Huh…that explained the “impact” version. I had no idea semi tractor lug nuts were 33mm.
You make several good points, Kirby.
The Electromotive (EM) system requires a 60(-2) tooth arrangement, but yes, I’m sure a 60-tooth motorcycle sprocket exists, just the same.
However, EM is fairly picky about the geometry of the teeth to ensure good clean timing signals. Since they’re roughly double the tooth pass frequency of most systems, I suppose the pickiness is justified?
Perhaps more to your point, though, EM does offer pre-machined timing wheels at reasonable (relative to what I have shown above) prices. The challenge on the Jaguar is that the wheel cannot flush mount to the back of the damper because then the original sensor mounting location can’t be used.
Defining a new sensor mount and location adds complexity and another point of adjustment, etc, etc. (It is reasonable to suggest that even a complex bracket would be less expensive than the machined wheel I have proposed, though.)
If the original crank position sensor location (6 o’clock) is going to be used, the teeth need to be around the profile of the harmonic balancer, but attached to the center hub of the balancer (see comments between Merek and me). Basically, I took the OE stamped steel 3-tooth wheel and turned it into a 60-2 tooth wheel, which resulted in the design you see above. I went with integration simplicity over cost effectiveness on my original design. I vary well may re-think this, since the timing wheel (at the current quoted price) would cost 2.5x the cost of the transmission, 1/2 the cost of the engine, or more than everything else I have purchased for the engine to-date, combine!
Drew when I made mine I machined the back off the double pulley and fabricated a disc to replace it, but this only worked for me because the car doesn’t have air-con and I could sacrifice that pulley position. I have seen a 1/8" 60-2 tooth wheel sandwiched between the pulleys and the damper, This seemed to work quite well. Both set ups need a fabricated sensor mount on the timing cover.
For my MegaSquirt setup on 71 SIII E Type I used a late model damper just for the reason that the existing trigger wheel location was located on the center section and would not be subject to any deviation in position, like if for some reason the outer pulleys had to be removed, etc. Here is what worked for me:
Tooth Pattern 60-2
OD 5.5″
Center Bore 2.82″ Diameter
Bolt Pattern 3 Slots on 3.46″ Diameter Circle 120 Degrees Apart
Offset Angle 30 Degrees
Slot Dimensions 0.25″ Wide – Length to give +30 Degrees and – 30 Degrees Adjustment
Maybe this will give you some ideas.
HTH