|Pontiac's 389 & 421|
1955, Pontiac introduced its new Strato Streak V8, which
displaced 267 cubic inches. This block is the basis for approximately 17
different engine displacements ranging up to 455 cubic inches. Hot
rodders liked this feature because virtually all the engines were
interchangeable without modifications. The engine grew to 370 cubic
inches by 1958, and for 1959 Pontiac unleashed the legendary 389.
It was called the Tempest 420E engine in the Pontiac shrowroom brochure. (sample page below) Little mention of the engine was made and certainly no pictures were presented, probably due to the AMA racing ban. God forbid we should see what the engine looked like. What stupidity. At any rate, the 389 was available for 1959 with a top horsepower rating of 315 with tri power and 10.5 pistons. Over the years, the 389 would be available with a dizzying array of horsepower ratings, with up to 363 advertised for the 1961 389 Super Duty race engine. The factory tri power 389 was rated at 345 hp, so you can bet the SD was putting out a lot more than they were admitting to. Yeah, you could order one, dealer installed. These were good for 14.1 @ 100 in the quarter mile in a 1961 Ventura coupe.
1962, Pontiac officially introduced the 421 Super Duty, a
killer Nascar engine sporting 2 four barrels, 11.0 pistons, and 405
horsepower at 5600 rpm. Ahem. Okay, we believe you. Hand built in a
special factory tool room, the first Super Duty 421s debuted late in 1961
as race only engines. Pontiac was vague on their output, but estimates
ranged from 373 to 405 bhp. These were the largest displacement
engines offered at the time, and they helped spark Detroit's cubic
NHRA rules changes for 1962 required engines and body parts for the stock classes to be production pieces. This forced the 421 onto the official equipment sheet as an expensive, limited run option. Fewer than 180 were built for 1962, its peak production year. Most went into Catalinas, though 16 or so were installed in Pontiac's new personal luxury coupe, the Grand Prix.
The '62 Super
Duty 421 was officially rated at 405 bhp,
but actual output was closer to 460. Though street legal, these
again were race ready engines with four bolt mains, forged rods and crank,
solid lifters, and NASCAR heads. Stock car racing versions used a single
four barrel, but street/strip Super Duty 421s had twin Carter 500 cfm four
barrels and an aluminum intake manifold. They easily turned 13.9 @ 107 in
street trim, getting from 0-60 in 5.4 seconds.
poured on so much performance
that only an order from the highest power could slow it down.
Unfortunately, that's what happened with the Super Duty Project. Super
Duty 421s were back, tougher than ever. Compression jumped from 11.0:1 to
12.0:1, while other tweaks increased maximum shift points by 500 rpm to a
screaming 6400 rpm. The four barrel version, set up for sustained high
speeds, had 390 hp. The dual quad drag variant, now with aluminum exhaust
manifolds standard and steel manifolds optional, was again underrated at
405 hp. A second dual quad drag rendition was introduced with a 13.0:1
weight cutting again included aluminum front end pieces
and included by the famous Swiss Cheese frames, which had grapefruit
sized holes drilled into the chassis rails.
Super Duty 421s again
came only with a
those unwilling to take the Super Duty plunge,
The 389 and 421 engines were continued through 1966. In 1967 Pontiac replaced the 389 with the 400. The 421 became the 428, with a top street rating of 376 horsepower. Quite a few of these still potent engines found their way into GTO engine bays. Cheater!!!! Who, me? Never. It's a 389. I swear. All in all, the 389-421 combination sold a lot of cars for Pontiac, and won a lot of races. They were always very competitive against MoPars, and are very collectable today.