Distributorless Ignition System PDF Print E-mail
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The Prototype
Written by Nick Williams   

Update your Corvair's ignition system with EDIS!

The benefits of this conversion are:


1. Elimination of any timing scatter, which will allow you to run a better advance curve. All distributors have timing scatter, just use a timing light to see it. Points based distributors might not even fire every single time; EDIS hits every time, and it's always dead nuts accurate. Result- possibly more power. For sure my Vair runs much cooler, thanks to the addition of 'vacuum advance'. The old turbo distributor only had mech advance and pressure retard, resulting in an overly retarded spark at cruise. Now, it runs around 350*F, where before it was hovering around 400*F on the dash gauge. Being programmable, you can map out any ignition knock when you notice it. It's completely tailorable to your particular setup.


2. Nice hot spark. EDIS has a hell of a kick to it, ask me how I know.... Plus since it has 3 coils vice 1, the coils fire less often. It doesn't have to work as hard to produce good strong sparks every time- Each coil fires a third as often as a stock coil would.

3. Never buy points/rotors/condensers/caps/wires ever again! on a long enough timeline, it pays for itself just because of the tune up parts you no longer have to buy.

4. Reliability. Since you're using OEM parts (Megajolt box excluded-it doesn't have any load on it) for the conversion, you don't suffer any undue loss of system reliability. I'd say you gain reliability over a points distributor.

5. It's cool! Most people don't even know what it is, so you get to explain to people at shows how your old car has modern technology blended into it to make it better. I have a neighbor who nearly lost his mind looking for my distributor! Smile

 

 

 

 

OK ladies and Gents, I promised this for a long while so here it is.

This is my example of how to do it, not the only way. Somebody somewhere has made a better looking bracket, or some other part that you might rather use, but I'm a tightwad-therefore I made everything myself. For example, you might want to use American Pi's dizzy blank off/oil pump drive pictured here: [www.american-pi.com]

Let's get started.

First you need to scrounge up all the parts that make up the coversion, which are the following:
(FROM DONOR CAR)
1 Crank angle (VR) Sensor
1 reluctor wheel (36 minus 1 tooth)
1 6-cylinder coil pack
1 EDIS Module
Associated wiring, to include the connectors for the sensor, coil, and control module. These parts shouldn't cost you more than $150 at the junkyard.

From Autosport Labs:
1 Megajolt kit

About $100.
Total= around $250, depending on how well you know your junk dealer.

There are 2 ways Megajolt can do load sensing, either TPS or Manifold Pressure-not both. If you have a turbo engine, you MUST use MAP sensing, because TPS doesn't know how much boost pressure the engine sees.

Once you get everything together, the first thing to do is index the crank angle sensor, and mount it on the crank dampener/pulley. I did this by machining an aluminum plate, which mounts to the dampener via the 2 bolt holes that the puller screws into:



 

 

The toothed wheel must be indexed so that when the crankshaft is at TDC on #1 cylinder, the missing tooth leads the sensor by 60 degrees in the direction of rotation (each tooth is 10 degrees, so 6 teeth). Basically, you put the sensor wherever is easiest, and with the crank at TDC, you position the wheel with the missing tooth 6 teeth ahead of the sensor.
Some additional info: [www.bgsoflex.com]

 

 

 

 

 

After you get the sensor sorted out, the next thing is figuring out where to mount the EDIS module and Megajolt. I put the EDIS module next to the chassis ID tag, at the rear right-hand side of the engine compartment. Since my car has the vacuum/boost guage line, I decided to mount my Megajolt inside the passenger compartment, as it's not really weather sealed, and I had no idea how well it would stand up to the heat in the engine bay.

 

 

 

Since I have the 180 Turbo engine, I opted for the MAP load sensing option. I had already mounted a proper boost guage in the car, so I just tee'd into that line, and ran it to MJ.

 

 

 

 

Now, I ran wiring (plus a few extra wires, just in case of upgrades!) to connect the MJ unit to the EDIS control module in the engine compartment. This required popping off the tunnel cover, and routing some wires through there, up to the engine bay.

After everything's mounted, now you have to do the wiring!
This is the part where most people get lost (if you didn't already screw up the trigger wheel mounting, that is!). There are wiring diagrams at Autosport labs, and the Megasquirt sites for you to look at. One thing I strongly suggest, is using a high quality shielded line for the PIP and SAW signal wiring. These are the wires that send timing info to and from the Megajolt controller, and any interferance here will wreak havoc with your system. Make sure you use shielded cable on these 2 wires, you will regret it if you don't!

 

 

 

BTW, I can confirm as of today that the IDM wire (pin 2 on the EDIS module) will in fact power the Corvair tachymeter! I'm very happy about this, becuase I wasn't sure if the IDM pin could power the tach on it's own. Trust me, it works. Simply wire pin 2 from the EDIS module to your old tach wire, and presto!

OK, by now you should have the wiring done, and everything mounted. Now, you have to make sure that you're getting the ignition to trigger. This is easiest to do the same old way it's always done- pull a spark plug wire, stick a plug in it, and look for a spark during cranking. You don't need power to Megajolt to check this- EDIS has a limp home mode, set to deliver 10 degrees advance with no input. So really, as long as you got the trigger wheel mounted and indexed correctly, the EDIS module has power, and the firing order is correct, the thing should run.

After you've verified it runs, next thing is to hook up MJ, get it to control the timing, and use the timing light to verify it is in fact providing the user specified advance. You program advance tables into MJ using your laptop. Don't forget to save your changes often, because if you lose power, you lose your progress!Here's where I mounted my coil pack; it occupies the space that was formally taken up by the distributor.

 

 

 

 

 

I found out that the trigger wheel cuases interferance with the oil filter when installed, making it necessary to use the 90 degree adapter.

 

 

 

 

Here's a close up of the distributor plug I machined. Basically, I took a piece of pipe, machined it down so it fits in the distributor hole in the block, and welded a cap to the end of it. Next I took another pipe and machined it down, so that it fit the distributor shaft, and the previously mentioned piece. Basically, it's 2 pipes machined so as to support the shaft radially. Axial play is controlled by machining the depth of the second pipe piece, so it rests upon the OEM thrust washer. I'll post pics of the guts if you want. Here's a close up.

 

 

 

 

Here's a pic of the underside of the pulley/crank sensor.

 

 

 

 

 

 

**  A special thank you to Nick Williams for allowing us to post this wonderful article.  If you would like to contact Nick, you can reach him by email:  This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 
Last Updated on Friday, 22 January 2010 16:01
 

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