Rennsport Systems Community

Hi.
Anyone in here that can answer if the Cam profile 120/104 can be used with new stock valvesprings and retainers? I am firstly thinking if the stock springs can handle the ramp acceleration of the 120/104.
I have safely used original valve springs with amongst others the 964 profile without any problems in an earlier engine,
Would be very happy for any answer.
I have been using Aasco high performance springs and TI retainers untill now, but fear that thats most of the reason for badly worn rockers and camlobes.
So I really hop some of you in here can share som light on this.

Webcam 120-104.jpg.png

FWIW, I've never had camshaft/rocker wear problems using those cams and I've installed several hundred pairs.

The biggest single reasons for cam/rocker wear are clogged spray bars and using incorrect oils that do not contain sufficient ZDDP to protect those parts. in some cases, incorrect break-in procedure was the culprit, however those are human factors.

Stock valve springs are OK to 7K.

'78 & later factory retainers are sintered metal so those should not be used in any high RPM engine.

Thanks a lot for your answer Steve.

Can the Aasco TI retainers be used with stock valve springs?

Is it the retainer with 901 105 421 03 the one you refeering to? I see that it is the same part number before and after -78.
Does that mean that Porsche changed the metallurgy in them and made them in sintered metal from -78 and used the same part number?


Cheers
Eskild

Stock springs can be used with Ti retainers, however its not something we ever do. When RPM levels mandate the use of better springs & retainers, we use both to prevent both valve float and retainer failure. Not needed unless RPM levels exceed 7K.

Porsche stopped using machined steel retainers when the 3.0 engines were introduced.