Thursday, February 22, 2018

What's the difference between a 428, a 428 Cobra Jet and a 428 SCJ? Or the 429, 429 cj

The CJ block differs from the plain 428 due to the additional webs cast into the main bearing saddles. 

The SCJ block is the same as a CJ, and to that they added 427 "LeMans" connecting rods, better intake manifold, and an oil cooler, plus crank, rods, pistons, wrist pins, flywheel/flexplate

The 428SCJ was externally balanced with a counter weight behind a different harmonic balancer and an electronically balanced crank shaft  on the 428CJ

If you believed the ads, you had to wonder how Ford sold any Cobra Jet and Super Cobra Jet engines at all. Compared to a plain ol' Thunder Jet 429, a Super Cobra Jet would cost about $500 more and net you 15 advertised horsepower.


You could get that from a set of headers and a better cam, then buy a set of sticky tires with the change.

For a 429 comparison

The standard 429, with two-bolt mains, 2.09/1.65 valves, 10.5:1 compression and a 600 CFM Autolite on top, was rated at 360hp @ 4,600, and a gut-busting 480-lbs.ft. of torque at 2,800 RPM.

Let us assume this is a real number, and use it as a baseline.

If you'd b ought a Torino, for an extra $356, you could step into a Cobra Jet.
You got a 700 CFM Rochester carb, slightly smaller combustion chambers and 2.24/1.72 valves in the heads, a compression bump to 11.3:1, and stronger main-bearing webbing.

Ford advertised it with a mere 10hp gain and a net loss of torque--370hp @ 5,400 RPM, and 450-lbs.ft. (30-lbs.ft. less!) at 3,400 RPM.

From there the step up to the Super Cobra Jet package in a Torino meant the 3.91 ($155) or 4.30 ($206) axle ratio.
The CJ's two-bolt mains give way to four-bolt mains, the pistons are forged aluminum instead of cast, a 780 CFM Holley carb sits atop a bespoke intake manifold, there's an oil cooler hanging off the front of the radiator support, and a nasty solid-lifter cam requiring manual adjustment.

That's a lot of upgrading just to satisfy an axle ratio. There were also some external tells: a single incoming fuel line versus the standard CJ's twin lines, a slightly different air cleaner. The result? A rated five horsepower at 200 more revs. Five. The torque numbers remained the same.

Funnier still, a cold-air intake was optional on both engines, and (if the paperwork is to be believed) proffered no power gain. None. If a solid-lifter cam and extra air from multiple sources isn't enough to get more than five horses out of an engine, Ford's engineers should all have been fired on the spot. If the standard CJ was a 400hp machine, we'd peg the SCJ at around 425 to 430.

a 460 crank in an SCJ will get you 11.8:1 compression and 500 flywheel horsepower with few other changes


  1. Like the Chevy L-88 was 5 hp less than the trip set up Corvettes, because they lied their ass off to keep people from buying the L-88 who didn't know what they were getting into.

  2. the 429 Thunderjet was an amazing engine,
    in 1981 when I was 16 I bought a 69 4 door Thunderbird for $500

    and OMG, that was the most powerful engine ever,
    it would burn the tires until it shifted into third gear.
    you could be driving 15 mph and just floor it, and it would break the tires loose, you certainally didnt have to powerbreak it to spin the tires like every other car.

    my father had a 74 caprice with a 454 and the Tbird was far faster than the 454