I think the most common gear failure comes from not having the distributor
tower clearance set. I destroyed a cam that way. Replaced the tower with an
aluminum one and didn't get the clearance right. Applies too much drag to the
shaft. You would think this gear engagement would be a lot more critical since
it drives the oil pump, which takes a lot of power, but in high mileage street
engines I've dismantled the cam and distributor gear always look fine. I think
the power demand of the pump must not be that much different in a street car
since all a race car needs for the weak drive connection to survive is
removing the stress risers in the slot.
On Mar 28, 2011, at 6:19 AM, Larry Young wrote:
> 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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Bill Babcock
billb@bnj.com
503.936.7660
www.bnj.com
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