Pelican Parts Forums - Minimize head & cylinder damage from broken stud(s) by retarding timing?

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- - Minimize head & cylinder damage from broken stud(s) by retarding timing? (http://forums.pelicanparts.com/porsche-911-technical-forum/747786-minimize-head-cylinder-damage-broken-stud-s-retarding-timing.html)

Quote:

Originally Posted by Ronnie's.930 (Post 7424221)

No offence meant, but this is not the case - nine times out of ten, when the engine is operated with a broken stud, you are going to find some damage to the cylinder/head mating surface regardless of what sounds you hear or what changes you make to the timing. Anyone that says differently, such as some that are advising that it is ok to drive, even moderately, with a known broken stud, are just plain wrong and allowing their "wishful thinking" to get the better of them.

Hi Ronnie's 930.

Thanks - no offence taken :) If that if the case, then damage is already done since I have been driving the car with a broken stud for some time now, so... a little more driving this summer won't make all that much difference ;)

I know that some fly-cutting will be required during the re-build, and I'm OK with that.

Quote:

Originally Posted by NEWFIE 69 911E (Post 7424318)

Hi again,
Assuming fly-cutting will be required, how much cutting is typical? How much should I budget for this service? Thanks,

newfie

I can see that no matter what advise you are presented with you want reassurance that if you reduce the timing you can drive the car without any further damage.

As stated earlier any mileage put on the car in this state will induce further damage with or with out reduced timing. It is not only detonation which will cause problems but also blow by the reduced seal between the head and cylinder. It does not matter how much timing you take out you will still have combustion blow by at the reduced sealing area.

As you stated already you have run this way for 7k and I can not say how much damage is already done. It may be minimal and would only require a slight fly cut of the sealing surfaces. But if you had a lot of combustion blow by and eroded the sealing surface to a major extent then you can realize what Steve has stated, the replacement of a head and cylinder.

You have stated that you have a 2.0l at your disposal and could plop that in for this season. This would allow you to drive the car for this season while you and your son tackle the top end rebuild. Or you can continue on your present set mindset and drive the car for this season and take what ever consequences it may deliver. But do not cry if you have to replace the cylinder and head on your rebuild. Then again it may have minimal damage that would require minimal machining to correct but that is a risk you will have to wage.

Good luck on which ever way you decide.

Quote:

Originally Posted by mytoy (Post 7426990)

Hi Gary, many thanks for the comments and suggestions.

Yes, I have a running 2.0l from my 69E (but with Webers) that I could swap over into the SC. I have never really investigated the details of this transplant, but I know it is doable. I'm guessing the wiring and fuel pump conversion would be the biggest issues :confused: Maybe I'll start (or search for) a thread on 2.0l transplant into SC!

It really is the best option!