888 valve seat blanks - size

tubbylad

Hello all,
hope we are keeping safe and well.

Does anyone have the basic dimensions for replacement valve seat blanks please.
Std valves on an SP4 - 30mm & 34mm

I'm considering making some but can't find the blank size.

Thanks.

Martin

Mr.R

Hi Martin,

Unless I'm completely mistaken the OEM valve sizes on the SP4's were 33/29's?
The 34/30's being fitted to the '91 Corse 888's, very rare SPS aka SP(4)S and the later SP5'S

I can't help you with the sizes you need here, but can point out that the cylinder head castings are big enough to take oversize valve seats.
The valve seats in the SPS/SP5 and early Corse 888's are big enough to fit 37/32mm valves (and possibly even bigger?) without the need to change the seats.
So it shouldn't really mater if you make yours just a little oversize from those that you have already.
I've fitted 36/30's and 37/32's into 916SP (originally the same size valves as the 888 SPS and SP5'S) and "G" spec Corse heads without any problems.

Steve R