quote:Rule of Thumb on bronze gears is- change them when the ignition advance retards more than 3 degrees, or in any case after 3000 miles of use. Frequent inspections of the gear teeth might extend this duration a bit on street cars.
Change a bronze gear with every oil change, assuming you actually drive the car and don't just admire it as art in the garage.
Check out this info posted from Dan Jones regarding the Mallory Steel Distributor gear:
quote:Mallory steel distributor gear (Ford 351C Part Numbers 29420 and 29420PD
http://pantera.infopop.cc/eve/...=651102286#651102286
quote:We are using the Mallory steel alloy distributor gear on this engine since the Accel distributor supplied has a 0.490" shaft and the Crane gear is only available in 0.500" and 0.531". In any event, the Mallory gear looked good and showed no signs of wear.
http://pantera.infopop.cc/eve/...=302105095#302105095
Here's my own communication with Mallory about their steel distributor gear for the 351C:
Q) Will your Alloy Steel Distributor Gear work with my hydraulic roller cam?
A) Our alloy steel distributor gears will work with all core material except 8620-9310 steel where our bronze gear will be used. The 8620 steel with iron gear option will work with our alloy steel gears.
http://www.malloryperformance.com/Faqs.aspx
Q) Is your distributor gear #29420PD compatible with a steel roller cam? Is it actually steel, or a treated ductile iron? Thanks!
A) The 29420PD is harden steel, sometimes the 29420 is a better choice because it's not drilled all the way through. This way you line up the hole in the gear with the hole on the shaft and finish drilling through, it always lines up that way.