Choice of valve springs for camshaft
 

I have a question. Is it safe to use genuine Porsche valve springs and retainers with the Webcam 120/104 camshaft profile? Or is it an absolute must to use performance springs and TI retainers?

After what I have read the genuine springs handles up to 11,8mm / 0,465 inch lift.

A friend of mine has been using genuine springs with no problem for 6 years in a 3.4 short stroke Carrera engine toghether with a cam profile that has 0,490 inch /12,446mm lift

http://forums.pelicanparts.com/uploa...1564650609.png

Here’s the specs on the 120/104 cam:http://forums.pelicanparts.com/uploa...1564651503.jpg

I am running a very similar cam. Dougherty DC65. I run Cat cams 911 springs which are only a very slight amount stiffer than stock, yet certainly not as stiff as Aasco springs. You're in Europe so it will likely be easier to obtain. Highly recommend Cat cams springs.

Good tip on the CatCams springs. Sounds like a great compromise between stock and the super stiff race springs. I've always been concerned with the pounding the valve seats, retainers, rockers, etc receive when running race springs.

I recall a similar question in an earlier thread. Fred Apgar had responded that he always used stock springs that had been cryo'd in his race motors. Thread link:
http://forums.pelicanparts.com/911-engine-rebuilding-forum/1028220-large-port-sc-valve-spring-retainer.html

When I was looking for springs I measured the Stock spring at 315 lbs per inch a increase of 45 lbs per inch (360) was not considered detrimental at all. The folks that use a spring from another application particularly a spring used for a push rod motor with inordinately heavy seat pressure is what gives springs a bad name when wear is considered. It also didn't help when Web Cams had their hard face overlay issues which I since believe they rectified.

regards