Hey all this is why I used to rebuild my VW in my sandrail every year and now since being converted to the R.S Hoover way of Do it right and maintain it. I have not needed an overhaul since 97. Thanks Wayne ----- Original Message ----- From: <veedu...@aol.com> To: <kr...@mylist.net> Sent: Wednesday, October 22, 2003 1:04 PM Subject: Re: KR>VW Engine Rockers
> In a message dated 10/22/03 12:12:01 PM Pacific Daylight Time, > n5...@hiwaay.net writes: > > > The shims are there to get the valve train geometry right. The "right" way > > to do it is to make custom pushrods the right length, but shims under the > > rocker stands will work within limits. > > ------------------------------------------------------------------ > > On the VW engine the valves are at an angle of 9.5 degrees. Depending on the > ratio of the rocker and the lift of the cam, to achieve proper valve train > geometry on a VW you may have to adjust both the tower height, the rocker arm > position (vertically) and the push-rod length, which provides maximum > transmission of lift 'around the corner' at only ONE particular length. This is easy to > illustrate in a classroom... or with lots of charts -- but difficult to get > across via email without getting into trig The shims you found on the old > heads are going to be relative to the length of the valves and the wear (if any) > of your rockers, plus the assumption that you're using the same type of > adjusters. The length of the push-rods is going to be relative to all of the ABOVE > plus the width of the engine (actually, the distance from the centerline of the > camshaft to the centerline of EACH rocker-shaft [so don't get the banks mixed > up; they could be of different length]. > > All of which assumes your new heads are identical to your old heads, right > down to the freckles on their fanny. If not, you gotta start over again, set up > the valve train geometry from scratch. Or do like most engine builders and > simply ignore it. > > No big deal. Get your valve train geometry wrong you only give away up to > 20% of your power. :-) > > (Chorus: 'THAT CAN'T BE RIGHT! THAT CAN'T BE RIGHT!' ) > > (From the Conventional Wisdom Opera, Act II) > > -R.S.Hoover > > PS - Actually, a 20% hit would be the Worse-Case. But the typical dune buggy > engine gives away a solid 10% of its potential output. There's even room for > improvement in a crate engine from the Puebla plant, thanks to the normal > manufacturing tolerances. Find a Formula V race-engine builder, rattle his cage, > get ready to be impressed with some serious attention to detail. > _______________________________________________ > see KRnet list details at http://www.krnet.org/instructions.html >
