Pontiac SD4 801 Head and Valvetrain Parts

[StandUpToFight]

I am in the slow process of rebuilding and refreshing a Pontiac "151" SD4 build. The original motor was a street motor in an 84 Fiero, and the block and head were purchased in 1985 from Pontiac.
10027633 Super Duty 2.5 Block
10027779 3.25" Stroke Super Duty Crankshaft
10031323-Cast-Iron head with EGR
I picked the Car up in 2015 and have been ever so slowly taking the engine apart.
I bought a Aluminum head off Ebay in 2015 shortly after buying the Fiero, Pontiac PN 10049801 — Super Duty Four High Port Special Aluminum Cylinder
Head

This version of Pontiac’s Super Duty four-cylinder aluminum cylinder head's
are designed for maximum-effort competition engines. The intake runners
and water jackets are raised .670" to improve flow. In the Special High Port
casting, the two center intake ports are moved .800" closer together to
straighten the path to the valves. Both heads’ rocker cover rails are raised
.300", and the exhaust ports are raised .600". The valve centerlines are
relocated to unshroud the valves, and the rocker stud holes are moved to
match the new valve locations. The valve seats will accept 1.94–2.08" intake
valves and 1.60–1.625" exhausts. The combustion chamber volume is 67cc.
Technical Notes: Valve guides are supplied but not installed. A template is
provided for redrilling headers to fit the revised exhaust flange bolt pattern.
An intake manifold must be fabricated to fit the High Port Special's port
spacing.

I don't really care to run the Iron head, its heavier, has EGR ports that I don't care for, and didn't flow what I expected when I tested it, I'm a little young to have been around these motors when they were being used in racing, and no one I know has messed with 4 cylinders. So I'm just reading internet information, and magazine info that I have found. I have the Build Guide Pontiac Published when they released the motor.
I have only seen a photo of one of these heads fully assembled, and it had Jesel shaft mounts on it.

My block is the 3 journal bearing cam block, it appears from what I see Pontiac went to a 5 bearing cam block with rollers bearings later in their production. The engine right now has a hydraulic flat tappet cam, but I've got some rust on the lobes, and have no clue the specs. I see Isky still lists several cams for these engines in their catalog, so I think will run their one of their hyd cams. I will street drive the car, autocross it, and track it at Road Amerrica or Autobhan, I think a circle track spec cam would work well for that.

I had emailed Jesel in 2015 about a shaft rocker system and was told KPS-02716 is their pro series for this head.
What I am wondering, if anyone is familiar, because the valves and stud holes are relocated on this head, will I need offset lifters to run this head with my block?
Am I locked into a Jesel Pro rocker system, or like other 151 Pontiac heads, can 1.7 or 1.8 BBC roller rocker work with this head?
I placed my iron head (322 casting) studs and guide plates on the head this morning, and the 801 heads pushrod holes were about 3/8" further away from the stud that the guides were, which makes me wonder if this head was designed around a different rocker arm. ISKY does list their larger Roller cams with a 1.55:1 ratio.
Does anyone have experience with this head or motor? I have yet to see anyone make one of these heads work on a street motor.

[Racer71]

My brother has one in a midget, they used to be popular in the mid 80’s in the midget world. It came in a older car he bought to run indoors some. I guy we race with used to build and run some and said they made pretty fair power at the time. I haven’t had this one apart, we’ve been discussing going through it as we’ve never heard it run, that way we would be able to tell someone what’s in it parts wise if he decides to sell it. I know it has jesel shaft mounts on it as the valve cover was just laying on it and the push rods weren’t in it so the none of the springs were compressed during storage

[StandUpToFight]

Did some test fitting.
Rocker studs, even shortened per the SD4 build guide spec are threaded too long to fully seat. Also the pushrods for the low port head are way too short. Makes sense Pontiac said the rocker cover rails were raised .3", and the stud holes are flush with that.
It looks like the BBC 1.7 rockers will probably not work, the distance from the pushrod to the cup appears to be too short and they dont cover the guide holes completely. Attached are some photos that kind of illustrate the issues.

[dirtrokker4]

If you aren't interested in selling the iron SD4 head, let me know. I am building a Pontiac 4 for in my T Bucket and would like a decent street head. Thanks and good luck with the build!

[StandUpToFight]

Once I figure out how i can get the high port head assembled and running I would be fine selling the iron head and intake setup.

I just got an email back from Brodix, who made the head for Pontiac, they had given up all proprietary information when Pontiac was shut down. So no information from them on valvetrain dimensions. They suggested 3d scanning an assembled head.

[mag2555]

My 1985 special edition of Hot rod magazines coverage of the SD4 motor has these pictures of Crower stud mounted rockers on the Aluminum SD head.

It’s said that the studs where from Dimond racing.

The picture I put up here of the head itself is the SD iron head.

