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gvr4 · 12-30-2012

Do you deal with metals at those tolerances? If so, I'm sure you are aware of the changes that will occur over the temperature range seen by a component like a valve. 0 clearance at 70 degrees means -.025" or so at 600-700 degrees

There's also a phenomenon called valve float that really tends to make a mess out of things if there's too little clearance. It's easy to see how a pushrod engine would end up with quite a bit of valve float because of all the extra mass in the valve train. But valve springs in an overhead cam engine have a lot less inertia to contend with, and I'm wondering if this translates to tighter acceptable clearances.

12-30-2012	#3
gvr4 New Member Join Date: Sep 2012 Location: North Branch Drives: I walk. Too many broke vehicles Posts: 40	Re: Piston to valve Clearance? Do you deal with metals at those tolerances? If so, I'm sure you are aware of the changes that will occur over the temperature range seen by a component like a valve. 0 clearance at 70 degrees means -.025" or so at 600-700 degrees There's also a phenomenon called valve float that really tends to make a mess out of things if there's too little clearance. It's easy to see how a pushrod engine would end up with quite a bit of valve float because of all the extra mass in the valve train. But valve springs in an overhead cam engine have a lot less inertia to contend with, and I'm wondering if this translates to tighter acceptable clearances.