964 sealing ring groove specs: depth, width, position?

[klaucke]

Hi guys. I'm wondering if anyone has the specs for the location, width, and depth of the sealing ring groove in later 964 cylinders. I'm wondering about updating an early 964 w/ head sealing issues w/ this groove, so that it will mimic the later 964 jugs and have a sealing ring. Assuming the P&Cs are still in good shape and can be reused, it seems one could simply cut this groove and reface the heads in order to update to the sealing ring.

I would like to know the specs so that I can supply them if I decide to let a machine shop do this, or if I decide to cut them myself on a lathe or mill. Although I'd enjoy doing this modification myself, if it is reasonable to have this done when also having heads refurbished I'll just let the shop do it. If anyone has any ballpark figures, those would be good information as well.

Thanks in advance!

[ChrisBennet]

There isn't enough material at the top of the non grooved 964 cylinders to accomodate "retrofitting" a factory groove.
I've heard of people machining the cylinder tops for some sort of O-ring but I don't know the specifics. I might have some early style 964 cylinders laying around if you need some to experiment with (not a set though).
-Chris

[ischmitz]

Check here for what Walt @ CE has done for my engine. It's still absolutely leak-free after 16,000 miles. I don'thave the exact measurements but the drawing is showing how the fire ring is located between the head and the cylinder. The cylinders had to be machined.

Ingo

[klaucke]

So it appears that although the stock 964 sealing ring groove may not be viable (thanks Chris), that there are other working solutions like Ingo's flame rings.

Ingo, is it possible you could post the pics from the Rennlist thread here on Pelican so that people w/o a Rennlist account can see them?

[ischmitz]

Ok, let here is what I posted on the Rennlist forum a while back:

My 91 without head gasket leaked on all six barrels. A step was machined into the cylinder only and the heads were resurfaced. There was no modification for the fire ring done to the heads. As the pictures show the top part of the cylinder was left rough on purpose. It cuts into the sealing surface of the head to give some extra protection. Here is the schematic of the fire ring and how it is located between the head and machined cylinder top:



And here are the images of the head and the cylinder top prior to assembly:






Hope that helps. It is working so far for me,

Ingo

[MA7008O]

Sorry for bringing up and old post, but this solution to head gasket failure seems very interesting.
Any update or additional info?
Thanks,

[ischmitz]

45,000 miles later and there still isn't any sign of a leak. I'm a happy camper

[MA7008O]

Good news, thanks!!!!

[prschmn]

There are a lot of ways to skin a cat.
In my experience with 3.6 heads I've rebuilt they all become slightly warped
over time and heat cycles. For stock engines a good flat surface and careful
assembly is often all you need to have a leak free engine.