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Re: Roller Rockers and Tappet Noise

To: Jeff Boatright <jboatri@emory.edu>
Subject: Re: Roller Rockers and Tappet Noise
From: Ulix Goettsch <ulix@u.washington.edu>
Date: Mon, 20 Dec 1999 15:33:00 -0800
Cc: Brian Doody <Brian.Doody@digital.com>, spridgets@autox.team.net
References: <C45048E5BA68D011ACE708002BE623F2031FAD58@ilo-exc-1.ilo.dec.com> <v0421010ab4843065c2f6@[163.246.48.154]>
Reply-to: Ulix Goettsch <ulix@u.washington.edu>
Sender: owner-spridgets@autox.team.net
Valve noise might be increased by the 1.5 ratio rockers.  They open
wider in the same time, so the valve action happens faster.  I have a
cam in my X1/9 that has short seat-to-seat duration, but opens the
valves very fast.  This gives performance while minimizing torque loss. 
It makes a lot of noise though...

Ulix

Jeff Boatright wrote:
> 
> I think that loud tapping after the gap is set correctly may be
> indicative of collapsed tappets or worn pushrods. I can't swear to
> this, but either the Haynes or Bentley (BL/BMC) workshop manuals
> state something to this effect in the sectoin on how to set the gap.
> 
> However, given that you've just changed the set-up, could it be that
> the rollers themselves are louder?
> 
> At 10:39 AM +0000 12/20/99, Brian Doody wrote:
> >Midget & Sprite Club - http://www.mgcars.org.uk/midgetspriteclub
> >
> >Folks,
> >
> >While on the subject of roller rockers
> >I have just fitted a 1.5 set to my '67 Sprite 1275
> >its also got a new Kent 266 cam + followers + new Mini Sports stage 2
> >unleaded head.
> >
> >I had a lot of trouble with the rockers hitting the rocker cover
> >but thats sorted now.
> >
> >HOwever AT the recommended TAPPET gap of .016" (.40mm) the valver clatter
> >is very loud - it doesnt sound right - is this normal??
> >Ive re-adjusted them over and over but to no avail
> >the car is only used on the road and not abused - do I really need so big a
> >gap?
> >or is something else wearing ???
> >
> >regards,
> >Brian
> >
> >
> >______________________________________________________________________
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> 
> Jeffrey H. Boatright, PhD
> Assistant Professor, Emory Eye Center
> Senior Editor, Molecular Vision
> http://www.molvis.org/molvis
> Mailto:jboatri@emory.edu

-- 
    Ulix                                       __/__,__      ___/__|__
..............................................(_o____o_)....<_O_____O_/...
http://students.washington.edu/~ulix/         '67 Sprite     '74 X1/9

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