minimum valve clearance

[gtihop]

can anyone tell me what the minimum clearance is for the intake valve to piston for a 1983 911 3.0 ? Wayne's book says 1.5mm, I can't get quite that. It's more like 1.35mm. Is this acceptable for a street engine?
Thanks
1983 911 stock engine

[2.7RACER]

What's happening here? Is this a rebuild? What have you done to the engine? Is this possibly a cam timing issue? Have you measured all 6 intake valves?
When you get this close to minimum specs, actually under, you need to check everything very carefully.
Are the cams timed to the optimum position?
What was changed to the engine to get the piston valve clearance so close?
What method did you use to check the clearance?
If all the valves check out at 1.35mm or over and the cam timing is optimized, I'd run it. I would not run it over 7000 rpm's.
Double check the valve springs.

[gtihop]

there was no machining done on this engine. The cyl base gaskets are .25mm, the same thickness that was in before dissassembly. The cams are timed to .056", 1 pin hole more advanced than it was before dissassembly. (marked everything before). The intake clearance is measured by turning in the adjuster 1.5 turns and slowly rotating the engine by hand. At 7 deg ADTC, you feel contact. At 1.35 turns of the adjuster there is no contact to the piston. The exhaust valve has 3mm clearance. The engine won't see anything over 6000 rpm. Yes this is a rebuild.

[2.7RACER]

I would check every intake valve for clearance. All six.
It is likely each one will be different.
With the cam timed at 0.056", it is closer to 6 degrees BTDC. That's ok.
As you know these cams for the '78/'79 SC's were timed at .035"-.043". At 1 degree BTDC.
The same cams in the '84-'89 Carreras were timed at .043"-.055". 4 degrees BTDC.
I'd say after checking all six intakes, if they are all close, 1.35mm or greater, I'd button it up and run it.
If you are a little nervous, back up the cams one hole and recheck all the intakes.
You'll never notice the difference in performance.
I would not close the motor until I checked all six intake valve clearances. They will be different.

[gtihop]

thanks, I'll do that Monday. The spec for the cam in the bentley for the 930-16 engine is .055-.067". this is more than the older SC from 1978-79. I may just back the cams up and check all clearances. I'll post what my results are.