[Top] [All Lists]

Re: Roller Rockers & cam failure

Subject: Re: Roller Rockers & cam failure
From: "Jack W. Drews" <>
Date: Thu, 09 Feb 2006 11:53:02 -0600
I purchased a set of roller rockers, standard ratio,  and installed 
them on my race engine. I subsequently removed them and gave them away.

Let me say up front that I screwed up installing them. Since my 
standard rockers contacted the valve stem properly, I did not give 
enough care to checking them.

I seized some valves in some guides, trashing an engine. Subsequently 
I found that my trusted machine shop had not given me enough 
clearance on my bronze guides, but during the rebuild I discovered 
that the roller contact patch was not centered up on the valve stem, 
so then rightly or wrongly I blamed some of the valve guide sticking 
problem on the roller rockers too.

During this whole process I read everything I could lay my hands on 
regarding roller rockers. What I learned was that centering them up 
is sometimes a snap and sometimes nearly impossible. In the final 
analysis on my engine, the valve stem protrusion above the head was 
greater than stock (trying to use up that head) and there was nothing 
I could do to center up the contact patch. And no, shimming up the 
stands doesn't correct it. When I installed them on another head with 
different valve stem protrusion, the geometry was okay.

If you'd like to read some really interesting stuff on this, take a look at and look at the links 
referring to mid-lift.

===  unsubscribe/change address requests to

<Prev in Thread] Current Thread [Next in Thread>