84 GMC C2500, V12 powered

[Dieselwrencher]

Cayoterun, did you happen to see that V-12 in the 55-57 4 door that was posted in a group of car show pics on this forum? It was pretty cool. I don't think the guy lengthened the front clip at all. If I remember correctly he recessed the firewall a lot. Anyway, good luck on the new build and nice score on another V-12!

[Stitch]

this is gonna be sweet...

[cayoterun]

Originally Posted by Dieselwrencher

Cayoterun, did you happen to see that V-12 in the 55-57 4 door that was posted in a group of car show pics on this forum? It was pretty cool. I don't think the guy lengthened the front clip at all. If I remember correctly he recessed the firewall a lot. Anyway, good luck on the new build and nice score on another V-12!

I saw some pics of a '55 Chev sometime ago, and I believe he had opened up the firewall and let it come back into the passenger compartment. It's been a good while ago since I saw it, but don't remember where.

Cayoterun

[Dieselwrencher]

If I see it again, I'll post it in here for you.

[cayoterun]

It seems like the one I saw was in Australia, and where the body was joined together, it had bolts or sheet metal screws. The seams looked like a ship or big storage tank that had been riveted together.
If you find yours, I'd like to see it.

I thought alot about letting the motor go back in the cab, but that thing would probable be so loud, hot, and hard to work on, you might not be able to stay in there. Those things generate alot of heat.

If I posted some side pics of the '84, would someone see them here and photo-chop it with the cab slid back and long hood? Or should I make a thread with a request in the photo-chop forum?
Thanks,
Cayoterun

[Dieselwrencher]

Here you go. Post 308.
http://www.67-72chevytrucks.com/vboa...292529&page=13

[cayoterun]

I don't believe the motor in the '55 is a GMC V-12. I believe the GMC V-12 was mounted on an open "show and tell" stand. It sure was sharp all dolled up like that.
The motor in the '55 is extended back in the passenger cabin, but it looks like a completely different configured motor to me. It looked like it was alot lower profile motor, but my eyes may be playing tricks on me.
The 12s are a real tall motor measured from bottom of oil pan sump to the top of the carbs. If I think of it, I'll measure the motor from top to bottom. I only had 8" of clearance from pan to ground on the other truck and still had trouble covering it with a hood.

Thanks,
Cayoterun

[Dieselwrencher]

To me it looks like it has modified Hemi valve covers. But, IDK, it does have 6 cylinders per side, but you can't see the plug wires at the inner part of the intake to head area like the V-12 GMC pictured.

[cayoterun]

I reread your posts, I misunderstood, I thought you were saying the '55's motor was a GMC, too. Please forgive the "senior moments".
I wonder what kind of motor that is? It's sure a mean looking rascal. Lots of work went into the headers alone. Could that be a V12 Cadillac like the military used in some of the tanks in the '60s?
I drove an Armored Personel Carrier in '63 at Ft. Sill, Ok for awhile that had two 6 cylinder GMC truck motors in them with two auto trannys. That was a wild drive arrangement. Linkage adjustment nightmare.

Cayoterun

[BLE 'BURBAN]

Hmm How's about putting that thing under the hood of an old 73 - 77 Monte Carlo/Pontiac LeMans? They both had about 3-4ft of gap between the fan and radiators in them. Should be plenty of room for that beast.

[cayoterun]

Originally Posted by BLE 'BURBAN

Hmm How's about putting that thing under the hood of an old 73 - 77 Monte Carlo/Pontiac LeMans? They both had about 3-4ft of gap between the fan and radiators in them. Should be plenty of room for that beast.

The 12s measure an even 5' from tip of water pump shaft to end of flywheel housing. Then you have to add radiator & fan in front, then hogs head and tranny in rear. They're a long, tall, heavy, (1500# dry), motor. I had to have 6-1/2'+ on the other truck. You also need access to the distributor on the rear of some kind. It has three timing points on the dist. One in each dist. cap, and the conventional horizontal adjustment.

Cayoterun

[cayoterun]

Originally Posted by locomotive breath

Great find, I knew you couldn't stay away from em for long. I'm pretty sure some of the GM 3/4 tons in that age range came with a 14 bolt GM rear that you can still get 3.42 gears for.

I'm pretty sure this '84 has a 14 bolt. I don't have it home yet to really look it over good.

Have you got the electronics hooked up on your 4l80 yet? If so, how big a hassle was it to hook up?

Is there a non-electric auto overdrive out there that would hold up behind a 12? I'd sure like an overdrive, and use the same adapters that we used last time. This motor does have the flywheel drive plate. They are getting scarce too.

I, also, have a Spicer 5spd over manual that would be good if I could come up with some adapters for it.

[spudz]

MAN! I just found this...I cant believe you are doing it again! I cant wait.....

