[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]
<x-charset iso-8859-1>Chromoly push rods expand about half as much as stock alum. PRs. I know, I tested them in my oven and used my 12" dial calipers. Alum @ 200F grew .016", CM @ 200 only grew .008". Same length push rods. Tom Tom's Old VW Home http://home.att.net/~drsowatt/index.html ----- Original Message ----- From: "Hal Sullivan" <tristessa@pon.net> To: <type3@vwtype3.org> Sent: Tuesday, November 06, 2001 10:37 PM Subject: [T3] Further research and experimenting material! > At 08:32 PM 11/6/01 -0600, Jim Adney wrote: > >The way I see it, however, the biggest contribution comes from the > >differental thermal expansion of the various parts and the fact that > >the cylinders and head studs are steel while the pushrods are > >aluminum (which expands 3x as much as steel.) > > Now *this* I want to check out. I'm using chromoly pushrods in one of my > aircooled VWs -- I'm going to have to start measuring my valve lash both > cold and hot, keep a chart of what I find. > > I've heard theories that the reason for the valve clearance is due to the > different expansion rate of the aluminum pushrods relative to the rest of > the engine. Following that theory, chromoly pushrods should expand at the > same rate (or nearly so). If that's the case, would the 004/.006 clearance > be as necessary in engines that use chromoly pushrods? > > ------------------------------------------------------------------- > Search old messages on the Web! Visit http://www.vwtype3.org/list/ > </x-charset>