GMC V 12 702 CI in WI $3,200

[sagefinds]

A guy in Northern Colorado put one of the V-12 GMC's in a 35 GMC truck. He used to drive it to some of the get-togethers but I think it was more work than worth to maneuver it around.

[joe_padavano]

8 hours ago, rocketraider said:

Yes, domestic. Even with VIR right down the road we don't see many of the road going exotic engines, and I have become enough of a Philistine toward newer vehicles that I pay little attention to them.

OK, but the Ford and Dodge V10s were still made well into this decade.

[Stude Light]

What crazy designs those engineers came up with!

 

I had a lot of experience with the basic engine that this was designed from. In 1969, my father bought a new GMC KM2500 4x4 with the 305E 60 degree V6 engine. Bore was 4.25 in with a stroke of 3.58 in, it made 170 hp and 263 ft lbs of torque with a two barrel Stromberg carb with a manual choke. Not sure it was mentioned but the spark plugs are located on the carburetor side of the heads.

 

The engine was coupled to a Muncie SM465 four speed manual gearbox and a four shaft "Clover Leaf" Rockwell-Timken T221 transfer case with 4.56:1 final drives. Transmission ratios were:

First - 6.55:1
Second - 3.58:1
Third - 1.70:1
Fourth - 1.00:1
Reverse - 6.09:1

 

With a 1.96:1 transfer case low range it had a 58:1 speed reduction in first gear.......talk about a stump puller. We would drive that truck at 70mph on the highway and it just screamed with the transfer case gear setup. The truck got 11 mpg no matter how you drove it - fast, slow or trailering. With the 17 gallon tank behind the seat that didn't give you much range so you stopped often for fuel, especially when driving cross country.

 

The engine had plenty of torque but the acceleration was lackluster as accelerating to highway speeds was always a wide open throttle event. I seldom used 1st gear and never to launch with. With the high numeric final drive, the engine was always spinning lots of revs. I had to rebuild the water pump often and the Stromberg carb was a bit finnicky so it got rebuilt a few times over it's life. I did a valve job at about 140,000 miles and had to replace the transfer case coupler, main shaft and upper bearings around 180,000 miles. True to its advertising of 200,000 miles with no teardown, the engine spun a rod bearing at 226,000 miles and I eventually sold the truck in 1998. It lived it entire life in Michigan and was driven year round so the body had been reworked a few times due to the road salt used here.

 

My father purposely ordered this truck and engine for one reason.  After going to Colorado on an elk hunt, he was so impressed by the truck the guide used to climb up all the rutted up trails to get to the top of the mountain there were hunting on, he decided on getting the same truck and powertrain setup. Power steering and power brakes would have been nice though! A lower final drive numerical ratio would have also been nice but 4.56 was what the V6 engine came with. It was a basic work truck with rubber mats, manual windows, am radio, but did have a nice 8' wood bed that was always pristine due to a topper.

 

I have a lot of fond memories driving that truck and the engine was always a unique part of it. Anytime I went to the parts store and said I needed something for a 305E V6, I was always corrected by the young sales associate "You must have a 305 V8". My reply was generally "Open up the truck section and you'll learn something new today".

[joe_padavano]

13 hours ago, sagefinds said:

A guy in Northern Colorado put one of the V-12 GMC's in a 35 GMC truck. He used to drive it to some of the get-togethers but I think it was more work than worth to maneuver it around.

Nearly 1500 lbs and a 2400 RPM redline don't really make for an enjoyable drive.

[chistech]

I saw two of those V-12s sitting side by side in a couple of old cab over garbage trucks here in New Bedford MA. There was also a couple of early GM diesels in a couple other cab over garbage trucks. The company was a family owned business by the name of Frade’s and they kept those trucks until just recently when the company was sold. Both the gas and diesel engines were odd and i had never seen anything like them before.

[rocketraider]

1 hour ago, chistech said:

 Both the gas and diesel engines were odd and i had never seen anything like them before.

Diesels look like this? This is a 6-71 Detroit 2-cycle. Used in millions of buses, OTR trucks, construction equipment and anything else you can think of. 

 

 

What's that funny thing on the side of it?😃 One of my young friends calls that a "huffing device". Though on a Detroit all it did was move air and exhaust through the engine. No boost. That came later when the salt flats guys figured out you could stick a Detroit's Roots blower on a flathead and make horsepower.

 

And absolutely nothing else sounds like one. It just sounds dirty if you get my drift.

 

 

[8E45E]

I believe he is referring to the TOROFLOW diesel; TORO-FLOW - Diesel World (dieselworldmag.com)

 

It was used in a lot of those 'Old-Look GM transit buses.

 

Craig

[chistech]

2 hours ago, 8E45E said:

I believe he is referring to the TOROFLOW diesel; TORO-FLOW - Diesel World (dieselworldmag.com)

 

It was used in a lot of those 'Old-Look GM transit buses.

 

Craig

I believe you’re correct. They were definitely “V” configuration and i also believe they were 6’s.

[Dandy Dave]

Years ago, when I worked at Catamount Ski Area, we had a bank of Ingersoll- Rand screw type air compressors 750-1900 CFM. Most were powered with Detroit V6-71's. The 1900 CFM had a V8-71. Guaranteed they would suck a gallon of oil in 24 hours while making snow. These ran between 1,900 and 2,100 RPM depending on how many snow guns were running at the time. The sound that bus makes is very familiar to my old ears. One of the 1400 CFM compressors had a Cummings. That used maybe a quart of oil in 24 hours if that. When the Detroit's were getting tired, they would go though 3 Gallons in 24 Hours. That meant it was time for a replace and rebuild.   

[Mike "Hubbie" Stearns]

If the old Detroit’s didn’t use or leak oil, they are blown up. Mike

[rocketraider]

The kid who calls the blower "huffing device" also says every Detroit he's ever heard sounds to him like it's about to blow up.

 

But I like the sound they make, especially that "mutter" at idle. Sounds like a by god Diesel as they were meant to sound! Cluck-luck-luck-luck...

 

[junkyardjeff]

I remember the first GMC V12 I seen was in a junkyard in a semi,did not know they were made so I opened the hood and seen what I thought was a V6 but looked further back and seen the rest of it.