On Jul 20, 1:22 pm, Reggie wrote:
On Jul 20, 9:04 am, " wrote: VW Engine Wear Factors

The exhaust valves are the weak link in any air cooled Otto Cycle
engine using poppet valves.
************************************************* **********

Is there a larger diam stem, Porsche, valve, spring, keeper,guide
assy that could
be placed in the VW head ???

Or even hot rod "kiddie" (after market) stuff ......

Reggie

The Fuel Injected 1600 cc engines (Type I) produced after 1975 had
larger valve stems, 9mm vice the 8mm used up to that point. The valve
itself, however, was smaller, which reduced the valve seat area, which
governs heat transfer from the valve to the head. In other words, the
smalled seats in theory offset the benefit of the larger stems. It's
not clear that this combination gave any longer valve life, and these
heads and valves, while allegedly available, are pretty rare.

I have no personal experience with them.

Veeduber has discussed in his blog using ceramic coatings to increase
exhaust valve life. Lots of potential there. I'm building an engine
with coated pistons and valves but it hasn't even run yet, let alone
flown, let alone proven itself with hundreds of flight hours.