Dwelling on VR & Hall sensors. Ignition upgrade paths.

[tob_007]

Hello all, an original v1 megasquirter here coming back a few years later for a bit more (MS still squirting great). I'm ready to ditch the points and go digital but getting a clean crank angle signal seems difficult.

The megajolt lite jr may be a bit too complicated for my needs. For my old classic vehicles and motorcycles: I would like to gain the digital ignition timing control capabilities but not necessarily go for the full Ford EDIS solution. I have 3 motorcycles and 2 cars with points and im really tired of fiddling. My MegaSquirted fuel injected land cruiser really demonstrates how quickly ignition points performance falls off between tune-ups. I would like to build one solution for my applications and keep my distributors, coils and wires etc...

Locked-in distributors with a nice VR sensor rising and falling with the distributor cam lobes would be a nice solution, but does this provide enough resolution for timing control? or does one need to go to the toothed wheel options for any kind of accurate timing advance strategy (rpm & map tables)?

Complicating the problem, the motorcycles have kick starts as well, I know VR sensors have a minimum speed threshold in which they will provide a good signal. As far as I understand it, slow speeds mean bigger diameter wheels to help out the VR sensor (ie major packaging problems for a motorcycle setup). What VR sensor seems to work well at slow speeds?

A Hall sensor setup would require building a shutter wheel but has the advantage that it can be very small and usually handles slower speeds better, im just not sure how much "dwell" (well what the ratio between open\close shutter openings) should be. A Wasted spark system on a twin cylinder would be a shutter wheel 180 degrees closed and 180 open? or 2 x 90 degree openings 180 degrees apart? like the bmw logo come to think of it!

Is there anything that is lighter\younger\simpler than megajolt lite jr??

As usual, all advice and suggestions are greatly appreciated!! Keep on mega(whatever)ing!

Toby
71 FJ40 land cruiser 6 cylinder (Megasquirted v1)
69 Austin Healey Sprite 4 cylinder
73 R75/5 BMW twin
75 R90s BMW twin
75 Honda CB 400 four (double points, oh the humanity)

PS wow the MS world has really moved! Microsquirt!!?? full assembled? where's the fun in that! Awesome to see so many more success stories!!

[Matt Cramer]

You can get pretty decent timing control with a distributor with a tooth per cylinder, although there are a couple engines where I've heard of hard starting issues. Maybe your best bet would be to start off with the basic distributor, and if you don't like the way that behaves add a 36-1 wheel, which could be a stepping stone to EDIS as well. Usually resolution is more of an issue when the engine is cranking than any other time.

[tob_007]

Does "tooth per cylinder" the same as lobe per cylinder? Can VR sensors pick up on the original points cam?

[Matt Cramer]

While more or less the same thing, I would not try running a VR sensor on a points cam.

[arnold]

Hi Toby

What route is it gonna be? I use the Crane Fireball XR700 ign, but still am struggling. Maybe I should go another route