Choice of valve springs for Webcam, profile 120/104 camshaft

[Litle brother]

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

[Steve]

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.

[Litle brother]

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

[Steve]

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.

[Litle brother]