Following a timing chain failure during competition that resulted in a bent valve. Development began on a gear train to drive the overhead cams instead. Various bevel and spur gear drives were considered. The final design was the simplest featuring only three gears, a 2.5’ pitch diameter 25 tooth pinion on the crank and two 5’ pitch diameter 50 tooth gears, one on the cam and the other an idler. The purpose of the idler is to ensure that the crank and camshaft spin in the same direction, as with the timing chain, and to bridge the almost 9’ span between the crank and OH cam centers. The idler is mounted on a slotted plate that bolts to the crankcase, the plate and idler can be rotated about the axis of the crank such that the pinions and idler are always properly meshed. This allows different cylinder heads or compression ratios to be experimented with without changing the gear train.