94mm flycut heads on 90mm jugs...

[dubsquared]

Is this possible? Thinking that a ring machined to the right dimensions would make it a no brainer. Does somethig like that already exist?

tried the search, came up with nothing...
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[Glenn]

Try masking tape.
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[dubsquared]

good answer, expected more from you... thanks.


The idea here is to put the heads on a friends 1835, but it looks like it isn't too hard to put the 94mm jugs in a case cut for 90.5, so that may be a better route in the long run.
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[Glenn]

I'm confused....

Heads off a 1835 are the same diameter as 90.5, not 94. (unless that are thick wall 92s).
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[cal63look]

You can get your barrels turned down which would make a 94mm fit into a 90.5 for the case side of the motor, you have to have the heads opened up to 94mm though.

And i beleive Kona has mentioned something about being able to run say 94mm heads on 90.5s or 92mm pistons somehow? Might want to contact him. Other than these questions I dont have a clue what your talking about then....?

[dubsquared]

I have heads, fly cut to 94mm for a 1915. Changed my mind, want to run a different head.

My friend has an 1835 in his car, looking for a way to use these heads on his motor.

My first inclination was to machine a ring to center the 90.5mm jugs on the 94mm heads.

Then I did some more reading on here, and it seems that there are 94mm jugs out there that can be machined/bought to fit a 90.5mm case. Since once you have the heads off, pulling the jugs and swapping pistons is pretty minor(relatively speaking), I figured we would just build him a 1915 and use the heads as is.

First, am I crazy to think that a ring could be machined to use the 94mm heads on a 90.5 jug. I know the ring could be made, but would that be adequate for making the heads work.

And second, did I misread that a 94mm jug can be made to fit a 90.5mm case? Is that not what you run on your engine?
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[Nater]

[dubsquared]

I think the best option so far, for putting these heads on the 1835 is to just bump it up to a 1915 with the AJ Simms 94mm slip-in pistons.

Sorry if all of this was so confusing
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[EZGZ]

First you better measure your friends 1835 and see if the pistons are 92 or 90.5........1776???
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[lostinbaja]

I have seen people bolt heads cut for 94mm cyls. on top of 90.5 cylinders with no problems. I know of one engine that has been running for years that way. The sides of the cylinder do not do anything to help seal the head to the cylinder. The seal is made at the top of the cylinder.
Rimco used to shrink collers around the top of cylinders to reinforce the cylinders for high boost applications but I doubt if it will help improve the seal.
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[dubsquared]

[Dougy Dee]

If the combustion chambers on the 94mm heads have had the valves unshrouded they may be unshrouded too far for the 90.5 or 92mm cyl's. Take the cyl you are using and center it to the head. Look inside. Is the edge of the unshrouded chamber hidden behind the edge of the cyl??? Then you'reSOL. You'll need to use the 94's. If not centering them up can be done without spacers being made up. You wont be able to use copper gaskets for deckheight as they wont stay in place. You'll need to control your deckheight with shims under the cyl's.
I have machined up rings for spacers before but found it to be not worth the effort. As long as the cyl's sit level and flat, site across them with a straight edge, you will be OK.

Good Luck

[Type 5 Joe]

-Or if you can afford a few cc's minus in the combustion chamber.....

You could machine a counter-bore (step) in the heads that fit the O.D. of whatever cylinder you want. It would look like a factory stepped head, but the cylinder would seat inside the step, not on it.

I would not just slap the heads on with no spacers / counter-bore or anything...

I would make sure there is "meat" around the sides of the combustion chamber like previously mentioned. If there has been a full un-shrouding for 94's, you have to run the 94's

Good Luck, - Joe
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[turboblue]

As long as the combustion chamber is inside the cylinder you can use an o-ring to center the head.
It will burn off later but that isn't an issue.
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[dubsquared]

Combustion chamber is un touched.

Didn't think about an oring... interesting idea. The heads will stay centered after it burns out?
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800+hp water-cooled
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[dubsquared]

[quote="Type 5 Joe] You could machine a counter-bore (step) in the heads that fit the O.D. of whatever cylinder you want. It would look like a factory stepped head, but the cylinder would seat inside the step, not on it.[/quote]

This would probably be our best easiest bet, plenty left in the chamber to make that happen.
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800+hp water-cooled
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[Messy Jesse]

When you say "fly-cut" I think you mean the heads are bored for 94's. Fly cutting is something else done to increase compression.

I think you should just have the case cut for 94's. 94mm cylinders are better than those thin walled 92's because they have more meat on them. However, I agree with Nater that you could have a set of the thick-walled 92's turned down to slip into a 90.5-92mm bore. I believe that is what Glenn had done on his motor. That would allow you to run the 94mm head, have some nice, thick cylinders, and keep your displacement at 1835.

I don't think you should machine down the 94mm cylinders to fit the case. There's just not enough material there to risk it. Some kind of machined spacer to fit the heads also sounds like a solution for you, but I like the idea of the thick walled 92's best.

Good luck

[VanderBus]

RIMCO still lists sleeves to adapt 90.5 cylinders to 94 heads if I'm reading thier catalog right.

http://www.rimcovw.com/rimco_pg_4.htm

I'm curious if they sell these outright or if they press them on your cylinders for you.
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[turboblue]

[dubsquared]