quote Originally posted by FieroWannaBe: I will have to keep that all in mind down the road, if I find the I6 balancer lacking.

Good Luck on your project. Seems like you are making good progress.

Not sure if you came across my build a few years ago (https://www.fiero.nl/forum/Forum2/HTML/133921.html) if not, here's the link. Maybe you can avoid a few of the mistakes I made. My SD4 is still running (knock on wood) but I get too much detonation / spark knock from 93 octane gas. I've had to start using a mix of 50% E85 and 50% regular gas to get high enough octane to get rid of the knock. I was able to tune for this, without too much problem. Only issue is that the E85 is not available near by and I have to travel a bit to get it. But still cheaper than trying to get racing fuel.

FYI, the EPA legal amount of an MMT octane booster (like Lucas) will give about 1 number octane boost. Lucas's recomended amount for "off-road use only" is about 5 times the legal amount and will give a 2-3 mumber boost. High amounts of MMT can create manganese deposits so buyer beware. I 'm planning a Quad 4 project with either boost or high compression and plan to dose 93 pump gas to 94 with MMT.

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

quote Originally posted by edfiero: Good Luck on your project. Seems like you are making good progress. Not sure if you came across my build a few years ago (https://www.fiero.nl/forum/Forum2/HTML/133921.html) if not, here's the link. Maybe you can avoid a few of the mistakes I made. My SD4 is still running (knock on wood) but I get too much detonation / spark knock from 93 octane gas. I've had to start using a mix of 50% E85 and 50% regular gas to get high enough octane to get rid of the knock. I was able to tune for this, without too much problem. Only issue is that the E85 is not available near by and I have to travel a bit to get it. But still cheaper than trying to get racing fuel.

I have seen your thread, Im sure some of the data point have played into my decision making, like just planning on custom pistons from the start. the big issue I am not over yet is figuring out what CC to finish the head at to bring my compression ratio to a usable level for 93 octane. I do have e85 available at 1 pump near me. But that's limits my range for travel a lot.
I have been exploring modifications to increase quench as well to make the pump gas more detonation resistant.

I just put my Iron SD4 head and the 2 barrel intake up on EBay.
https://www.ebay.com/itm/12...r=artemis&media=COPY

https://www.ebay.com/itm/12...r=artemis&media=COPY

The Iron EGR head is with it's new owner, and the 2 Barrel Intake is lost in UPS hell.

I did work on tearing the block down further.

I found a dirty little trick I am not too happy with:
A welding Main saddle, but it appears to be an adequate repair.



Unfortunately the builder of the engine decided to forgo the prescribed 1/2" main studs and Heli-coiled the block for 7/16 studs in all the holes to replace the 11mm threads the SD4 came machined with.

The OD of a 7/16-14 Helicoil should be 17/32, which is the drill size for a 1/2-13" Helicoil.
The problem is, I have to Helicoil if I want the use the "proper" 1/2in stud since the 7/16-14 Helicoil is larger than a 1/2-13" thread. I don't see there being enough meat in the block at the main bearing split for the 1/2"-13 Helicoil, which has an OD of 39/64".



I don't want a crack to develop if the hole intersects the notch for the bearing tangs.

I most likely need to keep the smaller main studs.

I have been on the hunt for a machine shop willing to work on my engine, which has been hard. If they will take on a 4 cylinder they dont have space, or they only do V8s.

I have a new to me cam shaft. Its a Mild solid roller from Bullet, 274/279 .570 Intake .590 exhuast, 242 @ .050 I 248 @ .050 E 106LSA

Finding solid lifters has been a challenge. Morel has a part number, 7774, but no dealers I call have them in their system.

I found some lunati springs on clearance PN 74744.
Per Bullets recommendation this should have over 600lb of load over the nose. Bullet has said the Rev Kit is old technology and is only used to add soring rate, modern sorings do not need the extra loads.

I do have brand new flat tappets if that is my only choice but my cam shaft needs a regrind to use as the lobes have surface rust.

I have been trying for the last 6 months to get a set of the Solid Rollers from Morel for the Iron Duke but have been hitting dead ends. Wafting on one shop to send me an invoice, but it's been slow. The Cam I bought off eBay, was custom ground by Bullet using a billet core. Interestingly enough, Bullet was adamant they never made it, nor anyone has ever made a roller cam for the Iron Duke, despite me telling him Dukes are Roller Cam from the factory 1986 and up. Once I gave him the serial number he found the data on the camshaft and admitted he made it. He went on to tell me No one makes roller lifters for this engine, I would need custom lifters form Crower. Crower gave me options; none would work with the correct length Tie bars. After pondering, and remember John Callies founded Morel Lifters, I found they make the correct lifters, but it's through distribution only. This has been my struggle finding a vendor willing to special order these lifters. I couldn't get anywhere with Lunati (Edelbrock Group) or Isky, if it wasn't catalog or in stock they just won't work with me, Howards gave me a price then stop answering my calls.

Bullet told me Rev Kits are outdated an unnecessary with modern springs. I am feeling like they are still may be necessary. His recommendation falls in line with the springs I pulled off my Iron Head (200lb seat, 600lb/in). I recall a talk from John Callies the Rev kit was necessary on the race cars, and they use Ford Flathead springs directly on the lifters to keep them on the lobes at high RPM. I can't find the source for that quote though to confirm. Isky discontinued the rev kit tools and parts. But with the instructions in my updated Build Guide I should be able to make something work.

[This message has been edited by FieroWannaBe (edited 04-29-2025).]

You are doing engine building on hardmode. IIRC there used to be a company, kansas racing products that made super duty blocks and cranks and they drilled them for chevy small block heads.Might be worth looking into to redrill the block for a small block head so you can get parts. You would need to custom make an intake adapter or cut up a small block intake but damn, probably easier than finding parts that don't exist.

You might be able to get ahold of someone who worked there and might have some parts or know race teams that used iron dukes... Heres the links I know about... https://www.yelp.com/biz/ka...ing-products-chapman

https://www.inliners.org/race/KRP/KRP.htm

https://www.speed-talk.com/...iewtopic.php?t=41460

[This message has been edited by Filben (edited 04-29-2025).]

Ask here. You never know who has stuff stashed away.
https://www.facebook.com/groups/1810116506182181/

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My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

quote Originally posted by Filben: You are doing engine building on hardmode. IIRC there used to be a company, kansas racing products that made super duty blocks and cranks and they drilled them for chevy small block heads.Might be worth looking into to redrill the block for a small block head so you can get parts. You would need to custom make an intake adapter or cut up a small block intake but damn, probably easier than finding parts that don't exist. You might be able to get ahold of someone who worked there and might have some parts or know race teams that used iron dukes... Heres the links I know about... https://www.yelp.com/biz/ka...ing-products-chapman https://www.inliners.org/race/KRP/KRP.htm https://www.speed-talk.com/...iewtopic.php?t=41460

None of those suggestions get me my solid rollers with the correct oil band dimensions and link bar spacing, redesigning the lifter bores for other lifters and head valve spacing is much more of a task than you're implying.

KRP is not operational anymore.

After machining and new pistons, I just need Roller Lifters, I am waiting on confirmation they are ordered and inbound from Morel, they DO offer a lifter set.

[This message has been edited by FieroWannaBe (edited 04-29-2025).]