I was talking to a VW guy at Airventure and he mentioned that chromoly pushrods should be set to a “loose zero.” Basically meaning no lash but you can spin them easily when cold. He said that the original VW pushrods were aluminum which expand a lot, and the chromoly pushrods don’t expand nearly as much. The problem, he said, is when hot that 0.006” lash can grow to 0.018” and that is why people are breaking valve adjuster feet. If you have stock or aftermarket aluminum pushrods then use the 0.006”. I’ve never broken a foot but I did have a pushrod starting to unzip, as I documented on Sonexbuilders.
ery interesting.As things happened durring my break in period on my aerovee, when hot, valve lash was very tight, if non at all. I decided at that time (8hrsTT?) to add .002 in to the .006 spec. I have watched lash closely, and have not found a zero lash again when hot. I worried that any more than. 002 additional might be too much when cold. so far, so good, IMHO! I do not remember that my pushrods are aluminum, and I feel, without actually looking, they are steel, which came with the kit.
During the break-in period there is a lot of retorquing and valve adjustments as the motor settles in. My motor is broken in already, so I would not expect the valves to seat any deeper or anything. I guess one test is worth 1000 expert opinions - I’ll leave the safety wire off the valve covers and check the lash after my ground run. Thanks for the feedback SirPD! Also yeah the stock pushrods in the kit are steel.
