Maybe it is a combination of things.
- Too much oil pressure which rises the gear load
- high lift cams which don't continuously spin, they have a pulsing rotation
caused by valve and springs
- high revs which can cause resonances on the front part of the cam where
the gear sits
This could result in some kind of pitting that starts to end the story.
But very difficult to tell.
Chris
-----Urspr|ngliche Nachricht-----
Von: Tony Drews [mailto:tony@tonydrews.com]
Gesendet: Montag, 28. Mdrz 2011 18:45
An: MadMarx; fot@autox.team.net
Betreff: Re: [Fot] Distributor gear failure
Interesting theory. Jack did not have too much oil pressure when the
gear failed.
- Tony
At 11:37 AM 3/28/2011, MadMarx wrote:
>Could it be an oil pressure issue?
>When I installed the cam I also installed a new crank with a smaller
bearing
>clearance.
>The oil pressure was pretty good after that.
>Cold close 100 psi, hot around 85-90 psi.
>I didn't change the relive valve and ran that engine several races with
this
>high oil pressure.
>Maybe the gear failed from too much stress caused by the oil pump?
>
>Had Jack too much oil pressure?
>
>Chris
>
>
>-----Urspr|ngliche Nachricht-----
>Von: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] Im
>Auftrag von Larry Young
>Gesendet: Montag, 28. Mdrz 2011 18:19
>An: fot@autox.team.net
>Betreff: Re: [Fot] Distributor gear failure
>
>I have been watching this discussion with interest, because I would like
>to know if there is some gear alignment method I don't know about.
>
>I'm familiar with the failure that Jack had and do not believe it was
>due to a problem with the blank. Back in 2005, I purchased two blanks
>from the UK and had them ground. One went into my car and one into
>Jack's Mine never failed. Jack's failed immediately after he had
>another problem with a valve hitting the top of the cylinder liner. I
>believe the force of the impact was transmitted through the pushrods to
>the cam causing deflection and misalignment of the gears. This occurred
>at the 2006 gathering at Hallett.
>
>More recently I have gotten more than 20 blanks from Racestorations in
>the UK. Chris has had the only problem with a gear. The vendors, Moss,
>BPNW, etc., must sell large numbers of cams ground on new blanks, yet we
>don't hear of may gear failures.
>
>- Larry Young
>
>On 3/27/2011 4:07 PM, Kramer, Robert wrote:
> > Uncle Jack came to the conclusion that the aftermarket blanks had
>incorrectly hobbed gears for the distributor drive. I've stayed with
>regrounds ever since.
> >
> > Bob Kramer
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