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Mount trigger wheel where distributor used to be?
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Post Mount trigger wheel where distributor used to be? 
First time post, please excuse my future ignorance...

I understand that to get this thing to work, you need a 36-1 wheel mounted on the crankshaft. Since I am interested in installing this to get rid of my distributor, I'll have a hand rotating shaft doing very little once the distributor is removed. Now, I know this is driven off the camshaft, so spins at 1/2 the RPM of the crankshaft/engine so would it be feasible to fit a small 72 toothed wheel (72-1?) where the distributor used to be, or would the Ford sensor not be able to cope with teeth that small?

The engine, in case anyone is interested, is a 4-cylinder 2.5L aircooled unit installed in my Steyr-Puch Pinzgauer. It's already got a module installed to get rid of the mechanical points, but I still suffer badly from condensation in the distributor and it's not easy to access to clean out. The vehicle runs on 24V, so I'd have to install a voltage dropper - how much power would the ECU and coilpack need?

Thanks in advance,

Robin

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Welcome to the forum spandit.

Check out http://www.autosportlabs.org/viewtopic.php?t=2026&postdays=0&postorder=asc&start=0 but you are definitely on the right lines.

It will cost a little more to have the trigger wheel manufactured (and more accurately). You can use different VR sensors which will hopefully look pick up better.

It would be better and probably easier (ie less tricky) to fit a crank mounted trigger wheel and sensor, but the choice is yours.

Love the vehicle by the way, you would definitely be the first to Jolt one of those!!!! and I would expect excellent results with it too as the MJLJ does give improved bottom end torque and is much smoother.

I'm pretty sure the system only runs 12V, not 24V. Power wise the system is quite electrically efficent. MJLJ way less then 0.5A, EDIS roughly the same but does sink some power from the coil, and the Coil pack itself probably around 5A.

A possible solution is an extra 12v (small) alternator and battery on a seperate circuit. Can't say I have dealt with 24V set ups much before.

Regards

Ryan


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Thanks for the reply. I think to try and run a separate 12V alternator would be more difficult than fitting a 36-1 to the crank (this guy has fitted one, he's running full EFI: )

I found this for a reasonable price:

http://www.bearingboys.co.uk/1_0_Mod_x_72_Tooth_Metric_Spur_Gear_In_Steel-67762-p

Thinking it would be easy to modify by grinding off two opposite teeth & I can bore out the centre in the lathe if required. The engine redlines at 4500rpm so we're not looking at massive speeds and from the post you quoted, it looks as if the Ford sensor can cope with smaller teeth. Think I'll order a system from trigger-wheels.com, unless I can find it cheaper on eBay

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So long as you do a bit of homework and you know what direction to take then go a head. You seem to know what you need.

Just note that there aren't too many 72-2 systems out there so you are in quite a lonely territory with this, but the people on this forum, I'm sure, will help/advise you where they can.

Get in touch with dean924 for advice prior to fitting the system . I'm sure he can give you some personal pointers he may of not written about and things to be aware of.

As a point of safety, it would be best if you could make arrangements for a guard or similar around the rotating disc. I'm not sure where your dizzy drive is but some can be easily accessible from under the bonnet (or whatever you may have) resulting in a lost digit or similar (check out my powered by post).

Do you use this for off roading or similar??

How are you planning to power it on your 24V system out of interest???


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As far as 24V, I would use two 12v batteries in series and just power the Megajolt from one of them. It doesn't draw much at all, 5 amps tops. Simple and effective. If you must use the distributor, others have had good luck using a Mazda rotary pickup from I think their distributor. Dean 924 can help with this or look for posts from him. His seems to work quite well. A trigger wheel on the crank is far more precise though and the Ford sensor is very robust.

I have had the system on my type1 for 3 years now, with a 6500 rpm limit on my 2165cc. It is the best mod I've done to the engine and really the whole car. Drivability is GREATLY increased, and it has also given me quicker starts and a rock-steady idle.

By the way, Pinzgauers are very cool!

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I'm intrigued by the 72 tooth spur gear you linked. I've been looking for one for a rotary application that is currently in the works.

Like others have already mentioned Dean924 has a bit of experience with a similar setup on his Porsche using a VR pick up form an RX7 distributor IIRC. He's had on going success with his. Mine will be similar but will incorporate both of the VR sensors in the 1st gen. RX-7 distributor. Is there a way for you to just use the 72 tooth gear in your factory distributor?


