Quote:
Originally Posted by Blowd
While there is some debate on the Duke being a Chevy II motor or a Pontiac motor, The Pontiac received a cross flow head and became the corporate Tech 4 motor. This is the engine that became the "basis" for the Superduty 4 program. IMSA required basic components to be "interchangeable" with production pieces. There were a lot of variations on the Tech 4, but "R" engines and RWD seem to have the most in common. (don't quote me on the details).
The Superduty 4 parts are strictly race bread. I have one of the later blocks which had features such as: 5 [roller] cam bearings, 3/4" deck and main webs, semi siamesed cylinders, and deep head bolt bosses to name a few. The crank I have is 4130, fully counterweighted, [semi] knife edged, 3.625 stroke, with a Pontiac part number. No coincidence that John Callies was heading up Pontiac Performance at the time. Heads began with cast iron units that flowed 80% better than production counterparts, later developing into "433" and "801" (known by the last 3 digits of the GM part number)aluminum castings from Brodix. And finally the Coswoth DB head you see above. Brodix also made an aluminum SD block that was available through GM.
There are much better and more detailed resources available on this engine, but that's the Cliff Notes...
I'll try to get some photos of the block and crank up here later.
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If there was any doubt that the Iron Duke was a modernized nova 4 cyl based on the chevy 6 cylinder, all you have to do is go to the parts catalogue and check that many of the hard parts interchange with the early nova 4 cylinder and the chevy 6 starting with 1963. I would hardly call it a Pontiac engine any more than the 215 that resided in the 64-65 Tempests. More like a ressurected chevy design with a new crossflow cylinder head.
The whole reason they did this is because Pontiac didn't want to use the Vega all aluminum engine in their small cars (Astre Sunbird) because of the poor reliability and warranty problems associated with the Vega engine.
As history shows the Iron Duke had it's own share of problems when the blocks nickel content was dropped in the early eighties resulting in premature cylinder wear and the telltale piston slap and blowby issues associated with these engines. The Super Duty block however had much better material in it and more reinforcment that the standard passenger car block did.
Also the timing gears failed around 80-100,000 miles and were noisey long before they failed. And the vendor QC issues for whoever was making the connecting rods for GM that resulted in an approximated 25% failure rate of the deficient rods. The ventilated blocks were said to cause many of the resultant early model Fieros burn to the ground fire issues along with a smaller capacity oil pan (3.8 Qts.) in this car that allowed the engine to run out of oil more quickly than the warranty replacement 5 Qt. pans.
The Tech 4 derivative was supposed to address these problems and kinda did in the late 80s, although timing gear failure was still an issue. Probably a little known fact is that the 301 shared some parts with the Iron Duke too. Connecting rod and bearings and pistons bore sizes were shared. The pistons can't be interchanged due to the staggered valves in the Iron Duke head. Remember the 151 X 2 = 302 or close enough to 301. Pontiac did this in the early 60s with the 194 and the 389 too, to save some design and machining costs.