Back in '72 or '73 we were practicing on Saturday for a Can-Am race the next
day when a timing chain broke on our aluminum BBC. We pulled the engine and
hauled off it to George Bolthoff's shop where we helped tear it down and
scrounged through the shop to find parts that were good enough to replace
the broken ones-- all the speed shops were closed by then. We found
everything but a few Crane roller rocker arms but with the engine assembled
and missing a few rockers we went back to Riverside and the Shadow team was
kind enough to lend us the rockers that we needed to finish the engine. We
worked all night refitting the engine & tranny and made it to the starting
grid-- they actually held up the start of the race a few minutes so we could
take our place on the grid. The damn crowd was keeping us from getting out
on the track so Bob smoked the tires and scattered the people like quail.
The interesting thing was that our M8C McLaren finished and the Shadow
didn't.
Oh well-- just a story about broken timing chains from a non- sprint car
venue.
Regards, Neil Tucson, AZ
--------------------------------------------------
From: "Kirkwood" <saltfever@comcast.net>
Sent: Wednesday, May 26, 2010 2:33 PM
To: <land-speed@autox.team.net>
Subject: [Land-speed] Cam Gear Drives
> In the old days (after the flathead) the ubiquitous SBC was the engine of
> choice in circle track racing. That environment was a killer of stock
> timing
> chains. When a chain broke it was not a matter of simply replacing a
> $19.95
> chain. With a high compression motor a broken chain always resulted in a
> piston-to-valve collision! That $19 part turned into hundreds of dollars
> for
> repairs! When the $39 Cloyes roller came out it was supposed to be a fix.
> Not! The gear drive was created for durability in an abusive environment
> and nothing more. Regardless of advertising swill, I have not seen any
> good
> data clearly showing increased precision or efficiency over a roller
> chain.
> Although, engineering tests have shown precision gear systems may possibly
> have better efficiency that a chain it has never been demonstrated for
> currently manufactured timing gears.
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