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-   -   3.6L head to cylinder sealing ring modification question (http://forums.pelicanparts.com/911-engine-rebuilding-forum/927310-3-6l-head-cylinder-sealing-ring-modification-question.html)

archnraft 08-30-2016 08:05 AM

3.6L head to cylinder sealing ring modification question
 
Hello Gentlemen,

I have a set of '90 100mm cylinders without the sealing ring grove.

My question is, can the sealing grove be machined into these cylinders so that they can be made to work with a set of '90 cylinder heads that HAVE had the sealing ring modification? Or, would the heads require a different set of cylinders and pistons.

Thanks in advance for your help on this, any details you can kindly provide would be greatly appreciated.

Kind regards,
Anna

Steve@Rennsport 08-30-2016 08:45 AM

Hi Anna,

Its the early HEADS that get machined for sealing rings; the cylinders simply get a small cut to aid the process.

If your 100mm P/C's are in excellent condition well within spec, you can have them machined for sealing rings. If they are close to, or beyond spec, I would recommend the newer ones that use sealing rings.

Your heads do not need any specific work to accept the later cylinders.

Hope this helps,

archnraft 08-30-2016 10:25 AM

Thanks again Steve. You are always a big help!

Can you share what that simple cut is?

The cylinders I just bought have less than 10K on them.

Steve@Rennsport 08-30-2016 12:18 PM

Quote:

Originally Posted by archnraft (Post 9261306)
Thanks again Steve. You are always a big help!

Can you share what that simple cut is?

The cylinders I just bought have less than 10K on them.

We put a slight bevel on them to "bite" into the sealing rings.

archnraft 08-30-2016 01:51 PM

Thanks again Steve. Is this a costly exercise? Have parts going to a machinist local to me here in NY, but if cost effective I'd like to give you my business as you've always been very helpful.

Steve@Rennsport 08-30-2016 03:59 PM

It does take some time to machine all heads and cylinders for sealing rings.

Contact me directly for pricing. :)

mikedsilva 08-31-2016 01:04 AM

Quote:

Originally Posted by Steve@Rennsport (Post 9261136)
Hi Anna,

Its the early HEADS that get machined for sealing rings; the cylinders simply get a small cut to aid the process.

If your 100mm P/C's are in excellent condition well within spec, you can have them machined for sealing rings. If they are close to, or beyond spec, I would recommend the newer ones that use sealing rings.

Your heads do not need any specific work to accept the later cylinders.

Hope this helps,

This confused me.. I always thought it was the CYLINDERS that were machined to accept the ring..

K24madness 09-03-2016 02:21 PM

Quote:

Originally Posted by mikedsilva (Post 9262203)
This confused me.. I always thought it was the CYLINDERS that were machined to accept the ring..

The cylinders are machines to accept a sealing ring if there is not a grove present. This process duplicates the factory's newer method of sealing the heads/cylinders.

When building a turbo or very high performance motor you can also weld the lower two fins on the head and machine a matching grove into it. This helps prevent the heads from dancing around under extreme conditions.

Stevie's comment of machining a small cut in the head sounds like a way of helping the sealing ring in the cylinder achieve a better seal. Not necessarily a full grove like the flame ring on a turbo motor.

archnraft 09-03-2016 07:48 PM

Hi,

Now I'm confused ��

Steve clearly stated the primary groove is in the head, the secondary bevel at the cylinder mating surface. Now, we are discussing primary groove in cylinder?

Just like clarity for all viewers - thank you.

Best,
Anna

Steve@Rennsport 09-04-2016 10:46 AM

Quote:

Originally Posted by archnraft (Post 9267439)
Hi,

Now I'm confused ��

Steve clearly stated the primary groove is in the head, the secondary bevel at the cylinder mating surface. Now, we are discussing primary groove in cylinder?

Just like clarity for all viewers - thank you.

Best,
Anna

Hi Anna,

For clarity's sake,....:)

Quite obviously, I cannot speak for anyone else, however I can tell you what I do with these early engines. :) :)

Since the early heads and cylinders do not have any gaskets or sealing rings, we machine the heads to accept a 993 sealing ring and make a small modification (as previously discussed) to the tops of the cylinders to ensure best results.

This permits one to use their current early pistons & cylinders, provided they are still well inside wear tolerances.

I hope this helps,

archnraft 09-04-2016 02:43 PM

Well recieved Steve. Thank you for clarifying for all :-)

Cheers!
Anna


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