I need to get some valves for a pair of bare 57 312 G heads.  I see 1.92, 1.94 and 2.020 intakes and 1.60 and 1.625 exhaust valves offered.  Do the oversize valves cause any piston clearance problems?  or...are the slightly oversized valves allow for wear and cleanup of a valve job?

Paul J. - '57 E Code

There should be no piston to valve clearance problems with using larger diameter valves in the G heads with the normal camshaft offerings.  Larger diameter valves tend to help in not sinking the valves as much during a valve job as new material at the outer edge of the seat is used to seat the valve.  The main thing to watch out for when using non-stock valves is to insure that the valve lengths and keeper locations are close to the original.  Otherwise, valve spring installed heights and rocker arm geometry issues come to the forefront.

Lorena, Texas (South of Waco)