Dan said, > "I had a GPASC 2180 back before they realized that the oversized valves were useless and a detriment. The replacements that I got from GPASC, were from EMPI"
The ones I have are also EMPI. There's some discussion about the value of going to the 40mm valves - my position on the issue is that the larger valve helps dissipate and distribute heat. Excess heat is at the root of all VW problems pretty much, so anything that can help dissipate heat is good. Bob Hoover's essays on the subject are worth their weight in gold. If the VW is run cool the chugger will chug along forever. When Steve put this engine in he ran it everywhere he went at 2900 RPM. I run it between 3100-3200 WOT. Steve flew low with reduced throttle. I fly high with a coarsely-pitched prop. The point is anything higher than these RPM's generates a huge amount of heat from internal friction. High RPM's is what causes the heat problems. Running it slow and easy keeps it cool. Tommy said something about running it too lean. If that was done below 8000 feet where full throttle will produce more than 75% power, then yes, running it too lean in that situation can/will cause operational temps to be exceeded and can cause case cracks, head cracks, failed valves, and who knows what else. The VW doesn't put up with consistent overheating. Once in a while - climbing out on a hot day fully loaded, it will tolerate it when these occasional situations arise. Running rich in such a situation is necessary, not for proper combustion, but to keep the engine cool. Above 8000, or if at 75% power or less when below 8000 (non-turboed), there's nothing that can be done with the mixture that will harm the engine in any fashion. Except for situations where the excess fuel is needed for cooling (take-off and climb-out on hot days) lean is good. The leaner the better. Some will remember I had a valve spring failure and forced landing when over the top of the TCA in Tampa some years back. When I got it back home to San Diego I took the heads off and not only put new German springs in but also used Langford's world-class tutorial on head work to re-do my heads. I cut new seats with the Neway cutters like Mark recommended and put new Manley valves in, same size it came with. 40mm and 35.5. At the time I took the pictures at the link below those heads had 753 hours on them. As you can see, there's no cracking and I don't expect there ever will be any. The EMPI heads that Steve used in building this engine have been great. If he or RIMCO had not put re-used exhaust valve springs in when putting the heads together I wouldn't have had my spring failure - however that event provided a good opportunity to clean up the heads and put some bulletproof valves in. After 753 hours you can see in the pictures the guides were still like new. That was thanks to Steve putting swivel feet on the rocker arms and also because the guides were put in straight to start with. Mark has mentioned Jim Hill's engine, also from GP, which didn't have them put in straight - at least on one of them. It caused endless problems. https://goo.gl/f7ijlu Mike KSEE ____________________________________________________________ nowbuzzing Horsing Around: Insane Photos of Ideas Gone Wrong http://thirdpartyoffers.juno.com/TGL3141/571bd9e944def59e708bcst04vuc
