1.2mm deck height ok?

[squidmarks]

My deck heights are measuring about 1.20mm using the 0.5mm coppers shims that came with the gasket kit (82SC, stock KS P&C's). What would you experts suggest? Should I add a 0.25mm shim to bring it to 1.45mm or is 1.20mm ok?

Thanks.

Geoff

[Henry Schmidt]

I would should for .040" on a stock 911 SC.
If the cams are stock .040 is ok.

Always check piston to valve clearance for peace of mind.

[squidmarks]

Henry,

The cams will be the 964 profile.

0.04" works out to just a shade over 1mm (1.016mm). Wayne's book suggests a deck height b/w 1.25-1.50 mm (0.049-0.059"). So at 1.2mm, I'm on the low side of what Wayne suggests and on the high side of what you suggest.

If I err on the high side (i.e. more clearance) I am throwing away a significant amount of compression ratio?

What is the best way to check piston/valve clearance? Just turn the crank over once the valves have been adjusted and feel for resistance at each TDC?

Thanks for your help.

Geoff

[ChrisBennet]

Goeff,
Any chance you are confusing deck height and valve clearance?
Deck height is the piston to head distance usually measured at the very edge of the piston.
-Chris

[88-diamondblue]

Geoff,

Anything between 1 and 1.5 should be fine. I wouldn't go any higher than you are right now. Like Henry says just do a valve clearance check to make sure your valve clearance is ok. Do a search here on the engine rebuld forum and there are many posts on recommended deck height. Mine was just over 1mm on my Carrera rebuild.

[Jeff Alton]

I think wayne's book does in fact suggest the larger deck height. A part of the book I ignore. Henry's recommendation is the same I have heard from other builders and it is what I shoot for as well.

Cheers

[squidmarks]

Excellent. Thanks for all your responses. I'll leave it at 1.2mm and check the piston to valve clearance when I get it together.

Thanks.

Geoff