1960s-Era GMC 5.0 Liter Was The First V6 Engine In Pickup Trucks: History Alley
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While all truck-related attention today is on General Motors’ launch of the all-new 2014 Silverado and 2014 Sierra, let’s take a trip down memory lane and pay the 1960s a visit — when GMC, then an individually-functioning division (rather than a brand) of General Motors, debuted the first V6 pickup engine in history, and one of the very first V6 powerplants produced by an American company.
The unique 60-degree six-banger, offered exclusively by GMC through most of the ’60s, started at a displacement of 5 liters and made 220 lb.-ft. of torque and 120 horsepower… compared to the 305 lb.-ft. and 285 horsepower, and undoubtedly much higher fuel economy, produced by the new 4.3 EcoTec3 V6.
GMC’s 1960s-era 5.0 V6 featured aluminum pistons for improved cooling as well as a stout crankshaft and bearings designed for superior durability. The engine was available in various sizes of displacement, including 5.8L (354 cubic inch), 6.6L (403 cubic inch) and 7.8L (476 cubic inch) versions, later spawning a 7.1L (433 cubic inch) variant with enlarged crankshaft journals and a 10.4L (635 cubic inch) 60-degree V8 with twin balance shafts using the same general architecture as the 305. There even was a monstrous 11.5L (702 cubic inch) “Twin Six” V12 which was basically two 5.8s placed end-to-end with a common block and crank. A diesel-burning version was called the ToroFlow.
“The family of V-6 engines introduced in 1960 was designed to last, and I’ve heard of some owners going more than 450,000 miles on the original engine,” said GMC truck historian Donald Meyer. “They had really high torque and pulled loads well. GMC engineers know how to build durable, reliable engines that never quit.”
Sounds a lot like the new (and oh-so-torquey) base 4.3L EcoTec3 V6 engine in the 2014 Silverado and Sierra, doesn’t it?
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I really want that Twin-Six
I wish I had a dollar for every 305 V6 I changed oil in.
I also loved the warranty engines. GMC used they put plaid valve covers on them. Today collectors highly prize them.
We get customers with the 12’s today as they love to get these and but them in street rods. Not fast but they may a good reliable and cool looking engine.
Now if GM could have adopted this smoother 60 degree design for use in the 70’s fuel crunch years instead of bringing Buick’s rude crude uneven firing 231 V6 think how many more happy customers they would have had up to the throughout the years.
Were these engines used in their light duty vehicles or just medium & heavy duty?
I’ve never heard of this engine line.
I thought GMC just used Chevy engines.
In the 50’s they also used Pontiac & Oldsmobile V8s.
GMC advertises “Professional Grade” and they are just rebadged Chevrolets but 50-60 years ago they actually were professional grade compared to Chevrolet.
“when GMC, then an individually-functioning division (rather than a brand) of General Motors, debuted the first V6 pickup engine in history, and one of the very first V6 powerplants produced by an American company.”
GM should go back to running all their brand as almost individual companies
That would be nice, if GM could afford that again.
We now have less innovation and individuality between brands.
ben saying this for years auto makers are being lazy
Nothing to do with “lazyness”. I too appreciated the individuality or the various GM divisions but the world around GM was changing.
The biggest problem with the individuality (engine wise) between brands was the cost once government got involved. The EPA certification process was the death knell for the individual engines. Each particular engine/transmission/axle ratio combination withing weight classes 500 pounds apart made individual engines between divisions a very expensive process (too expensive).
And as far as the big GMC V6 goes, it was an overbuilt engine for pickup trucks. In 1964, GMC introduced a cost reduced model with the Chevy inline 6. I’m sure it was a result of the price being uncompetitive with other similar 6 cylinder pickups on the market because of the greater production cost of the heavy duty V6. By the late 60’s, you couldn’t get the V6 in a pickup anymore. And eventually the V6’s went away in the big trucks too, replaced by Chevrolet engines. (cheaper to produce and easier on fuel)
The 1973 oil embargo also helped the V6’s to disappear. And to my previous point, the EPA was setting sights on bigger trucks by then too. The surface to volume ratio of the short stroke V6’s was the reason they used more fuel than other similar sized engines and made them dirtier as far as carbon monoxide and unburned hydrocarbons were concerned. International designed the MV series of V8’s to replace the small V engines because of emissions and Ford phased out the FT engines and replaced them with 385 series V8’s for the same reason.
Make that “oil embargo hoax”. Also, that v-6 was definitely common in their pick-ups.
You forgot to point out that CAFE requirements have practically ended any new engine development in this country,.
It wasn’t just that those V-6 es used more fuel. They had a tendency to inhale prodigous amounts of oil as well. Large pistons allow more oil to drift up from the crankcase. But they were definitely overbuilt, and they had a host of other issues as well. They could pull a tank, but they offered no performance in the way of speed, which was deadly in the performance happy 60s. In the larger trucks you would only be doing 35mph by the time you hit 10th gear. That led to folks over revving them on the highway, which then led to many early rebuilds. It isn’t hard to understand why these engines disappeared. Now if they had shown up in 1950 …………………
Do you have any more pics of the truck that you showed the fender emblem above on? Its a concept design that never made production
I believe that was one that someone had custom made. The GMC trucks did not have the option of the double chrome lines on the custom cabs. Those were on Chevy Trucks only, the GMC offered a single chrome strip down the side of the body and this came with a chrome V-6 logo for the hood instead of the standard painted one.
I, too, am intrigued by the fender emblem. It definitely looks like a prototype GMC factory emblem. Does anyone know where this photo came from? I’d love to see some concept photos of the 60-66 GM trucks.
I have a 62 GMC fleetside with the 305 V6. Runs great looking to change it out with a V8 during some restorations. Is the old motor worth anything??? Thanks
you are an idiot
Actually the writer has some of the displacements wrong. The other sizes besides the 305 were 351, 401 and 478. Later, the 478 crank was used in the 351 to produce a 379 and the 401 with the 478 crank was a 432. There were diesel versions of the 351 and 478 as well as the V8 version of this engine at 637 cubic inches. The 637 replaced the V12 in 1966.
These were a way overbuilt and designed engine that is probably the most heavy duty gasoline engine ever produced. I am fortunate enough to have collected a few and owned several more over the years.
You cannot compare the 305 V6 to the new 4.3L ecoboost. The former would out pull later like there is no tomorrow. The 305 had power right from idle just no RPM!