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Re: Rocker Arm Repair

To: RTriplett@bjservices.com
Subject: Re: Rocker Arm Repair
From: Drew Rogge <drew@pixar.com>
Date: Thu, 26 Apr 2001 07:53:02 -0700
Cc: triumphs@autox.team.net
Organization: Pixar Animation Studios
References: <OF6E837139.63BCFAB4-ON86256A3A.004BC759@bjservices.com>
>From what I saw when I took mine apart there are four areas of
wear; bottom side of rocker arm shaft (mine had pairs of huge
grooves where the rocker arms rock), bottom side of the bushing
in the rocker arms, tips of rocker arms which contact the valves
and the ball on the end of the adjustment screw.

The wear on the bottom of the shaft and bushings can be felt if
you back off the adjusting screw and try pulling the rocker arm
straight up and down. I have a second assembly and could detect
the play this way. It's kind of funny but there were significant
differences in the amount of wear on the individual rockers. I
can only assume that this is either from some rockers getting less
oil than others or from someone adjusting some of the valves tighter.

The sliding action of the rocker on the valve stem is what causes
the wear on the valve end of the rocker arm. This makes a groove
in the rocker that's a bit wider than the valve stem. The problem
this causes is that if you adjust the valve clearance with a feeler
gage, the gage ends up riding on the unworn parts on either side
of the groove and the valve clearence you get is the sum of the
feeler thickness and the depth of the groove. I don't know of a good
way of checking this besides removing the rocker assembly and looking.
I felt that the problem was pretty bad on my car and ended up setting
the valve clearence with a dial indicator instead of a feeler gage.

I don't know how to detect wear on the ball end of the adjusting
screw and frankly never considered that it would be a problem.
The only way I know about this is that the guy I talked to at RAS
said that it's one of the things they checked.

What Rocker Arm Specialist does is to grind the shaft down, hard
chrome plate back to oversize and then centerless grind it back to
the correct size. For the rocker arms they rebush to fit the shaft
and re-arc the ends that push on the valves. I don't know that they
do if they find bum adjusting screws. I could be wrong about this
but I'm pretty sure they do all this for around $87.00 but don't
quote me on that.

Drew

RTriplett@bjservices.com wrote:
> 
> >BTW, based on some recommendations I found on the web I decided to
> >send my rocker arm assembly to Rocker Arm Specialist to be rebuilt.
> >Had a bit of a problem contacting them though since their area
> >code has been changed from 916 to 530. Their current number is
> >530-378-1075.
> 
> Just wondering, what checks can be made of the rocker arm to tell if it
> needs rebuilding?
> Thanks,
> Richard Sr

-- 
Drew Rogge
drew@pixar.com

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