phil brookman wrote: >>are the exhaust valves the limiting factor in the vw i ask this after >>reading bob hoovers accounts on the subject and he is adament that the >>exhaust valves get to hot when in continuous use at high rpm .i hear >>2900 -3000 or around 55-60hp continuous being the maximum <<
I don't claim to be a VW valve expert, but I can tell you that the 140 hp Corvair heads, which have much larger exhaust valves than the 110 heads, are famous for dropping exhaust seats. This is because the amount of aluminum is greatly reduced between the intake and exhaust valve, and the temperature delta is very large over a very short distance, which leads to relaxation of the material holding the seat (or even cracking), and the exhaust seats falling out. I think I'd leave the seats and size alone, but use Manley stainless valves and keep them adjusted. Slightly larger may be OK (that's what I have in my Ghia), but I wouldn't go to a lot of expense on the hunch that it would increase reliability... Mark Langford, Harvest, AL see homebuilt airplane at http://www.N56ML.com email to N56ML "at" hiwaay.net
