cam sensor only setup for Ford 302 ?

[rickster]

I am in the planning stages of putting together a Ford 302 motor (actually a vintage 289 block bored/stroked to 306) with wasted spark ignition and EFI via MegaSquirt 2 w/ v 3.0 board. I already have 2 MS modules that I got from a friend of mine who quit the racing business, and have the engine pieced together except for the motor speed sensor input. The late model Ford small block uses a cam hole plug that in turn houses a spindle and gear assembly to turn the oil pump. This piece is readily available and retrofits to all small block models. The end of this shaft is can be exposed by removing a cover plate. The late model EFI small blocks also use this hole plug as a cam speed sensor for sequential EFI.

My plan is to modify what appears to be a single pulse vane type hall effect setup to a 24/1 wheel and sensor. This would eliminate the need to add a crank wheel, and would keep the EFI setup somewhat hidden.
I'm having a hard time wrapping my head around what type of wheel/sensor combination I would need for this. The cam turns 1/2 speed vs the traditional crank wheel, so would I need to find a 50 tooth gear and remove 2 opposing teeth? Would a hall effect sensor be accurate enough at high RPM to accurately signal a gear with small teeth like that? The gear would be approximately 1" in diameter...

I have a small machine shop at my disposal, so I should be able to precisely align the gear to the end of the oil pump shaft (this turns in tandem with the cam via a right angle gear). Then integrate something like this (http://www.allegromicro.com/en/Products ... /index.asp) to read the gear?

Would this work well? and what am I missing?

Thanks in advance!

[trakkies]

I'm curious as to why you want to do things this way and use wasted spark? The beauty of wasted spark is it only needs a crank sensor. If you provide a cam one the need for wasted spark disappears.
There are disadvantages over using a cam driven sensor - the drive to the cam will introduce errors relative to the true crank position.
If for whatever reason you don't want to have a sensor on the front of the crank, it would be possible to fit one at the flywheel end with the engine out of the car. With considerable work.

[Matt Cramer]

You might want to have a look at the AEM EPM - it's a similar idea (and, for that matter, if it fits your budget, they're available for Ford 302s).

[fury fan]

Why not just use an EEC-IV dizzy from a 5.0 engine? They have a bad rep for poor reliability of the TFI ignition module, but it became remote-mounted on trucks and vans. Either way, you’re looking at installing a Hall sensor in the dizzy, the EEC-IV dizzy already has one in it.

[Matt Cramer]

Why not just use an EEC-IV dizzy from a 5.0 engine? They have a bad rep for poor reliability of the TFI ignition module, but it became remote-mounted on trucks and vans. Either way, you’re looking at installing a Hall sensor in the dizzy, the EEC-IV dizzy already has one in it.

Current code does not support signature PIP cylinder identification, and the OP was looking to run wasted spark.