[StandUpToFight]

Id love to see more of that edition. What does the cover of that look like?
I bought several magazines I could find detailing the SD4.
My hot rod special on the SD4 was from 1983 And only details a very early iron head, and it is the same as a digital copy I got off a Fiero website a decade ago.
I have copies of some other articles that discuss the high port head, but they all detail the Jesel shaft rockers in 1.55 ratios.

If the rocker rails are raised along with the rocker stud mounts .300 over other SD4 heads, im assuming my valve tip should move .300 higher as well if I am to maintain decent rocker geometry.

[StandUpToFight]

The only blurb with information about the high port head outside of Pontiac Catalogs

Looking closely the 437 aluminum head has taller rocker stud mounting than the cover rails.
Maybe I was wrong about valve length.

[StandUpToFight]

If the BBC rocker is 1.650 in arm length from the fulcrum to roller center, I am thinking the best fit rocker arm is a set of these .050 backset BBC rockers. They should put the rocker stud to be 1.600 away from tip center line And if I can still get the ISKY Cam PN 951292 (292 Mega grind) I would prefer to use the 1.8 ratio rockers, Crower PN 73685-8.

My old camshaft is a Lunati SP295-522 , I don't have any details on that cam other than it has a 106 LCA, but I would like to target at around .600 lift to take advantage of some head flow.
My Iron head peaks at .6 lift at 248CFM with a 180cc port. I really would like to be above 275CFM on a similar port volume with this high port head.

[StandUpToFight]

Here is the flow chart for the iron head.
I'm really hoping to approach 275CFM with the raised port head, the pinch is gone for the pushrod, and the short side has a radius, not just a short waterfall.
I ran this on a SF750, 4.03 bore adapter, with a radius on the inlet as well as the 2BBL intake, and a formed pipe on the exhaust.

iron head w intake.jpg

[StandUpToFight]

After reviewing all the documentation I could get my eyes on regarding this head.
It sounds like Pontiac development was:

• 10027776/10027775 1st Run Iron head, with Production based exhaust runner shape, and large pushrod holes and head bolt holes must be sleeved after porting)

• 10031322/10031323 Redesigned Iron head with raised floor exhaust ports and reshaped intake runners that do not require sleeves to be ported fully.

• 10038433 is 1st design of the aluminum head, has the same exhaust port design as the iron, with a revised cooling jacket, and guide/seat inserts.

• 10045437 is the 2nd design of the aluminum head, this head has raised and enlarged exhaust ports and raised intake ports.

• 10049801 is the 3rd and final design of the aluminum head this head has raised and shifted center intake ports, and the same large exhaust ports as the 437 head.

I have the 801 head, it looks like the stud mounted rockers are an option, and I have since found several Fiero people running with the 437 head using studs mounts with this head, and there appears to be no geometry issues, although My block is an earlier block (2.5SD -vs- Super Duty), I may need to clearance the deck.

I did notice some difference with the 437 heads vs my 801 head, Not sure if its casting changes or changes done by the specific porters/Builders.

s-l1600 (15).jpg

This 437 head has a hear shaped chamber, I would think it has been welded up to ported to final shape, but maybe Pontiac had a test casting made?
There are also channels for the oil drain back, I have seen these on one other 437 head, but it isn't present on others.

image000000_(3).jpg

This 437 head has "standard" SD casting chambers, but is missing some coolant ports to the block.

IMG_20200127_144617.jpg

This 433 head matches my 801 head on the bottom.

s-l1600 (1).jpg

This 437 head has the channel in it for oil drain back

Screenshot 2022-10-01 091838 - 437 al head ex.jpg

These 437 heads also matches my 801 head on the bottom side.

The aluminum heads all have the intake valve coolant passaged blocked off, as recommended as a modification to the blocks on early SD motors.

20210424_144834.jpg

Has anyone seen any other casting variations similar to the differences I am seeing, The oil drain back channel makes sense, especially for engine lacking external head drains, I may grind that into my 801 head, since it has no channels present.
Is welding and grinding more quench pad worth it?

[jsgarage]

Huffacker Engineering did some work on the 4 cyl SD during GM's attempt at the under-2 liter class in road racing. Unfortunately, one of my friends that got one of the 3 or 4 tube framed SD Fieros only kept the body/frame/suspension.

[Pontiac3.3l]

I'm interested in the 323 cylinder head if you have gotten the 801 figured out

[mag2555]

Your posted intake flow numbers for a throat size of 1.8” are not good.

Also the flow regression seen taking place starting at .600” lift is a sign that the short turn does not have the needed overall arc to complement that 1.8” throat.

Depending on the heads overall short turn height this may need to be addressed with a rework of both the short turn and the bottom cut around the short turn.

[Flybeau]

Wow what a great thread. Very informative and great research !! I have a mini rat rod s10 square body project. Worn out iron Duke. I figure rebuild it and turbo maybe - then I stumbled upon the sd4 two days ago and I’m a sponge now. Lol. Thank you all for sharing a wealth of specs and information for the noobs like me. Grin. And with that … ad me to that list of guys that would like the other head when you get read to part with it.
Thanks
Beauregard