Quote:
Originally Posted by carrerarsr65
(Edited) I have a 79 SC 3.0 with J.E. 10.5:1 pistons. Using the solder method I seem to be getting 1.9-2.1 mm deck height and, without a base gasket, 1.70mm. Ollies rebuilt the rods. Everything else is new from the bottom up. I have been torquing the head bolts to 25 ft·lb.
My question is, is 25 ft·lb enough? I talked to Walt Watson at Competition Engineering and he says I can get away with a higher deck height, say about 1.5mm. I really don't want to leave anything on the table. Any thoughts?...
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I think you are mixing some terms here. Deck height clearance is the distance from the top of the piston to the top of the cylinder. That measurement does not include the dome. So, in your picture, if your piston is at TDC, you measure the top of the dome to the top of the cylinder and subtract your dome height. Your spec sheet will have that number. Collective wisdom says 1.25mm to 1.50mm is the target:
http://forums.pelicanparts.com/911-engine-rebuilding-forum/575057-deck-height.html
You seem to be saying you've measured dome-to-valve clearance with the solder method. I want to point out that you have THE expert's word here. I'm not sure what you want to hear. I've read where race engines with closely managed tolerances will go under 2mm for exhaust clearance. If Mr. Watson has given you advice on this, run with it. I'm unclear on how the torque spec fits into the question.
An old
discussion about this topic...
Good luck!