Henry - Supertec spigot adapter?

[andrew15]

I seem to remember that Henry at Supertec had come up with an adaptor or method for usings 2.0 cylinders on an early case that had it's spigots previously bored to accept 90mm cylinders. In essence allowing you to go back to stock configuration.

For the life of me I can't find it - anyone out there remember this. Or better yet, Henry can you shed some light on this?

Regards,
Andrew M

[Henry Schmidt]

Andrew
The insert is made of high quality aluminum (20-24) and is basically a cylinder with a 8.5 mm high flange, 98 mm in the minor od and 107 mm in the major id. The overall height is 35 mm..
We originally designed this process for building a 7R cased (the strongest) into a 2.0 race engine. The Porsche community being as stubborn as it is, rejected the idea in favor of the early aluminum case.
We had the opportunity to restore a 70 2.2S engine that was converted to 2.5 and needed to convert it back.

The process is involved but fairly straight forward.
You insert the case (CaserSaver) and machine the spigots flush to the main case level.
Next the spigot inserts are glued (Epoxy Patch) in place over top outside edge of the CaseSavers.

We go the our favorite powder coating company to have the case baked so that the epoxy cured to it's hardest possible condition.
The case is then put into the mill for final machine work.
Each spigot must be decked and bored to the correct height and size.
That's it in a nut shell.

[andrew15]

Thanks Henry - That's exactly what I was lookign for. I'll have to give you a call when I'm further along with the new project.

AM

[andrew15]

I was just thinking - would it be possible to create juut a sleeve that would fit between the bored spigot and the original 84mm P&C without the case machining?

My thoughts were: the spigot while thinner is already supporting 90mm cylinder and the 84mm cylinder really jsut needs to be located in the bore.

I don't really have any technical background, so I may be talking out my butt here, but would that work and be simpler to create?

AM

[cnavarro]

The way Henry has done it really is the best way shy of making a custom cylinder, which is usually my method of correcting things. I have done the same with great success.

You could technically make a sleeve with a .002" clearance between the original skirt and the new, larger o.d. and Loctite 620 it to the cylinder, but doing it this way will constrict the expansion of the skirt when the cylinder gets hto, as the "epoxy" does not conduct heat like the aluminum does. How much it would constrict the bore is a great question and whether or not forcing the cylinder to conform might cause the cylinder to crank is another great question.

[andrew15]

Sounds reasonable to me Charles!
I'm currently thinking I have 3 options:
- Rework the case per Henrys solution
- Custom Nickies from LN
- JE's for my 90mm cylinders (Least desireable)

AM

[Henry Schmidt]

We looked at the possibility of a simple sleeve and decided against that option. There is no good way to hold it (the spacer) in place and it still leaves you with a marginal spigot flange for both support and sealing the cylinder base. Although the 90mm conversion was common it was never a quality conversion on a 4R case. After you bore the spigot out to 97mm what you have left is a very thin flange.
Even if you use the top quality LN Engineering's Nickies™ cylinders you are left with a poor support base.
Our reconstruction method actually makes the case as good as new or maybe better.

[andrew15]

Thanks Henry, I knew that there was probably a reason a sleeve wouln't be all that great - I just didn't know what it was

AM