GMC Twin Six 702 V12

Doesn’t get much bigger than this

The GMC Twin Six 702 V12 has always been an engine that I have wanted to have in my engine corral. Although I am not exactly sure why I want it seeing how much it weighs 🙁

GMC V12 702
GMC V12 702

The GMC “Twin Six” 702 V12 is legendary to most who know of it, although it’s not really all that unusual. A V12 truck engine was not unheard of in the US and Europe, and the GMC’s 60 degree V6 certainly was not enough to power a larger truck. However the GMC Twin Six 702 V12 has acquired an outsized reputation as a cult object for certain hot-rodders rarodders and bloggers!

GMC Twin Six
Junk Yard Find

Now there are not many of these engines left as they fell out of favor so to speak. The block itself was the main piece needed to make this beast of an engine as the 4 cylinder heads along with the intakes and exhaust manifolds are the same as the big block V6 engines.

Twin Six Hot Rod
Home Made Hot Rod Twin Six powered
With 275 Horsepower at 2500 rpm and 630 Ft Lbs torque at 1600 rpm it is only somewhat impressive. However it’s noted for a 200,000 mile range without major maintenance is impressive. Especially with cars being spouted as to not needing major service these days until 100,000 miles.
Modern GMC V12
This engine was made to run on the lowest level octane too. So you choice would be either a GMC 6 cylinder diesel or this in a cab over in 1960 to 1965. With only around 5000 of these engines being built it makes then rather rare in their own right but, there is now a company that is using the original V12 blocks and updating them with a new top end believe it or not 😕

A few Rods have used this engine with one bunch being the somewhat famous Blastolene fabricators using it for this rather nice looking roadster rod 🙂
GMC powered Blastolene Roadster
GMC powered Blastolene Roadster

COE Twin Six V12 Rat Rod

Other Customs using GMC V12

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