Thread: tappet adjustment 350

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This is a great thread for me with two new ideas, namely setting valves when hot and the idea of holes in old valve covers to prevent oil spray. I recall studies/papers on setting the valves on 1300-1600 VW flat fours with mechanical lifters that showed that setting the valves close to the limits (tight) when hot produced about three more H.P. and recently I have seen comments on other sites that one can set the hydraulic lifters close to the tight limit so as to get the maximum duration of a given cam. However those articles said to gain a few added H.P. to only tighten the nut 1/4 turn, but this would require more frequent adjustments. I don't understand in the sense that if one tightens to 3/4 turns after contact of the lifter I would think that is TIGHTER and more likely to follow the cam profile more closely????? Anyway I guess after reading that I would compromise with 1/2 a turn while hot. Have there been any proven H.P. gains based on the 1/4, 1/2, 3/4 turns idea which is the optimum, 1/4 or 3/4 turns (hot)?? On the VW flat four there is little use for a hydraulic lifter with a horizontal lifter orientation in which the oil would form a bubble so they use a mechanical lifter, but I guess there is some "convenience" in the vertical (45 degrees anyway) orientation of the V8 lifters, assuming you keep the shiny side up! Thanks for the idea of the holes in the cover, I am learning a lot from this site! Streets and Tech1 and others really can comment on a lot of important little tips that might take years to learn on my own.

Don Shillady
Retired Scientist/teen rodder