Head Rebuild - New valve face clearance

[Ozzie Lou]

Hi,
This is my first post/query so wishing all well and have enjoyed finding helpful tips for keeping my girlfriend going.

I am in process of full engine re-build on a 1965 230 SL.
The head has been pressure tested and skimmed cleaned.
New valves, guides and seats being installed but the machinist has asked:

With the new valves/seats what clearance should be allowed for from flat  face of valve to the head surface?
That is should the valve face be slightly below the head surface when in the closed position? How much?

I've looked in manuals and forum and there is reference of a clearance of 0.9mm from face of valve to top of piston at 5% after TDC.

Am installing new pistons but same rods. So was going to measure the remaining original  bore from previous wear and ensure over 0.9mm.
Then would feel safe in having valve face level to face of head.
Or would it be prudent to allow some clearance from valve face to head surface ?

I'd rather protect the valves/pistons  and go conservative on this  clearance.
Could I ask of any past experience/ comments on installing new valves?


Thanks for your feedback in advance.

Lou

[Benz Dr.]

Intake valve recession should be .50 mm or about .020'' below the parting surface of the head. The reference of .9mm clearance from top of piston to face of intake valve at 5 degrees ATDC is correct.   

[Ozzie Lou]

Thanks Dr Benz.

If ever get time, I'll write up a post about the trials of an engine rebuild on a RHD.

Cheers,

Lou

[Benz Dr.]

New pistons are shorter than the originals so I usually deck the top of the block about .010'' to maintain compression amounts.