702 GMC V-12 powered '62 GMC 1-ton

[arkracing]

Looks like those back 3 cly's cleaned up well though - that's a good sign

I say paint it - I like black myself. I think Chevy orange will be way to much on that thing (but it does appear to have been orange from the start huh?

[cayoterun]

They were originally red, but sun faded to orange. I'm painting it red/w black accessories.

Shaft still standard and bearings were in good shape. Cylinders cleaned up real good with light honing. All the pistons are back in, except one. Something dinged it up when the head or whatever blew. Off to the junkyards to find a .30 over high altitude. Anyone have one/w rings?
Finding new parts is history, so it's junkyard shopping for them. If I can get a piston, hope to be running in stand in a couple of weeks.

If & when she does run, I'll get my son to post a video/w sound if he can. They have a sound all their own.

Thanks for all the imput.
Cayoterun

[bigtruck81]

Originally Posted by ChevLoRay

Remember when Olds brought out the Toronado in '66? Remember that they used a chain, as it was called, to get the power from the 425 engine to the TH transmission? You could use a version of that to do the power transfer, if you didn't mount it conventionally and use an SM-420 or SM-465 gearbox.

my buddy's 68 had the trans in the correct spot, with what appeared to be a transfer case on the back, IIRC, to transfer the power to the front diff.

[jeffspower]

I would think you could get a new piston from Egge. Where is yours damaged? I've seen some pretty ugly sluggers saved that ended up ok- especially for a low- rpm motor.

[cayoterun]

Burned or broken on top almost down to top ring groove for about 1 inch. How do I find Egge? I've never heard of them here.
Thanks for your help,
Cayoterun

[jeffspower]

http://www.egge.com

They don't show the GMC V- motors in their online catalog- but I'd be surprised if they couldn't get them.

[arkracing]

I have an older hard copy of Egge's catalog and don't see any GMC V-6 motor parts listed. You might be able to call them and see if they can get it -or send them a good one and they can make a new one. They also indicate in thier catalog that it is not a complete listing of everthing that they have or can get.
800-996-3443
Tech/Information: 800-866-3443 or 562-945-3419
www.egge.com

You might also want to try "Kanter" They have a listing for GMC Truck V6 351 (4-9/16" Bore) BUT but when it lists pistons it says that only the 401cid piston (4-7/8") is available.
You might want to call them too
800-526-1096
www.kanter.com

[cayoterun]

Piston: Jeffspower, I don't think I want to try this one, would you? This pic makes the piston look like it has an upturned lip near burned/broken spot. It's not, it a flat piston and the oval is raised a tad.

Truck: What year model is it? It offers more and better set-up than the crew-cab. The crew-cab has no value for this project. This truck has standard clutch set-up, power steering, bed, shorter wheel-base, would be a lot easier for air flow front to back, and keep the work/ratty look, etc. I have the option of either.
Imput?
Thanks,
Cayoterun

[cayoterun]

Hoo-rah! The elusive piston has been found and installed.
Tried all sources mentioned above plus others. Found one in junked motor locally.
Maybe reassembly can get started tomorrow.

If anyone considers trying to rebuild a V-12, be prepared for lots of headaches trying to find parts. Over time, many different bores and types of pistons have been used in these motors. Matching pistons seems to be one of the golden items.
Thanks for all suggestions
Cayoterun

[jeffspower]

Awh heck, a little tig work, some time on a lathe and a little knurling could have saved it

Glad you found a replacement- sounds like you found a needle in the haystack.

[cayoterun]

Jeffspower, Your good with that tig! #10 lookin' good. Heads and pan back on today.
Thanks,
Cayoterun

[jeffspower]

I can't wait to hear it run! It would be cool just to leave on a running stand for a while, just so you could build all sorts of header setups to see what different sounds it would make. 6/1 collector with dual 4' pipes, 3/1 (x2 per side) with quad 2-1/4" pipes, 2/1 (3 per side) into one collector- how about zoomies

[cayoterun]

This is just one of many, many header/muffler setups they have used on them. They are always pointed forward to throw the heat away from the pump, gauges, and the motor while you service it when running. Those exhausts glow red and fire out the end about 2" at night.
Loud, You could hear them for two miles or more. No tall tale.
Cayoterun

This is a different motor, I just marked this motor #10, and in prior post was talking about #10 cylinder on my keeper motor.

