3 replies to this topic

[Gremlin]

Will original valve springs from an an original standard 998 work in a 12G295 head?  If so, will the  spring 'caps' where the collets sit work on the original springs?  Also, will the valve stem oil seals work because there is not a 'groove' cut into the valve guides?

[Cooperman]

If you are not changing the cam you need to measure the fitted length of the springs on the original head then measure them on the 295 head. They should be the same +/- about 0.050".

The 12G295 always had double valve springs to handle the higher revs of the 998 Cooper engine with its better cam.

If changing the head and valves it's a good idea to fit new valve springs as, presumably, you are seeking better performance.

Are you not changing the valve guides? It's always a good idea to change them and to have the valve seats re-cut and the valves re-lapped.

The latest valve stem oil seals should work OK.

[Gremlin]

Thanks Cooperman, I was only planning on using the original valve springs as we are not changing the cam, so we don't need the double springs and the original springs have only done 38,000 really easy miles.  I'm getting the seats replaced with hardened ones and obviously re lapped, and the head skimmed by 63 thou to bring the compression ratio up to 10:1.  Do you know if the spring 'caps' will work with just the single original spring?

[Cooperman]

So long as the spring caps are the correct ones for the valves there will be no problem. The single groove valves and collets can only be used with the correct caps. Caps for the 2-groove valves have different collet angles and MUST NOT be mixed up..