasonably priced, I am thinking about the Pontiac swap again.
What did you use for exhaust? mainfolds? Headers? if so, for what chassis?
How about the fan shroud? What shroud worked with the Pontiac? Cooling is important here in the desert.
Also, my trans is a 1 ton 4wd. I would have to see what the tail shaft length is to compare with a pont trans...or rebuild a trans with the existing output shaft in the pont case.
thanks for your input.
Steve Barcak www.pontiacheaven.org

"Real Pontiacs only....no corporate nonsense!"

[Jeff Walker]

Originally Posted by Steve Barcak

Hey Jeff,
How did that swap go? Did you do it?
I inherited my brothers '84 1 ton dually 4wd. I use it for heavy towing, I have a 48' 3 car trailer. It has a bow tie 502 in it that has been upped to 516. I have pondered putting in a Pontiac but, did not like the idea of using a cast crank. Now that forged cranks are available and reasonably priced, I am thinking about the Pontiac swap again.
What did you use for exhaust? mainfolds? Headers? if so, for what chassis?
How about the fan shroud? What shroud worked with the Pontiac? Cooling is important here in the desert.
Also, my trans is a 1 ton 4wd. I would have to see what the tail shaft length is to compare with a pont trans...or rebuild a trans with the existing output shaft in the pont case.
thanks for your input.
Steve Barcak www.pontiacheaven.org

"Real Pontiacs only....no corporate nonsense!"

The swap is a piece of cake...and yes I did it. I also have a 78 Chevy 4X4 that I put a Poncho 400 in years ago.

For motor mounts, get them off any 73-77 A-Body or Grand Prix. The Frame mount with the rubber is even still available from NAPA. Exhaust manifolds will work from the same car too. On my Suburban I picked up a set of Heddman short style headers (thanks Grandville 455) that are for a 2nd gen firebird. I had to do some work on the LH collecter outlet to clear the lower control arm but this shouldn't be a problem on a 4X4. As for a fan shroud I used the stock shroud with a bit a trimming around the PS pump.

As for your transmission, I am guessing it is a TH400? What you will need to do is get a BOP case and put you internals into it. The 4X4 output shaft is by itself.

If you have any other questions about this swap, feel free to email me at gtojw@westriv.com .