The legendary V12 702 GMC

[Americanrider]

I was J-yarding while visiting family last month and found this on display. It's in Nampa Idaho, never asked if it was for sale, even if it was I could not buy it. But it's the stuff dreams are made of..... Would love to hear it run

DATA PAGE: http://www.6066gmcguy.org/TwinSix.htm

Engine Model Twin-Six 702 V12

Gross Horsepower 275 @ 2400 rpm

Net Horsepower 250 @ 2400 rpm

Gross Torque lbs. ft. 630 @ 1600-1900

Net Torque lbs. ft. 585 @ 1600-1900

Bore - Stroke 4.56 - 3.58

Displacement 702.4 cu. in. (11.5L)

Compression 7.50 to 1

Oil Capacity 14 Qts, w/filter 16 Qts

Dry weight 1485 lbs.

[krue]

The torque specs are cool, but 250 hp? wow

[wolfthing2000]

I have a 52 GMC COE with the 302 straight 6 and one of the truck manuals that |I fpund has this engine in it. What a power plant. I would love to have it!!! Do you have any ideaw what they want for it.. There are certain people who would purchase at any price.!!!!!!!!!!!!!!!

[72armyswbtruck]

That's at the infamous
Jalopy Jungle in Nampa Idaho off Garrity Blvd, it has been out front for years
Also has a cool corvair out front sticking thru the fence

[QKENUF4U]

there are guys in cali making v-16's (two 350's welded together) totally available and for sale $$$$$$$$$$ read about them in HOT ROD or some mag like that a few years back. i guess they are good enough at it you cant even tell where the weld is.

[zeeklu]

http://www.6066gmcguy.org/TwinSix.htm This a pretty cool site. Chris

[chevy_fatman]

That's Would love to have one just like that just to prove desbelievers wrong!!

Originally Posted by QKENUF4U

there are guys in cali making v-16's (two 350's welded together) totally available and for sale $$$$$$$$$$ read about them in HOT ROD or some mag like that a few years back. i guess they are good enough at it you cant even tell where the weld is.

Aren't engine blocks cast iron? didn't know you could weld 2 engines together without thet weld breaking apart.

That V-12 posted above isn't welded together, if memory serves me right they were forged together, but what do I know

[72armyswbtruck]

Nope, the people he is talking about weld two aluminium blocks together
the make some serious power out of them too.

[Billla]

Very cool Check out this one - I've had some experience flying behind one of these and it's pretty amazing Before you ask, about $35K :-D

http://www.falconerengines.com/prod04.htm

[TP from Cntl PA]

Old OTR truck drives tell me that the V-12's were a true marvel to have under the hood..............If you could keep them running long enough to use the ponies. From what they said, the two separate engines combined was a bear to keep running correctly. They don't have the same following as the bigger V-6's alot of guys around here still speak about fondly.

[alf1096]

Originally Posted by Billla

Very cool Check out this one - I've had some experience flying behind one of these and it's pretty amazing Before you ask, about $35K :-D

http://www.falconerengines.com/prod04.htm

Its just MONEY

[QKENUF4U]

Originally Posted by 72armyswbtruck

Nope, the people he is talking about weld two aluminium blocks together
the make some serious power out of them too.

nope, these guys where using good ol cast iron blocks. they figured out how to weld them together (stainless steel rod from what ive been told/heard/read) and they would mimic the texture of the blocks on the weld and you couldnt tell. was a long time ago i read it so i cant give complete facts.
later
lance

[Canadian694x4]

That's a pretty sweet example...Wonder what they are asking for it??

[JAKES 68GMC]

I'd like to stuff that v12 in to a 32 Ford 3-window coupe.

[low'n slow]

I grew up in Nampa. That V-12 has been out there for almost 30 years. I think the manager told me they wire welded all the bolts to keep it from getting stripped.

[72armyswbtruck]

Yup, I know what you mean, my uncles owned a pot lot car lot near the Jalopy Jungle and we would always walk down to the yard and pic out the parts we needed for the cars.

[nu2-72]

Cast Iron stick rod is readily available and welds very nicely. I have welded manifolds, blocks, milling and drill vices and lots more. If it's metal, it can be welded.

[JAKES 68GMC]

There are welding rods to weld cast iron????

[LUV2XCLR8]

Luv to have it for my 2wd project and run "NO HOOD"

[Old Yeller 1970]

Awsome engine! I would leave to hear and see it run.

[Americanrider]

Originally Posted by nu2-72

Cast Iron stick rod is readily available and welds very nicely. I have welded manifolds, blocks, milling and drill vices and lots more. If it's metal, it can be welded.

Well... I think I can round up a couple of caddy 500's .... now where can I get a crankshaft that big?

[Brainchild]

Originally Posted by nu2-72

Cast Iron stick rod is readily available and welds very nicely. I have welded manifolds, blocks, milling and drill vices and lots more. If it's metal, it can be welded.

Yeah in fact you can pick it up at Oriellys here in town if you know what you're looking for because the jokers behind the counter can't find the a$$ with both hands and a map.

[Fred T]

HP ratings on these engines was misleading. Massive crankshaft kept the redline at 2,400 rpm. They were torque-monsters, no way around it. I drove trucks with the 478, but never the twin six. The 478 would pull like a mule, but you couldn't get in a hurry.

Here's a link for welding cast iron. It's not easy, but can be done with the right equipment.
http://www.twi.co.uk/j32k/protected/band_3/jk25.html

[smokekiki]

It is not that hard to weld cast.I would fill in for the guy that welded the ring gear to the cast turntable for the ladder on fire trucks.We used Ni rods.They where 99% nickel,and very expensive!The Ni rods are put down a bead that is machinable.It is very good for block/head repair,and is as strong or stronger than the base metal.
Very cool looking motor!

[wolfthing2000]

308 stainless I believe works also.