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Thanks for all the replies.

I'm not sure what the difference is between a crank sensor and a rotary sensor.

My logic is this: in a 36-1 system, for each engine rotation, the sensor will see 35 peaks then a gap. If I mount a 72-2 wheel to the distributor drive (basically in place of the rotor and yes, I'd make a housing for it - it would be completely sealed) then the sensor would see the same (I'll have a look at Dean's posts to see if I'm getting confused somewhere)

Regarding the 24V, I've been advised that taking a feed off the middle of the 2 batteries is a no-no but my voltage dropper can handle 15A so I could run it from that (although might buy another one)

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I for some reason just stumbled on this post. If you are still working on getting it sorted give me a shout. Going to a cam trigger with 72-2 really is not any more complicated than using a 36-1 on the crank. The reason for the sensor from an RX7 is two fold.

1. Size of the trigger wheel teeth. It can can sense smaller teeth. The teeth in the RX7 distributor are really small. I also remember some one using a piece of rod stock that had the 72 teeth in it that they cut to length and used in a distributor with an RX7 sensor (what got me thinking to use that sensor). The diameter of that wheel was probably about half the size of mine and it seemed to work well.

2. It works well with smaller diameter trigger wheels. If you read forward in my post noted above you will see that I had to take the sensor apart and assemble it to allow for a the bigger gear I was using. This lends it to being used inside distributors (where it came from in an rx7)

Lastly don't get all wrapped up in argument that you loose precision by going to a cam or distributor triggered system. Yes using the distributor will probably be the least accurate depending on how it is turned. My car has the distributor as part of the camshaft so the only chance of inaccuracy is caused by variances in the timing belt. If you use say a small block Chevy there crank turns a chain that turns the cam that then turns the distributor via a gear at the other end of the cam you will have a less precise system than had you just triggered from the crank. But ultimately it really should not matter especially for a street vehicle. Another thing to consider is that the inaccuracy or variances will be constant so you can tune for it. You can not do hat with the stock set ups.

What does all this mean? Not much really. For the most part but upgrading to an EDIS system is a huge improvement from the system that you are replacing. Voltage, reliability, multi spark at low rpm, and accuracy and reliability will all be improved not to mention that it gives you complete control of timing. So even if you retrofit the trigger to the stock distributor you will have an big improvement. Just make sure that all the bearings and gears are in good working order.

If you want more info I am glad to share PM me here or email me smith(at)radio(dot)fm.



Last edited by Dean924s on Tue Aug 23, 2011 4:51 pm; edited 1 time in total

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you can see pictures etc of my in-distributor installation here:

http://www.autosportlabs.org/viewtopic.php?t=1648

it uses the mazda RX7 sensor mentioned above, and a piece of 72 tooth gearstock which i bought online from the USA. then drillled by a machine shop for an interference fit to the distributor shaft, and pressed on. i ground two opposing teeth of with a a dremel.

mind you, it seems Spandit's haflinger is up and running since the original questions, so perhaps this is just for future explorers...

cheers,
alexander.

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Haflinger? Pinzgauer, my friend, the big one!

Pleased to report it's far better in the wet than the old system

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of course, i do apologise. what an utterly cool vehicle.

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Thanks! Fuel bill isn't too cool, mind you, don't know how much of a difference the MJLJ will make

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I know this is a late post, but for anyone searching the forum on a later occasion, here is another link on the subject:
http://www.autosportlabs.org/viewtopic.php?p=17163#17163


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alexander wrote:
you can see pictures etc of my in-distributor installation here:

http://www.autosportlabs.org/viewtopic.php?t=1648

it uses the mazda RX7 sensor mentioned above, and a piece of 72 tooth gearstock which i bought online from the USA. then drillled by a machine shop for an interference fit to the distributor shaft, and pressed on. i ground two opposing teeth of with a a dremel.

mind you, it seems Spandit's haflinger is up and running since the original questions, so perhaps this is just for future explorers...

cheers,
alexander.



I realize this post is quite dated, but does anyone have any idea where to find 72 tooth gear stock, in such a small diameter? The only thing I have found with 72 teeth was over 5".
I am trying to do pretty much the same thing as alexander, but inside a Mazda Miata CAS

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Have you checked here: http://trigger-wheels.com/store/index.html


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