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Porsche 964 engine reseal questions.

I'm completing a reseal on my 964 and thought I'd start a specific thread for advice rather than posting in others threads. Right now I'm in the disassembly stage and have a few questions.
Old 04-21-2017, 01:21 AM
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Firstly, three of the tappets/followers have some pitting. It doesn't look bad to me or is it?

Old 04-21-2017, 01:23 AM
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The thrust washers and shims behind the cam sprockets are not in the correct sequence and one thrust washer has the groove in the wrong orientation. Why did the factory specify the sequence and orientation it did?
Old 04-21-2017, 01:29 AM
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The cylinders were machined to accept a gasket at the last rebuild. This process appears to have weakened the edge and two cylinder bases have chips. Are these chips critical to sealing i.e. Does this mean new bases are needed for the two cylinders?
Old 04-21-2017, 01:34 AM
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I've reused rockers that look more like your second and third photo... I probably would had had the first one refinished or replaced. I will guess that someone on here will tell you to replace all of them, and they may not be wrong.
Old 04-21-2017, 05:07 AM
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Makes sense that the rocker pitting is at the heel, because that is where the spring is most compressed so the forces are greatest. Me, I'd send them off to CGarr in Michigan, but that may not be such a good option for you. He has rejected a couple of mine as being too pitted for sensible regrinding and use. Buying a couple of new ones ought not to break the bank if all the rest are OK.

Isn't the cam thrust washer beveled on one side? I think I recall doping out why - what it bears upon is narrower than the shim side. I suspect you can just put them back in the correct order and orientation. The key on reassembly is confirming chain wheel parallelism, which is the function of the washers.

I've not seen mention of cylinders chipping out like that, but I've no experience with the 964. Maybe it is common? The seal is the inner surface of the cylinder pressing against the head. The seal ring is there as insurance, but useful insurance - Porsche's experiment with the 3.2s with the seal omitted and the top of the cylinder beveled for more compression of the mating surface seems not to have worked as well as hoped, so it was back to the CE ring.

If no on chimes in on this cylinder business, e-mail Henry Schmidt or Steve Weiner, both of whom graciously contribute to this forum from time to time..
Old 04-21-2017, 03:59 PM
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I'll give them a bit longer to see this. In the meantime I'm tantalisingly close to splitting the case the hold ups are the piston wrist pins on pistons 4 through 6.

Pistons 1 through three were easy. I removed a circlips on each one and the wrist pins slid out with finger pressure.

Pistons 4 through 6 won't do the same. The wrist pins all look like they are hitting the piston. https://youtu.be/ytTTtgmMJJ8

Was I lucky with 1 through 3? Is some force required to extract these pins? I don't want to damage the pistons.
Old 04-23-2017, 12:22 AM
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Hi John,
The chipping at the edge of the cylinder sealing surface is, I'm afraid, a result of the machining that was done to accept a sealing ring. This left a very thin surface at the edge. It could possibly be welded, bored and replated, but I would consider replacing the chipped cylinders myself. (I have an extra set of 964 cylinders and Pistons. PM me if you're interested.) As to the rockers, how do the cams look? Because the cams and rockers wear together, I have never been comfortable just replacing one or the other. My own 964 cams were started to show some spalling, so I had John Dougherty regrind them to. 993SS spec and also had all the rockers regrind.
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Old 04-25-2017, 12:58 PM
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Hi John,
I had Franklin cams in Auckland repair some cams for a 964, they refaced the rockers for me also. It was only a couple of weeks ago so they should remember. Give Brad a call and see if he can help you.

We may have some used cylinders here if you want me to have a look. Probably only the early type with no sealing groove.

Looks like your finding plenty of issues which is a shame.

Keep up the good work.

Cheers
Reuben
Old 04-26-2017, 12:47 AM
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Thanks everyone for the above replies. It all helps as I clarify the way forward. The engine only leaked at one place, the nose bearing. It was leaking two litres of oil every 1,000 km so had to be sorted. I've split the case and am researching sealing options, of which there are many

Btw the ugly item on the front of the bearing is a half removed Tom Amon collar. It is easier to remove when everything is disassembled.
Old 04-26-2017, 11:06 AM
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Originally Posted by Reuben.L View Post
Hi John,
I had Franklin cams in Auckland repair some cams for a 964, they refaced the rockers for me also. It was only a couple of weeks ago so they should remember. Give Brad a call and see if he can help you.

We may have some used cylinders here if you want me to have a look. Probably only the early type with no sealing groove.

Looks like your finding plenty of issues which is a shame.

Keep up the good work.

Cheers
Reuben
Hi Reuben, thanks for that lead. As the cylinders don't appear to be leaking from the chips and everything else is good on them I'll likely refit them. If I get leaks I'll just pull it back down. It's only time.

Btw what is the oil passage machined into the block for? Mine was full of 574.

Old 04-26-2017, 11:10 AM
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