timing belt

[larry leung]

Dynamic Interference is caused by the inertia of the valves, springs and Pistons (to a lesser degree, con rods, crank, etc.). The forces at high RPM's are so high (by a factor of the rotational rate + radius squared) that any tolerances come into play, certainly overcoming the static positioning of the valves and valve springs. 

LL - NY

------Original Message------
From: "Paul Heneghan" <paul at heneghan.co.uk>
To: Jonathan Vogel <jonathanvogel at home.com>
Sent: October 7, 2000 1:07:34 AM GMT
Subject: RE: timing belt


The experts on this group seem to be of the opinion that some engines are
static interference (i.e. if the crank is turned by hand while the cam
remains stationary, then some pistons will hit some valves.  The other
engines have gained the reputation of being dynamic interference engines (OK
if turned by hand, not OK if the cam belt goes at 6,000 rpm).  I'm not sure
what technical reasons are behind this theory - probably something to do
with the valve springs not being strong enough to accelerate the valves back
into the head at these sorts of speeds.

Paul
  -----Original Message-----
  From: Jonathan Vogel [mailto:jonathanvogel at home.com]
  Sent: 06 October 2000 02:46
  To: paul at heneghan.co.uk
  Subject: timing belt


  So I take it that all the 5 cylinder turbos are intererence engine.
  I'm only askin' cause I'm getting conflicting answers. I think I'll go
with your response, seems safer.

  Jonathan in Seattle