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Join Date: Mar 2006
Location: Belgium
Posts: 160
964 - Valve guide wear limits / piston ring gap specs

Hello

Does anyone here have the wear limits for the intake and exhaust valve guides for a Porsche 964?

I've measured one exhaust valve (visually the worst one that was full off residual oils)
Valve popped out 1 cm, I measure ± 0.2mm if I wiggle it up and down.
I can't find above requested wear limits in the manuals?

Regarding the pistons (this is what I found in an earlier conversation);
What should piston ring gaps be on a Porsche 964?
Top compression ring: 0.15mm??
2nd compression ring: 0.3mm??
Oil seal ring: between 0.15 - 0.3 mm??

Are these numbers correct?

Old 01-06-2025, 06:13 AM
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Your guide measurement doesn't sound too bad but you're probably going to have a hard time findiing rings that won't already have a much larger gap.
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Old 01-06-2025, 07:02 AM
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I have read somwhere that guide wear limit is 0,15mm.....but I can't find this number back in the manuals that I have.
Also I don't now if this limit is for inlet and exhaust

Regarding the piston rings, are you telling that new mahle rings already have a bigger tolerance then that I mention?
Old 01-06-2025, 07:11 AM
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Can't tell you what Porsche says but always a bit more for exhaust. I hone guides to about
.03 intake and .05 exhaust. And yes the new rings are likely going to have much bigger gaps.

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Mark
www.exotechpower.com
1981 Targa-messed with. 91 C2 supercharged track rat
Radical Prosport-irritates the GT3 guys
40 years of rebuilding services
Old 01-06-2025, 07:19 AM
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