Another way to check the tappet clearances is set them slightly loose cold, run the engine for about 20 minutes after the heat indicator on dash shows normal running temperature. Valve tappet clearance should be adjusted with the aid of a vacuum gauge. With warm engine idling saturate valve stem and guides with penetrating oil. Watch vacuum gauge while inserting a 0.002" feeler stock between stem and rocker arm noting the vacuum reading. If the 0.002 " feeler causes the needle to fluctuate, increase clearance until needle is steady. If no change in reading tighten clearance. Repeat till all are the same.
