993 valves in earlier heads

[Speedy Squirrel]

I have always used Porsche valves in my 930 builds. I think there is a pretty good case that the sodium cooled exhaust valves keep pre-ignition at bay.

The thing is, they have the large diameter valve stems. Additionally, 993 valves come with sodium intake valves. The skinny 993 stems also flow more.

So, has anybody had special guides made to adapt the 993 valves to the earlier heads? Also, can you cut the intakes down to 41.5mm without difficulty?

[Henry Schmidt]

The short answer is that you can trim a standard 993 valve guide to fit and early head.
The outside diameter is the basically the same (.5140 vs .5145") but the length is longer.

9mm 2V 911 IE Std 0.3546" I.D. x 0.5140" O.D. x 2.055" Long
VS.
993 2V IE Std 0.3149" I.D. x 0.5145" O.D. x 2.205" Long

[Speedy Squirrel]

Thanks Henry. Glad I won't have to round up some phosphor bronze round stock.