Part: Valve Lapping / Grinding Compound (Coarse and Fine grit)
Why You Need This: Valve Grinding Compound, also called Valve Lapping Compound, is used to lightly sand the contact surfaces between the engine valves and their respective valve seats. Whether you are replacing your engine valves with new ones or cleaning up used originals that are within service limits, the seats where each valve sits will need to lapped to even out the sealing surfaces.
Since it is impossible to see how well a valve and seat fit together after years of wear make sure to pick up some Prussian Blue to check the consistency of the face contact the two parts make. This is done pre-lapping to determine the initial state of the parts and post-lapping to see if the lapping process was successful.
Sold as two .75 fl oz tubes, one coarse and one fine grade, one set of tubes will do several valve lapping jobs.
Our new "Airlock" valves are an excellent replacement for worn originals.
NOTE: Lapping can only correct minor imperfections in valve seats and sealing faces. If the seats, valve faces or guides are too worn, the head must be re-machined. Our cylinder head rebuild service can bring everything back to factory specifications.
Installation Tip: If you are replacing your engine valves then they must be lapped to the old seats in the head. Apply a thin coat of coarse to the valve face and press it into the seat. Use a valve lapping tool to spin the valve, lifting and rotating 1/4 turn between spinning. Remove the valve and wipe both the valve face and seat clean of valve grinding compound then apply a thin even coat of Prussian Blue to the valve face and press into head to see the progress. Thin, spotty or incomplete contact means the valve seats will need additional lapping or cutting to bring back them back to true. Take this process slowly and check your progress often. If you are close switch to the fine grit compound.
