968 valve spring height

[sgl1966]

As per the heading , does anyone have the installed valve spring height to hand for a 968 .

[Waylander]

That’s like asking how long is a bit of string

Depends if the seats have been cut or replaced, on the valve wear, original length of the valve, thickness of the spring topper, that’s why they have hydraulic tappets

But I guess there is a maximum limit somewhere in the manual

[pauly]

Not much help I know, but I've got a diagram of the 8v 944 setup somewhere. I remember years ago when I had modified Essex V6 and 16V Cosworth heads, the spring seats were shimmed and springs checked for coil binding at the correct installed height.

[sgl1966]

That's why Paul , the shims and springs were all mixed up on dissasembaly so after valve spring height to stop binding .

I have the information from the WSM for an 8 valve but don't have 968 height .

[Waylander]

the 968 manual is here

http://pdlibrary.co.uk/Manuals.php

[sgl1966]

Thanks waylander but couldn,t get link to work and struggled finding info in 968 wsm . Found these measurements from a wsm for Porsche 928s4 which should work unless anyone knows different .

[pauly]

Install all the valves, and measure if they're all the same depth in the combustion chamber. Add or remove shims to equalise spring pressure, then compress springs to equal cam lift, and check for coil binding? I just made that up, so rely on it at your own risk .

[Waylander]

The link works I just tested it

And also the head is pretty similar to the S2 so if no information in the 968 manual, then it always falls back to 944 manuals


https://porschedocs.s3.eu-west-2.amazon ... 8_wsm1.pdf

that is the link copied off the website

[sgl1966]

I'll pass on your instructions to my engineer and have him pass comment , you never know .

Still get an Error 404 -Not Found code with the link but thanks anyway . I did look for S2 but could only find details about the earlier S model and I'm led to believe that they had a different height again , still happy with the S4 , two S2 engines glued together !

[Endoman]

On the S2 89 onwards Engine M 44.41 the figures are:-
Installation lengths
Inlet valve 38 + 0.5 mm
Exhaust valve 37 + 0.5 mm
Page 15-34 WSM
Checking page 15-133
Although similar the 928 uses different cam profiles.
When I was building engines I would do a trial assembly with cams to check for coil binding. We used Ford springs in an MG cylinder head with Mini high lift roller rockers and vernier cam timing. Not exactly standard. 20 thou gap betwen coils to allow for valve bounce. That was in the '70s, 135 bhp from 1650 cc @ 8300 rpm.

[sgl1966]

Thanks Endoman , just what I needed .
Impressive performance figures for the 70's or 80's come to that . Don't think my Mk3 cortina made those sort of figures back then , 90hp on a good day from 2 litres .
As you have probably guessed I am not installing the springs myself but the engineer replacing the valve guides requested it .

[RyanGK]

the 968 manual is here

http://pdlibrary.co.uk/Manuals.php

Thanks! We need one for the incoming 968 project. My uncle took a quick look and it needs some suspension works. We'll just finish installing the set of tires and suspension from 4Wheelonline onto the Wrangler this week before we take her in.