A different DOHC Pontiac
 

Probably a majority of the posters here are into traditional V8 Power and drag racing, but I know there a few who like to carve a corner or use smaller power plants. I thought I would share my latest “find” with the board for the sake of novelty and its’ relative rarity.
Attached photos are the 16V DOHC head for the Super Duty 4 cyl program from the late 80’s. This was mfg by Cosworth for Pontiac (KK0555 for the top end kit). Pontiac rated this configuration at 375HP at 3.0L with a recommended shift point at 8250RPM.
While I really don’t have any current use for this, it is just such a rare item that I couldn’t pass it up. It’s basically NOS; the top end, block, crank, and assembly kit were purchased directly from GM but were never used, and sat in the owners shop for the last 10-15yrs (although the block, head, injectors, front cover, and dist were mocked up for display). I’ve got a LOT of small GM parts bags to go through still, but here are some photos of the “cool stuff” just for your entertainment and reference.
Post up if you if you want to see some additional photos or info. Hey, anyone have a set of Cams for one of these??:rolleyes:

I love weird stuff and Pontiac "historical" type things. Keep the pictures coming, please.

Eric

Cool Blowd - was that based on the Iron Duke- really the last true Pontiac engine .

Thank you for those cool pictures. That would look real good in my 63 Tempest or my 79 Safari.

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.

So then, if I am understanding correctly, this is a Pontiac head to fit the Oldsmobile "Quad 4" and not the Pontiac "iron duke" block?

Seen an "out-of-this-world" GM OHC 4CYL in the U-Pull-it ~Nov2008. Looked valuable. Should I go back to ID it?

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.

I believe it's a Cosworth head to fit the Iron duke block not the Quad 4. Cosworth also made heads to fit the Vega all aluminum engine around 75-77, which was also a 16 valve arrangement as this head is.

What he said^

In fact the Aluminum/steel 6 banger timing set makes an economical and more realible replacement for the Tech 4 fibre gear. But still noisy. I run straight cut steel gears OMG.

Will prolly turn out to be the aformentioned Quad 4, but certainly worth a peak. These things are pricey. Know of a guy who checked with Cosworth last year for just the Head Set. They believed to have 1 left, uncertain of completeness of kit, but initial quote was over $8K
I myself would trade mine for a basic IA2 shortblock....

The Cosworth Vega was "loosely" based on the Vega aluminum block, but there were some differences. It was also 2.0 lr. as opposed to 2.3. Sweet runner! MUCH tougher than the 2.3 counterpart. And while similar, the Quad-4 head doesn't have the open side. Quad-4 is a GREAT engine, with some "quirks".

In the early '90s, we built a fair number of the 2.7 lr. version of the 2.5 SD for "midget" racers. In one case, we dynoed one with 314 RWHP, gasoline, Hilborn injected. Those used the aluminum "cross-flow" SD head. GORGEOUS head!

The same 2.5 SDs dominated the "Goody's Dash" series for a number of years. In NASCAR "Mini-Stock", all "aftermarket" parts were banned. They still allowed lighter pistons and better rods, but ONLY "production" heads, blocks and cranks. They gave the 2.3 Ford a tremendous advantage by allowing the roller rockers, "turbo" head, etc. Still, we managed a few wins with the ol' Duke.

Today, we're in "parts collection" mode for an '86 Fiero we want to put a 3.4 Twin-cam in. That's another very well executed DOHC GM offering.

FWIW

Jim

The Midgets were right at 365 HP @ 7500 with our combo in 87. Mag SD block, 801 head and I think 2-1/8 injectors on methanol. Yes, you could twist it even more but making it through the season was more important. On the shorter tracks some of the old SD's are still running. There was one that finished 10th in 2002 at the Chili Bowl out of 200+ cars and it was using an iron block/801 head

I will say that it was not 166 CI and according to the owner they were only twisting it 7000. I do have a soft spot for them and always thought a stripper 3rd gen Firebird with about 200 CID SD and a Hair dryer would be a neat ride. I ran the what if's years ago and think it was good for 475 HP on gas and that was not leaning on it very hard.

In the day The Pontiac for midgets was a very reliable program compared to the Fontana and the Cosworth. The Pontiac spelled the end to the run by Autocraft VW's in Midgets. The Cosworth was only a few HP more and at 122 CID lacked the TQ of the SD. I can say I never have seen that head Cosworth) for the SD. It would have had to run at 122 CID and would have to have been much better than the 801 to make up for the 44 inches.

Just some thoughts from long ago and far away

Just did a Google search and according to Petersen's tech - the IRON DUKE 4 cyl . ( 77-93 ) is half a Pontiac 301 V8 - so there you go .

You've opened the proverbial can now:D
I'll start, Pontiac bore spacing = 4.62 Duke bore spacing = 4.25 (appr it's metric).
Did I mention there was some debate on this topic? :popcorn:
While the origins are really moot to me (except for parts interchange), as a Pontiac guy I've always referred to the Duke as a Poncho, but Sirrotica has already made the compelling argument on this. The 153 predates the 301 considerably and it's hard to argue when you look at 'em side by side.

I would figure it had the same bore spacing(4.4) as a SBC , nova 4, or chevy six? I have read the chevy 6 is the same as the SBC, and since the nova 4 and iron duke were based on this I figured it would be the same.

So for those who haven't messed with an SD4 block before here's a pic of the bottom end. Plenty of support, the pan rail is also thicker than production blocks. I mentioned 5 cam bearings before, it's more like 3 and 2 halves.
Crankshaft is pretty indestuctable by Pontiac standards. They originally shipped these with Chevy Bow Tie rods. You have to use a narrow rod bearing due to chamfer on both sides. There is also an oiling modification to oil the cylinders.
I'll get more pics of the Cosworth stuff and put 'em up for those who were interested.

Geez I'm busted, :o typed it into the calculator wrong (oh and I was looking at the lifter cover bolts not the cylinder C/L on my drawing). Yea more like 4.40 on the SD4, the Tech 4 actually had some shorter blocks for specific applications.
Why did I even bring this up..:doh:

Thats cool, no big deal.

This may have been answered already but, the Chevy II engines are different from the Iron Duke. The Chevy engine comes as a 3 7/8" bore[I believe] 153[super duke is 151, 4" bore] and in a marine version that is 3.0 litre or 181 CID[this is a later engine used in the 90's and maybe later]. These engines are not the same as the Pontiac 2.5 litre Iron Duke.

The bore and stroke is the same as a 301 but it is NOT half a 301 like the Tempest 194.5 was half a 389.