Project: Iron block 5.6

[Tony H]

So I have given the head gaskets much thought. Initially I was going to use 560 head gaskets and port them to correct a few mismatches in the cooling passages. The bore centers and locating dowels were spot on. But then they are thinner and designed for head/block of the same material. So I'm thinking about having the 4.5 gaskets modified for the larger bore but I can't find anyone that can do it. Custom head gaskets are $$$ for 1 set. They would need the bores enlarged and fire rings.

[rwd4evr]

Have you looked at the early alloy 5.0 117.960? They are more of an alloy version or the iron block than thier own beast like the rest or them. The gaskets may be different too.

[Tony H]

I have not but the alu block has slightly different coolant passages. I think I want the thicker iron block gaskets. I might call my machine shop in Portland and see if they have any ideas. I want as few areas for problems as possible.

[rwd4evr]

Yeah I don't know too much about them or if they're even readily available. I just know that they are considerably different than the later alloy 5.0. the early 5.0 from the 450slc 5.0 is what I'm talking about. They may still have the same style water jackets as the iron block. They still have the large ring gear and separate adapter plate on the back of the block. I'd at least look into it. If you can get MLS gaskets made that's the way to go.

[Tony H]

I can get custom MLS gaskets made but for 1 pair they are at least $350. Considering the cost of the project it's not unreasonable. I may go that route.

[rwd4evr]

Can't hurt to look at the 450slc 5.0 gaskets. 78-79 I think is it. First like 1246 or something like that I think. Fonzi can tell you that for sure. I've got one here but it's all together.

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[mercmad6.3]

I had to rebuild a customers m130 280 last Christmas (!) and the oversize head gaskets are NLA. (!!) so i got a firm in Sydney NSW to make one which cost $150 AUD . Which is less than 1/2 the price of a new one used to cost from Mercedes. If you can't get gaskets made,get someone who does laser cutting to make you a pair from sheet copper (around 3mm thick ) .On my race hemi engine I used copper gaskets because of the 13-1 compression. Everytime the heads had to come off it was simple matter to heat the gasket a dull red and quench it in cold water. This softens copper.

Originally Posted by Tony H

So I have given the head gaskets much thought. Initially I was going to use 560 head gaskets and port them to correct a few mismatches in the cooling passages. The bore centers and locating dowels were spot on. But then they are thinner and designed for head/block of the same material. So I'm thinking about having the 4.5 gaskets modified for the larger bore but I can't find anyone that can do it. Custom head gaskets are $$$ for 1 set. They would need the bores enlarged and fire rings.

[RobertinMN]

So--where is this project? I joined just to ask this question, Mr. Tony. I have, at the moment, a 4.5L engine torn down, 4.5 heads already done before discovering the cylinder walls may need more than just a honing and standard pistons and rings put it.

I am considering, right now, going down your path.

[rwd4evr]

He's progressing along.do you have a k-jet or d jet engine? I may have one to.sell if it comes to that.

Originally Posted by RobertinMN

So--where is this project? I joined just to ask this question, Mr. Tony. I have, at the moment, a 4.5L engine torn down, 4.5 heads already done before discovering the cylinder walls may need more than just a honing and standard pistons and rings put it.

I am considering, right now, going down your path.

[Tony H]

Project is alive and well but slow. You can go to 96.5mm/3.8" on cylinders and still have .175" thickness on cylinder walls but I would not go bigger because there will not be enough room for the heat ring by the middle head bolt. You will need custom pistons and the required 5.6 crank/rods.
Next detail I am addressing is the head gaskets. I have an outfit that can enlarge the bore with new heat rings on 4.5 gaskets. 5.6 gaskets are a different thickness and would require modification so I don't want to use them. If you have read through the post you have an idea of what is required. In theory pretty simple but some details that need working out. This is common place in the rodding world but most parts are off the shelf-it's just choosing the correct combination of parts. I have another thread on the pistons you might check out.

[RobertinMN]

Originally Posted by rwd4evr

He's progressing along.do you have a k-jet or d jet engine? I may have one to.sell if it comes to that.

I have a K-jet. Already had the heads rebuilt before finding out number 5 cylinder may need boring.

[RobertinMN]

Originally Posted by Tony H

Project is alive and well but slow. You can go to 96.5mm/3.8" on cylinders and still have .175" thickness on cylinder walls but I would not go bigger because there will not be enough room for the heat ring by the middle head bolt. You will need custom pistons and the required 5.6 crank/rods.

So you decided against the 5.6L stock pistons and cutting the heads down by 5MM?

Yes, I read the entire thread from beginning to end. I am very much impressed with your diligence and due diligence. I have always wondered why no one had ever really tried to improve these engines the way they do chevy's and even Porsche engines. Seemed odd to me and the guy I would have gone to is gone now--but his machine shop guy is still here........

[Tony H]

I don't think there is enough incentive or big enough market and one can install a aluminum 5.6 for probably less effort. I'm a long way from a completed project.

[Tony H]

Yes I decided against the 5.6 pistons. Too many unknowns to risk it. I can't remember what I said about the heads but at this point I'm going with stock 4.5 K jet heads. Once it is all sorted out I could try the 5.6 heads if I fell the need but i think just the displacement increase will give me all the extra torque/power I need.

[rwd4evr]

After beating the snot out of my iron block 4.5 for 23 hours of track time over 3 days, culminating in a full throttle for about 2 and 1/2 minutes 4 Lap closeout which resulted in setting my exhaust hanger on fire and temperature at about 230 degrees which I wasn't really that concerned about, I'm leaning more and more towards wanting to build a 5.0 or 5.6 ltr iron block.
I have no doubt that an alloy block engine would have been very unhappy. And I do this at every drift event without any issues. It runs about 205-220 on hot days all day long.
This thing is a beast. Just need more power.

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