[cayoterun]

Originally Posted by BLE 'BURBAN

Hmm How's about putting that thing under the hood of an old 73 - 77 Monte Carlo/Pontiac LeMans? They both had about 3-4ft of gap between the fan and radiators in them. Should be plenty of room for that beast.

I measured the height this morning and it's 44" from pan botton to top of air cleaners. It would be less if gas carbs were used. I'm a dyed-in-the-wool LP fan, so plan to stick with it.

Spudz: Can't seem to kick the addiction and after 44yrs with the same gal, it seems to have a calming effect on our marital relationship to tinker in the barn, rather than being a couch potato.
Jump in here and help us anytime decide what to do with this pile of junk yard refugees. The last monstrosity changed directions a dozen times during three years.

Cayoterun

[locomotive breath]

Originally Posted by cayoterun

I'm pretty sure this '84 has a 14 bolt. I don't have it home yet to really look it over good.

Have you got the electronics hooked up on your 4l80 yet? If so, how big a hassle was it to hook up?

Is there a non-electric auto overdrive out there that would hold up behind a 12? I'd sure like an overdrive, and use the same adapters that we used last time. This motor does have the flywheel drive plate. They are getting scarce too.

I, also, have a Spicer 5spd over manual that would be good if I could come up with some adapters for it.

The Compushift kit is very easy to hook up, but it is kinda expensive. I guess expensive is a relative term though. The TH200-4R could be beefed up enough to hold it for awhile, especially if you didn't beat on it too hard. They are non-electronic and have a .67 OD ratio. I'll probably catch some flack over this but I think dollar for dollar they are stronger than the 700-R4.

[cayoterun]

Originally Posted by Palf70Step

You are officially moved, so let us see your mess

The shop is starting to look normal again.

Ran the NEW motor today about 2hrs flushing the cooling system. Circulated degreaser soap thru it last. It sure bubbled the suds out the surge tank. Never let the temp get over 160.
Left the water in it tonight, will pull oil drain plug tomorrow. Hope there's no water down there.
Ran and started good. I'm well pleased so far.

Cayoterun

[Dieselwrencher]

Very nice!

[locomotive breath]

Man that thing sure cleaned up nice. Glad to hear it's running good.

[cayoterun]

Need advice, again.

What's a good non-metallic, (won't conduct electricity), material that I could use for a heat shield on the rear exhaust pipes???

These sit about an inch from starter and oil filter. I can slot the bolt holes and gain more clearance, but not much.
I'd like to use these old original pipes, and leave the oil level sight gauge for a conversation piece if I can.
Thanks,
Cayoterun

[rod86]

nice!
oh an by the way that 55 chevy that was built in australia you mentioned has a rolls royce merlin v12 in it...

YouTube- Merlin V12 Powered 55 Chevy

[cayoterun]

Originally Posted by rod86

nice!
oh an by the way that 55 chevy that was built in australia you mentioned has a rolls royce merlin v12 in it...

YouTube- Merlin V12 Powered 55 Chevy

Yep, that's the one.

[spudz]

Originally Posted by cayoterun

Need advice, again.

What's a good non-metallic, (won't conduct electricity), material that I could use for a heat shield on the rear exhaust pipes???

These sit about an inch from starter and oil filter. I can slot the bolt holes and gain more clearance, but not much.
I'd like to use these old original pipes, and leave the oil level sight gauge for a conversation piece if I can.
Thanks,
Cayoterun

maybe fiberglass heat wrap?

[cayoterun]

Originally Posted by spudz

maybe fiberglass heat wrap?

I ground the welds that held the pipe to flange and moved the right side pipes out. I have about 5" clearance from the starter now. The left side pipes were already slotted, so have about 3" clearance from oil filter.
I have enough room now to use a metal heat shield.

I found and ordered a 50' roll of heat wrap from Summit today too.
With both metal and wrap, it should be in good shape.
Thanks,
Cayoterun

[1985-GMC]

I'll have to watch this one after seeing the last one you built, cant wait! What transmission are you going to run?

[cayoterun]

Originally Posted by 1985-GMC

I'll have to watch this one after seeing the last one you built, cant wait! What transmission are you going to run?

Transmission: Probably an automatic overdrive. We've found a simple adapter system that's worked well on these two, so will stick with it.
Rap-'em-papy is using a 700-R4 with fast gears and its doing well. He can run hi-way speeds @ 1000-1200rpm. I sure don't intend to beat the driveline up and soft-pedal the throttle as it shifts thru the gears. Balaur has a T400 in it. Too slow.

Rap-'em-papy was in Kansas City for a Labor Day show, so came on out to meet Balaur at the museum. What a sweet truck. Runs, drives, and looks great! Our neighbor who bought the motor new and used it all those years was really pleased to see how his old irrigation motor was being used.

The quick photo-chop was one of the ideas we talked about while they were here for the '84.
Cayoterun