[jeffspower]

I used to live 1/2 mile away from a straightpiped Minneapolis- Moline irrigation motor. It would sing me to sleep night after night when there wasn't any rain

[cayoterun]

Anyone want to help time this thing in a few days? It has to be timed one cap at a time from different timing marks on damper in a certain sequence. This pic from another motor.
Getting some of the remaining grease painted too.
One bolt at a time
Cayoterun

[Palf70Step]

That is so cool looking, but my head hurst thinking about you timing it.

That will be wild when you get it into the crew cab!!

[cayoterun]

A friend gave me these this evening for the project.
They are actual GMC truck badges. Very hard to find.
Thanks, Bob
Cayoterun

[cayoterun]

There's a V-12 on e-Bay, item# 230177566730 for sale. He says you can hear a 702 run on utube somehow. I couldn't find it.
Probably be better quality than what I could post, if mine ever runs. I'm gaining---one bolt at a time.
Cayoterun

[sick69]

Here is a link to a b-702

http://youtube.com/watch?v=BX_zDx-aiog

Frank

[cayoterun]

We've about reached the point-of-no-return on the motor, at least. We have a complete 702. Just noticed the hat---it was an option in '64. Still lots of adjusting, tweaking yet. Still have a flywheel-starter problem to iron out. Just take some more shopping.
Plan to take 7-10 days off for R&R in the TT.
Food for thought: As said early in this project, there's no telling where this project would lead.
I bought the '62 GMC from a long time friend last night. He bought it new and still has a good title. Good titles are valuable property in our state. The crew-cab as well as the 78? chev yellow flat-bed, titles are possible, but a hassle.
Based on ya'lls imput, local availability, and cost, why not take the frame and bed from the '78?, graft the cab and front clip of the '62 GMC? I have access to other pickups of the same vintage for the doors, hood, and then it would be a smooth cab & clip. We would end up with a totally legitimate '62 GMC 1ton with a V-12?
Progress: One bolt at a time
Cayoterun

[cayoterun]

All V12s are not the same.

The starter was missing on this engine. Picked up couple from junkpiles. Starter drives were too short and sit too far from the ring-gear. Measured about 6-7 and they were the same. Finally measured flywheels, mine was 16 1/2" diameter, and for a double disc clutch, the rest 15 1/2" and for single disc. Had to spend the day changing the flywheel and housing, so the small starters would work. No telling what this engine was originally built for, and ended up new on a pump.
May get to test spin on starter tomorrow, but still have to rewire around the safety switches, put propane kits in carbs, and other odds and ends before the big crank attempt.
Just hope I got all the water and oil passages cleaned out. Glad I have alot of junk motors to rob and farmers will let me do it. I think they are just wondering if this thing will ever fly,-- I am too, but it's fun.
One bolt at a time, then do it again-
Cayoterun

[Palf70Step]

I like the idea of it going into the 62, but either (any setup) would be cool for that!

[cayoterun]

It looks like the '62 will be in the end product somehow due to the title. He called today and said it was in his hand. It was last tagged in '72. He put over 200,000 on that V6, before it shucked. He's elderly and been a great friend, so pickup and motor combined will also bring back memories of many good crops as well as some bad ones.
Cayoterun

[Storm Chaser]

I wish I could come across one of those engines. Just watching yours take shape gives me images of one installed in a lengthened T-bucket frame. I can just see it now with four chrome valve covers...

[cayoterun]

They are really durable, easy to work on, simple, except ignition, then it's not bad after learning the sequence. Left cap feeds left bank, Right cap right. If one side quits, it will run on 6 cylinders. Anyone here who has used one talks about them like an old favorite workhorse. They sure like fuel, tho.

The T-bucket with engine out in the open would make one whale of a show-piece. The main disadvantage is dealing with the weight of them and tranny. I'd like to see someone build one like that.


I like to watch your beast develope. It's going to be a nice one. Keep twisting those bolts.

Thanks to all for your support, ideas, and comments.
Cayoterun