No less than 0.125" for both intake and exhaust. I've seen 'em run a little tighter, but you're playing with fire if you miss a shift or over-rev the engine. Pay attention to the valve in relation to the eyebrow radius too. Alot of times the valves won't kiss at the bottom of the relief but they'll hit at the edge of the eyebrow. Be sure to check your PV clearance with a solid lifter too; it won't do any good to check it with a hydraulic lifter.
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Jeff Chambers
Trophy Stock #3
11.86 Seconds / 113.8 MPH
Chambers Racing Team