Cylinder Head Rebuild Questions

[OCG911T]

Gents,

Packing my 2.2T cylinder heads to send out for refurbishment and to open ports to S specifications for use with DC40 (Mod S) cams. I have two questions and am looking for advice.

1) Should I reuse good valves if I plan on revving this engine and driving harder than originally intended? If so, is it advisable to use Porsche OEM valves or are the less expensive options from TRW ok? The Porsche valves, particularly the exhaust valves, are significantly more expensive… I believe they are sodium filled and could be the reason they are $300 a piece?

2) Should I use sport springs, like the AASCO springs with Ti retainers? I would like to regularly rev the engine to the redline without worrying about valve float. Are stock springs suitable for this application or will the extra pressure just wear the cams and rockers more than it is worth with a Mod-S cam grind?

Thank you for your input.

Cheers,
Oliver

[edmayo]

First the stems should be measured, there is tolerance given in the spec book, too small and they should replaced. Second after regrinding the seat there should be measurable margin remaining, if that is too thin that also calls for replacement. I would still prefer ATE valves, how much have you shopped around for valve pricing? EBS racing, different dealers ? (Sunset Porsche?) that said we have used TRW with no known problems. Ask about country of origin, look at box, Chinese I will not use.

Altho stock springs will work fine if shimmed to a little more seat pressure, the Aasco ones are fine and have more than adequate seat pressure, if I recall correctly all you need is about 65-70 lbs. The ti retainers are a little overkill for your usage.

[OCG911T]

Ed,

Thank you for your response and advice. I will plan on the AASCO springs, and just use stock retainers because I can buy them separately from Patrick Motorsports. I have not shopped around much for the valves but will try to find reasonable deals on OEM valves and go that route.

Cheers,
Oliver