1984 SD4 Resurrection

[The Dark Side of Will]

If the SD4 is beyond repair, Ill probably get the car running with something available and attempt to sell it off.
If I can make the SD4 block useable for reasonable cost Ill go for it.

Ahh, that *IS* the SD4. My bad. As long as the bottom end is in decent shape, getting the block bored and getting new pistons should not be difficult.

Go with gapless top rings!

[FieroWanaBe1]

As long as the bottom end is in decent shape, getting the block bored and getting new pistons should not be difficult.

The Hot Rod Guide for the SD4 states the cylinder walls are thick enough for 4.020 bore without loss of integrity.
What they specifically mean by that I'm not sure. I wont know until I have it all torn apart and checked for wall thickness, I'm hoping it's salvageable, but I wont rule out installing sleeves on some of the cylinders.

I also have to take the head in to be disassembled. My valve spring compressor wont budge the springs on the current head.

[The Dark Side of Will]

If that's a 9000 RPM valvespring, you're going to have a hell of a time with that spring compressor.

[FieroWanaBe1]

https://a.co/d/7Ro7eL5
by next weekend I should have the '322 head disassembled after the proform compressor shows up.

I've been moving stuff around my garage, put my 86GT in a carport in my yard, and will work on pulling the engine out of the 84 and getting it disassembled and sent of for cleaning. Hopefully all that is done by fall. I Finally had a shop take my call on machining the '801 head for me.
I will attempt to reuse the valvetrain from the iron head on the aluminum one.

[FieroWanaBe1]

Valve spring compressor was a bust. the whole thing flexes like crazy and the triple valve springs wont budge. I'll have to use the hydraulic press at work, hopefully the cast pieces for the vice-grip style valve spring compressor doesn't fail under load.

Called a local shop https://www.amsracingengines.com/ about machining the '801 head, he said would try to fit in his schedule.

[FieroWanaBe1]

I got the head apart.
I 3d Printed some parts for use on the calibration SF-750 flowbench at work.
4.030 bore head adapter, valve pusher and indicator holder.
The ports on this head, Casting 10031322, has the EGR port cast in, with EGR holes in the center exhaust ports. The valves measure 2.020 Intake and 1.625 exhaust. all the exhaust ports have intrusions for the pushrod guide holes, the outside ports have casting bosses for the header flange bolt holes.
This head has been ported. It appears to be opened up a lot on the intake, but only for the first inch or so. The valve heads show a good amount of swirl in the carbon on the outside valves.
The intake ports on the outside have a large radius that blends the port around the pushrod guide, and the center ports have a more aggressive bend there. The floors are pretty flat, with a quick radius to the valve opening. I will cc the heads after I flow them, but I can tell, compared to my bare 10049801 head, the cross sectional area is much greater in the iron head.

[The Dark Side of Will]

Snazzy!

[FieroWanaBe1]

I have been playing with the options in my head:
If the 801 head after porting ends up with a lot better airflow, I could really benefit from more cubes.
Options are offset grind the 3.25 crankshaft to the honda journal 1.889 and end up with a 3.4" stroke, or buy up a 3.6" marine crank and have the ends machined for the SD4 block.
Looking at pictures, the marine crank is nice, but its not any SD4 crank, so would it really be the right pick for an 8000rpm engine?

[Shaun41178(2)]

If you're gonna spin it to 8k I'd use a real sd crank.

I always liked seeing SD buildups

[FieroWanaBe1]

I think I agree. the SD crank is probably the better choice, race proven above 4500RPM, unlike the marine crank, and most likely a fair bit lighter.
2.100 Pins offset ground to 1.889 (48mm), with a new stroke of 3.42 will yield 177 cu in, or 2.9L exactly.
Oliver lightweight 6.125 rods are available with the correct big end width and diameter, leaving a piston with 1.334 Compression height. It would have to be custom

A 6.2 rod would use a 1.261 CH piston and Hypers are available in flat top from Keith Black, but I'm not sure I would settle for Hypers. I also didn't find any rods outside of Carrillo, which are 70% more expensive than Oliver.

