A bit of nostalgia this morning. If you have been around this business long enough you remember, and perhaps you even sold GMC trucks with 427's way back in the day.
Here is the deal:
Back in the day a GMC or Chevrolet truck with a 366, 5 speed, 9 front, 18,500 2 speed in the back, 10.00x20 tires and a 27,500 lbs GVW was the standard of the industry. These trucks sold by themselves, they had such a reputation of being the best.
At one point GM truns the 366 to a 427, as an aside this was not the same 427 as in cars, it had a tall deck block, and was used in trucks and marine applications. Although the 366 was bullet proof. The 427's were not lasting as long.
Numerous folks at GM were scratching their heads as to why a 366 would easily last over 200,000 kms in a truck and the 427 was barely lasting 100,000 kms.
Here is another deal:
Been in the business long enough you hopefully remember a company called McCallum that was transporting GM vehicles from the factory or rail heads to GM dealers in eastern Canada. McCallum had a numerous tractors with 427's pulling their trailers. Yes...they did not last very long the 427's.
GM in Canada enlisted McCallum to run various tests on various configurations of 427's. GM will install an engine in a McCallum truck, have the truck cover a speciifc mileage, take the engine out, replace it with another engine. Obvious do a meticulous tear down of the engine taken out of the truck. Yes...the old tachographs were helpful during the tear down.
The conclusion...not enough gas flow, the 427 required appreciably more gas than the 366. The by now iconic single 200 liter step tank with an electric fuel pump for the 366 created instances of fuel starvation with the 427. The solution...dual step tanks with dual fuel pumps.
In Canada, a 427, with a 5 and 4, 12 front, 38,000 in the back, with an Hendrickson suspension was the standard dump truck for countless years.
At the time GM had the medium duty truck market "locked up" with the 366 and 427.
The last deal:
Yes...the 427 were strong performers on the highway, very strong. Fuel economy...don't ask.