Help with GMC Big Block V6

[SirNik84]

My dad has a 401 V6 in his 61 dump truck. He just called looking for the timing and dwell spec on this engine. I'm pretty good at finding random bits of data like this for my dad... thanks to you forum guys normally... So I thought I'd ask if anyone has any experience with these engines? I can't seem to find the answer anywhere.

[TheDon]

ooo HDR

[Eskimo]

I have no personal knowledge of this, and can't vouch for the accuracy of the information - but have a look at this page.

The site appears to focus on the GMC V6 engines.

[SirNik84]

excellent! that site had the info i needed. Thanks!

[catmandoo62]

cabover.watch those torsionbars,they tend to break then those cabs are hell to lift.back in the early 60's they took 2 of those and joined em and made v12 engines.weren't many made but they are out there.http://www.thunderv12.com/

[SirNik84]

I've read about the V12s before, weren't they in small trucks used to maneuver B52s? I love the look of those engines. My dad has another GMC dump truck a 55 that is engine-less. He told me he ehter wants to find something rare like the v12 to install in it, or a diesel. I think a Cummins would fit nicely in it.

[Honus]

I've never heard of a 400 CI V-6. It's probably a torquey son of a gun.

[rscurtis]

They made them up to 478 CI. It was the real deal, designed as a truck engine. On the other end of the spectrum, GMC also offered a 305 V6 in their pickups. It was the same physical size as the 478, so swaps were possible. I once saw a Texaco fuel tanker with the V 12, complete with its 4 mufflers.

This same engine saw life as their Toro-Flow diesel, but it was not a successful adaptation.

During the fuel crises of the 1970's, most of these big gas jobs went to the scrapper.

[Eskimo]

On the web site to which I linked in an earlier post, there are some interesting pictures to see. One of them shows some of the literature about kits to "repower" non-GMC vehicles.

I remember Dad telling me a story about how, back in the day, someone at their wholesale beverage business had been talked into buying a new Ford delivery truck - against the recommendation of the indy mechanic who usually took care of their vehicles.

The Ford engine turned out to be a disaster. After much misery, the indy mechanic suggested that GMC made a good V6 truck engine, and that a kit was available to put one into the troublesome Ford - which is exactly what they had him do, with good results.

According to Dad, it used to take some of the gas station guys by surprise.

[panZZer]

Originally Posted by rscurtis

They made them up to 478 CI. It was the real deal, designed as a truck engine. On the other end of the spectrum, GMC also offered a 305 V6 in their pickups. It was the same physical size as the 478, so swaps were possible. I once saw a Texaco fuel tanker with the V 12, complete with its 4 mufflers.

This same engine saw life as their Toro-Flow diesel, but it was not a successful adaptation.

During the fuel crises of the 1970's, most of these big gas jobs went to the scrapper.

Im the resident old GMC nut, I have never heard of this toro flow diesel not supprisingly, i didn't really know much about 305-478 v6's or the "twin6". I know more about 270's and the 302 straight 6's everyone who messes with old straights wants a 302 because they are 150 hp compared to 96. They cost an arm and a leg to rebuild, theres a 302 govy rebuilt yrs ago one on c-list now for $400. type in army truck into search tempest, I think in nebraska.

[Air&Road]

My Dad had a two ton flat bed in the early sixties with this engine. The guys in the shop used it to haul Fork trucks. I can remember the guys talking about how well it would pull the hills as compared to the early fifties International that it replaced.

IIRC, the downside to this design, albeit an obscure and rarely encountered issue, was that it had heads and block similar to the 348/409 which required a back cut when boring. There was no combustion chamber in the head, rather the block deck was at an angle. The back cut had to be made with a boring bore to allow a ring compressor to fit in place during assembly. Not a big deal, but was an idiosynchrocy of the breed.

Larry

[rscurtis]

The Toro Flow's achilles heel was the fuel injection pump that was used on it. Apparently, its timing control was not that good, resulting in head gasket failures. Many TF owners removed the diesel and replaced it with the gas version just to maintain an operable truck.