A flat top piston with a 65cc head will yield a 10.7:1 Compression ratio, which is in the ballpark of what I think I want for 93 octane.

[The Dark Side of Will]

Displacement is always king on the street.
Do you have pics of the marine crank? Marine engines are built tough and if it's fully counterweighted, it should be fine to spin up.

[FieroWanaBe1]

They show up for 200$ shipped on ebay, clearly need some journal cleaning.
Looking elsewhere I was eyeing some 6.200 long with 1.85 journal connecting rods on ebay for a song, with very lightweight pins. only $100 shipped, but are they still usable and straight? I can offset grind almost up to the 3.5" of the marine cranks on the SD4 crank and save a whole lot of weight.

[The Dark Side of Will]

Better view of the parting line? Is that forged or cast?
Fully counterweighted reduces stress on the main journals and keeps it from wiping the main bearings.
How much lighter are SD4 cranks? How much do the marine cranks weigh?

[FieroWanaBe1]

I'm going to try those Nascar rods, I will stick with the SD4 crank I have to find a shop that is willing to offset grind for a 47mm journal, I should be able to get up to the 3.5" stroke and be at 3.0L

Such a nice price, 102$ shipped, even if I have to rework them to straighten the bushings, I will be ahead of a new set.

My LQ1 rods, reconditioned because the shop said they were bent after installing the ARP bolts, were $80 a piece, plus the 65$ for ARP bolts, I was out $550, for stock PM rods.

We have 8 good used Pankl I-Beam Connecting Rods with Casidiam Coated Wrist Pins.

6.200" Long -1.975"(for the 1.850" rod journal size)-.903" Wide on the Big End
.700" Wide on the Wrist Pin End
Wrist Pin Size is close to .708"
.537 grams with 3/8" Rod Bolts

I don't have weights of the crankshaft right now, SD4 crank is still in the block until i make space to pull the short block from the car. And I haven't found any info on the marine crank weight, but the parting line looks cast, the last counterweight shows a fairly shallow line, SD4 parting line looks like a forging.

Marine crankshafts existed when the SD4 was introduced, OMC 3.0L 181 engines were released in 1978. Pontiac decided still to have a forging made for the racing engine program, It has radiused counterweights, and SBC width journals .940", the marine has 1.035" width journals.
These Nascar rods should play nice with my SD4 crank better once ground, Once I find a shop and send them my crank I can see what my stroke limit actually is, Maybe I can match the marine 3.6" or end up somewhere between 3.4".

All better than 3".

[Shaun41178(2)]

If the machine shop screws up the offset grind, they screw up a rare and expensive crank.

I wouldn't offset it for more cubes. Unless you can give them a trash crank to practice with first.

Remember Joe upson took his crank to have offset ground and it didn't turn out right.

[FieroWanaBe1]

I remember that thread.
It looks like there may be lots of blame to thrown around with that one.
If its not in writing and on a drawing, don't be surprised a machinist doesn't have telepathy.
At least in writing they have a weaker defense for the costly mistakes.
I'm not saying the machine shop did everything right, but there were some user preventable errors in that case.

[FieroWanaBe1]

Iron '322 traces over the '801 heads. Exhaust is raised and larger than the iron versions. The intake, as ported, is much larger in cross section than the '801, I will really be interested in the flow differences and efficiency as I port it.

[FieroWanaBe1]

Watching this video:
https://www.youtube.com/watch?v=T8OpKKwB2iM

The '437 aluminum head has lower intake ports with the same or near same port spacing as a factory head. The exhaust on the '437 appears to be the same between '801.
it does look like there is a lot of room to open up the roof of the exhaust on the iron heads, where as the porter of my iron SD$ head didn't go so far. Videographer says his is a 522 casting, it doesn't looks the same as my iron head a '322, less material. His head does appear to have more material to port than a Fiero head from photos.

[ericjon262]

are you still planning on ITB's? I bet a tri-y header would work well on one of these.

[FieroWanaBe1]

Just playing with some rods.