16 replies to this topic

[Cooperman]

I don't have a cooper head, it's a bog standard 998 head that's been reworked. It's the "stage 3" head from mini sport.

So would I have a problem if I fit the spacers when I don't actually need them?

You could measure the total depth of the head with vernier calipers, then compare to a standard 998 head to see how much has been skimmed.
It's likely you won't need any shims, but if you have some you could fit them up the the difference in depth between the two heads.
If you don't have the head depth for a standard 998 I could measure one tomorrow. Just let me know.

[pogie]

I was given two set of shims with my MED rockers and was told that the way to work out if you need to use them is to measure the lift of the cam and then measure what lift there is at the valve.

On the trial build I measured the cam lift with a dial gauge on the top of the pushrod for No2 valve (cylinder 1 inlet) which I found to be 8mm which meant that I should be getting 12mm lift at the valve. So I fitted the rockers without shims and measured the lift at the valve by using the dial gauge on top of the valve cap and I found 10.9mm of lift, with thin shims I got 11.9mm of lift and with the thick shims I got 11.5mm of lift. Obviously the thin shims were way to go and for the sake of an hour’s measuring I found roughly 10% more valve lift than if I hadn’t bothered.

Edited by pogie, 12 November 2011 - 09:20 PM.