Thanks for the replies so far. Let me clarify the situation.
I've got about 7 race motors... in various piston/cylinder head/cc's
configurations (and various stages of assembly, or disassembly). All are
either 948 or 998 (various bores up to .040).
This particular motor is one of 3 that came with a race car purchase. The
motor was assembled, and complete, with the head on it, flywheel, clutch,
etc. This was a car that had a considerable amount of documented race
history, and went to the Nationals numerous times.
NOTHING is known about this motor, other than the obvious that was
discovered when I tore it down. It is a .40 over, 948. Venolia pistons,
nitride crank, well prepared head. The cam (Moon, how cool is that?) was
toast... but the motor itself seemed fairly fresh. So, maybe it wiped a cam
and was pulled+ Dunno. Oddly, it was built with pistons designed to be proud
of the deck, but built considerably lower than flush.
We decked it .80 and skimmed .020 from the head to achieve 13:1 CR.
We're talking about STOCK rockers here. Not roller rockers. Not 1.5 ratio
rockers. Stock rocker assembly.
On the north/south portion, shimming the pedestal helped, but then the
adjusters weren't long enough/pushrods too long . These are the short, Crane
or Isky style tubular pushrod, that are already "short" by design. I ended
up heated up the pushrod end, removing the tip (they're pressed in) and
turning them down about .110 on a lathe and reassembling. That gave me
acceptable geometry.
So, the north/south portion is fine.
It's the east/west that is still f'd up. They are not lined up well on the
valve, and the hold some of the pushrods way off center. The only thing I
can figure is this particular rocker assembly, which I got from Hopper, was
already shimmed side to side for some other reason? Ron? Hmmm??
I've got a Copper S assembly I'll try this AM, and also some late model
rockers I'll also try. I've never seen the need for changing east/west
spacing on a stock assembly. Have you?
WST
-----Original Message-----
From: Hal Faulkner [mailto:hal@katemuir.com]
Sent: Monday, May 28, 2007 2:46 AM
To: Wm. Severin Thompson; spridgets@autox.team.net
Subject: RE: rocker spacing
Flounder wrote:
"Ever have to shim the rockers east/west to center the rockers over the
valve
and pushrod?"
If the ratios aren't standard (i.e., changing from 1.3 to 1.5) and you are
using the stock pillars you may find that they must be adjusted in order to
line up. I think the Mini Spares kits come with pillars that are designed
to avoid this problem and a hardened shaft. I'll let you know when I get
that far. Vizard mentions this somewhere in one of the chapters of the
yellow book.
Hal
|