Hi Besser
they do make very good shims and lash caps I use a lot of them in the BDA,s and the dato,s I do dato,s are one of my favourite motors, I have some really good cams for them, if you are going to use 6mm stem valves in you motor be careful as they walk around badly with a good cam and high reves (8000 RPM), you will have to give them .025/.030 tho clearance between them or they will touch each other,there is no HP gain using valves stems that small in a mini just more head ache.
Graham Russell

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"It's better to be not informed than ill-informed"

Hey GR thx for the heads up. will keep an eye on the valves however they suit my needs.

Really interesting comment from GR about the 6mm stem valves needing wider clearance between inlet and exhaust heads, a lot of the UK engine builders are moving to 6mm stem valves.

Can anyone advise on the calculation (if there is one?) to determine how thick a lash cap should be?
I guess you then subtract that from any setting of the clearance gap?

The ones on the link to Precision are all stated at being 3mm deep but with a variety of thicknesses.

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'98 Mpi Sportspack + 7 port alloy head

Simple answer is you have to make the room as they won't fit. Make sure you have the valve seats as high as possible to pull the valve away from the rocker and pack under the rocker shaft towers as much as possible, then a custom spring retainer and you might get there. or custom everthing and correct geometry to be sure to be sure

The need for a lash cap to prevent tip wear says you need to buy decent valves.

A roller rocker produces less friction than a standard rocker arm and when set up correctly travels less distance across the tip.

All decent 214N valves will have a stellite tips.

If you feel you need to run lash caps you want OAH (overall height) of .120" with a depth of .060".

Meaning you'll have a shim on the valve tip of .060" and a shoulder of .060" to keep it on. So for it to come out you'd need valve clearances of above .060".

You'll also have to reset (or set) your rocker geometry and possibly adjust your pushrod length.

As for 6mm stems. If a NASCAR can get away with running 6mm stems @ 150mm OAL with a head of 53.975mm using a 1mm seat @ 55 degrees at 9500 rpm for 500 miles..... Might want to have a look at valves/guides/installer?

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Breaking heaps of stuff isn't the same as R&D since the "R" implies you actually did some research

G&H is the most applied practice by performance engine builders

G = Guess & H = Hope