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.