The Stovebolt Site Forums The Parking Lot Big Bolts GMC v 12

Does anyone have an idea how much a twin 6 (v12) is worth in running condition? Owner claims it ran 5 years ago. It was an irrigation engine so I'm sure it has lots of hours. What would it cost to rebuild something like that, assuming no major parts were needed?

There is "some" info on this site about them but you'll likely find more at the GMC site. What do you consider a major part? The 351 pistons, valves, heads, etc were essentially the same so that can be a guide.

First of all, parts for the v6 engines are not cheap because they were never a whole lot of them built and therefor parts are high. And then remember you have 12 holes instead of 6. You must double the cost of everything. There are people who are fascinated by them and pay big money for them. If I had a line on on one that was reasonable, I would consider buying it and trying to get it to running and advertising it for sale as a runner. A lot of it depends on why it was taken out of service. If it had major problems, it could be a major ordeal. If it was taken out of service because it wasn't economically feasible to run it, it may be in pretty good shape.

Judge what it's worth to you and make your own decision.
I've seen them cheap to free and really expensive too, all depends on the situation.

I had one I paid just over scrap price for, and while I had a little fun with it the parts to get it running were going to be quite expensive and I sold it as a basket case without any new parts. I would not have bought it had I better known the condition ahead of time.

I say if you think it's really cheap and you want one to play with then buy it. But if you don't know what to do with it or think it's a little expensive then leave it alone.

Grigg

Offer scrap iron price unless the owner is willing to crank it up for you and let you hear it run, check compression, etc. It would make a real conversation piece in a hotrodded cabover, or something similar. I seem to remember somebody using a marine V-drive unit and mounting one of those engines behind the cab of a big bolt cabover, maybe? Oddball setup, but definitely different!
Jerry

By major parts, I mean crank or cam or a new set of pistons; something other than rings, bearings and gaskets. The asking price for the motor is $350. I wonder if it would fit in a '54 6100 engine compartment?

The major parts you mention would be really big bucks. A V6 can be fitted into a 54 GMC in fact GMC sold a kit to do that some time in the 60's. I don't know where in the world you would put the other half of the engine.

It will not fit into the '54 6100 without a severe cut in the firewall and that will leave your toploader tranny stick shift somewhere behind the cab so you'll need really long arms and no back window if you plan to use it. Alternatively, you could remove the radiator and shove it all the way forward and then mount the radiator somewhere else with an electric fan, but I still think you'll have to carve up the firewall to make it fit even without the radiator.

Cranks are not made and are about the hardest part to find for these after the camshaft and block. These were a steroidal evolution of the big block 351 GMC V6 engine.

Here's a video I took two years ago of a display V12 at the ATHS National Meet in Hutchinson, Kansas:



And here's the one that our oldGMCtrucks.com forums member "Locomotive Breath" built for his truck.


Of course he's also got a Mustang drag car with a tank engine in it, so putting big long motors in small spaces doesn't seem to concern him at all!

Have you seen this truck ? Or what about this one? Lots of V12 vehicles on youtube.