QUOTE(CHAFF @ Feb 26 2007, 08:19 PM)
But here is the question no one wants to answer....you still need to shim up the mounting block? If so then doesn't the old push rod become too short hence you need a new set of longer pushrods?
It will work if you don't put any shims between the rocker shaft and the head. However, the rocker arms will not line up very well with the valves, which will lead to accelerated wear. Since one of the main reasons to do this mod is to cut down on the wear on your valves and valve guides, having mis-aligned adjusters is rather counterproductive.
To get everything set up "perfectly" (or at least close!), you need to set up some measuring jigs and fiddle with at least two measurements that I can think of off the top of my head. One is how far away from the head the rocker shaft is, and that's where the shims come in. Another is the pushrod length--which is where an adjustable pushrod comes in handy. You also, at least sometimes, need to mess a little more with the part of the rocker closest to the valve.
Google "rocker arm geometry" and you can probably dig up a few articles about the subject. Or head over to Jake's to read about the application specifically to the Type IV engine with swivel-foot adjusting lugs.
--DD