Trigger Wheel

[topcatcustom]

Yep, I just said it- trigger wheel! Only the thought of trying to get my 82 year old distributor with 16 leads to work properly is enough to make me be considering going all modern!

I'll be using a RV8 auto flywheel, which has a 36-1 tooth ring on the back, it seems a shame not to use it as it could be a right pain getting a trigger wheel on the front pulley.

Question is- can I use it or is there a reason it will not work?

[ChrisJC]

I use the 36-1 triggerwheel (standard GEMS), with the standard sensor to drive a MegaJolt Lite Jr. No problems at all.

Chris.

[DaveEFI]

36-1 is probably the most common trigger arrangement as it's used by EDIS.

[crayefish]

Only the thought of trying to get my 82 year old distributor with 16 leads to work properly is enough to make me be considering going all modern!

V16 or twin spark? Either way sounds tasty

[topcatcustom]

Cool, so as long as I can mount a sensor right up close to the back of the flywheel it should be ok, can I use a ford item for EDIS ok? It may be tricky getting it in position, I assume it needs to be mounted with its back to the flywheel so it picks up the flats of the teeth, as they are folded 1.2mm or thereabouts?

Twin spark, could be a bastard!!

[DaveEFI]

If it's a Rover flywheel and trigger wheel, I'd mount the sensor in the same way Rover did.

Here's some light reading about EDIS and trigger position, etc.:-

http://www.msextra.com/doc/ms2extra/MS2-Extra_EDIS.htm

[topcatcustom]

I wasn't sure if the sensor had to be at a specific point on the trigger wheel at TDC, after a quick read of your page it looks like it needs to be 50° off, so I will bear this in mind when locating my flywheel!

I'm using a Rover flywheel and auto box, thats about it, machining an adapter to change the existing crank bolt pattern to a rover one, so I will have to drill the holes (one is offset) in the right place to put the missing tooth at the bottom, then the trigger will sit just to one side (by 5 teeth?!)

[stevieturbo]

How many cylinders ? 8 with two plugs or something ?

Some ecu's are more flexible with missing tooth position than others.

[topcatcustom]

Hi Stevie, yes 8 cylinders with 2 plugs, I'm planning on using megajolt as running carbs on this one. I may just rig it up as standard with one plug on each cylinder not used then can faf around with a piggyback system to fire the additional plugs later on once its running.

[DaveEFI]

If you're using EDIS, the fixed position relative to the missing tooth is required if you want the 'limp home' fixed 10 BTDC it provides if it looses communication with the engine ECU. But if you're simply using it as the trigger for the engine ECU which is also providing the sparks, you'd need to check with that maker how much tolerance it can have. With some, it can be anything.

[DaveEFI]

Hi Stevie, yes 8 cylinders with 2 plugs, I'm planning on using megajolt as running carbs on this one. I may just rig it up as standard with one plug on each cylinder not used then can faf around with a piggyback system to fire the additional plugs later on once its running.

Not an expert on Megajolt, but IIRC it uses EDIS, so will likely need the sensor positioned as for that.

Are you certain you'll never go injection? Because MegaSquirt can be used sparks only leaving the door open to change later to injection too - without having to start over.

[topcatcustom]

Going to stick to spark for now, keeping costs down too, though the EDIS 8 modules may be hard to pick up.

[DaveEFI]

Going to stick to spark for now, keeping costs down too, though the EDIS 8 modules may be hard to pick up.

Well, MS can do wasted spark by adding coil drivers, so no EDIS module needed. Not sure if Megajolt can.

But Trigger Wheels can supply used EDIS8 modules.

[stevieturbo]

What about a COP or Coil Near plug option ?

Buying the coils might be more expensive...but 16 HT leads is got to be messy !

Or with the right triggering system, you might be able to buy 8 twin output type coils and run them.

And strictly speaking, for wasted spark on an 8cyl, you actually only need 4 coil drivers.

Not sure of MJ could accommodate it though as it relies on using EDIS ?

A system that fires normal coils, or normal amplified coils might be more flexible as far as the physical coil installation goes.

[DaveEFI]

I'm not sure about using COP on an RV8 - they would get very hot due to the exhaust manifolds. Has anyone done it?

EDIS coils are cheap used as it's two 4 cylinder units for an 8, so plentiful. It's the EDIS8 module which is more expensive used due to having to be imported. But IMHO still the cheapest solution as so many have done it and all the fittings needed are readily available.

If building your own MS, a V3 comes with one coil driver. Additional ones (BIP 373) are about a tenner each and you'll need three for wasted spark.

Obviously if using one coil per plug you'll need 8 drivers - or coils with built in ignitors. In the US everyone seems to use LS1 coils as they are cheap and plentiful there - but not sure about here.

I'd say the cheapest option is EDIS with either MegaJolt or MS.

As regards EDIS plug leads I got used ones from a breakers and carefully removed the ends and fitted new cable to the correct length. Total cost under £25.