132 replies to this topic

[76lxhatch]

The module doesn't have to go in the distributor.

 

If you do want ECU controlled timing the 8 pin module is what you want, and can just be connected to any magnetic pickup distributor (this is what I did with mine):

http://www.megamanua.../GM_7pinHEI.htm

 

If you don't want ECU controlled timing then one of the other versions may be useful. All the GM stuff is pretty universal/flexible, seems like a shame to move the entire engine and replace the dizzy just for the internal module. These modules are quite small and generally still available brand new.

[axistr]

Thanks Jeff if its not to much trouble that might give me a starting point. I was told that the HEI cap was around 105mm but may depend on which brand of cap also. Being approximately 20mm larger than my Mallory dizzy would mean the absolute minimum I would need to move the motor forward would be 10mm. 

 

Thanks for the info 76lxhatch all good stuff, and it takes a few reads to digest it all. I am not right up to speed on late electronic distributors so some of this stuff still goes over my head. I was under the impression that the module needed to be inside the distributor, so if I can have it outside that changes the whole ball game. I didn't want to install a ignition box and worry about electrical interference and trying to hide another electrical item, but being so small it shouldn't be a drama.

 

This Mallory dizzy is my mechanical unit which isn't currently in the car, which I would need to lock out. In the Mallory manual they say you need a balist resister in the system, but I am not sure what they are trying to protect ? the module I suspect. I would think the pickup or coil would not need the lower voltage. The dizzy I currently have in the car is locked out but has a solid state base plate assembly, I could strip it out and use a magnetic pickup with a bit of buggering around.

 

Not sure which way to go now. The HEI dizzy's  are cheap to buy and on ebay local sellers have them listed at $79.00 but knowing very well they would be a Chinese produced product maybe a bit sketchy.

 

 

  

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[slr5640]

 In the Mallory manual they say you need a balist resister in the system, but I am not sure what they are trying to protect ? the module I suspect. I would think the pickup or coil would not need the lower voltage. 

yep....... if you hook it up to the full 12v it will fry the module.

i just did one and now have to buy a new one ...module that is ..

I didn't realize my system had the resister wire bypassed,,,

[axistr]

Thanks again, In the photos you can see where the drip rail and rubber spark plug lead boots are the closest point. I am not sure how tall the small cap HEI distributors are. When I measured from the lock down plate to the top of the cap I got roughly 120mm. if the HEI distributor is shorter I would have more room but I wouldn't be surprised if its actually taller. I took the measurement across the cap 20mm below the lead rubber boots.

 

slr5640 I thought that might be the case. continual 12v might cause the module to Bundy off. But can the reluctor/magnetic pick up handle the constant 12v supply ?  

 

 

 

 

 

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[76lxhatch]

If you can lock out the advance completely then you can use your existing dizzy with a GM 8 pin module and ECU control. The two wires that come off the little magnetic pickup are all you need, those go to the ignition module. The existing module inside the distributor (little half moon black box thing) can be disconnected or removed entirely. The distributor pickup becomes the crank angle sensor and the rotor and cap are still used to distribute spark but it doesn't do anything else. Coil and ECU plug in to the other two plugs on the module (looks like they're the same plugs as used on the TPI built-in version; its probably the exact same setup).

 

I managed to get mine to bolt to the distributor body itself but you can extend the two magnetic pickup wires and mount it somewhere else, just needs something for a bit of a heat sink.

I also see you have a heater tap installed, have not long done the same thing to keep cabin temps down!

[axistr]

Thanks lx76hatch, just checking that I have this all correct in my head, the pickup alternates from positive to negative so does the module supply 12v through the P & N terminals to the pickup or is it self generating power through the passing of the tooth. I need to know the pickup can handle constant voltage or is it just the Mallory module that is susceptible to damage if a balist resister isn't used. The GM 8pin module uses constant 12v just didn't want to fry the Mallory pickup if I convert the dizzy. Also I will need to phase in the rotor, did you phase yours in ? I read somewhere that you need to have the rotor approximately 10 degrees advanced when the reluctor tooth is lined up allowing for ECM timing advance. 

 

Yah I piggie backed the heater tap cable onto my original heater dash control so it is progressively opening. I had to do it this way because my A/C system blows through the original heater box from the top and not from the fire wall side, and partially through the heater core when in cool mode. When in heat mode the flap moves up and all of the air is pushed through the heater core.  The system works exceptionally well in hot or cold weather, in fact even on 40 deg days we never use the high fan speed for long.

[76lxhatch]

If you use an ignition module with an ECU then the Mallory module is not used - and yes the ballast resistor requirement depends on the module driving the coil so this is no longer necessary (pretty sure the GM stuff just directly fires a standard 12V HEI coil). Mine isn't actually driving the coil, its only triggering the MSD 6A, but whatever the module is capable of is what you can do.

 

You won't damage the pickup, its basically only used as an input sensor so is not seeing any load (they're quite robust anyway). As you say it outputs an AC sine wave, you can hook the wires up either way but you will end up with different timing, it needs to be the correct polarity to phase the rotor with the cap correctly. Pretty sure magnetic pickups don't use a power input, they just induce their own?

 

It would be worth checking the rotor phasing is OK beyond that for peace of mind, I did a basic check with the degree marks on the balancer and it was fine, though I did put a wider rotor tip on it just in case. If you have between say 10 degrees BTDC and 40 degrees BTDC then as long as its at the correct post at both of those marks (not in mid air and not pointing to a different post!) then you're fine. The module controls ignition timing until the ECU commands EST mode (usually during cranking) and is fixed at 10 degrees advance. You can tweak the ECU reference angle to alter this slightly if necessary but preferably not.

[axistr]

Thanks lx76hatch I had another good look ay my Mallory mechanical dizzy and the pickup has markings on the wires coming out of the pickup pos & neg  The pickup includes a permanent magnet so your right in saying it is self powering A/C current. Its all starting to make sense now, just took a while to sink in through my thick skull.   

 

Great Jeff much appreciated, Is the cap you measured a genuine GM HEI cap or an after market cap ? going by those measurements I would only need to move the engine forward 5mm being half of the diameter difference in the caps which is very achievable. If the overall height of the dizzy is 15mm lower than my Mallory it would fit under the drip rail and I wouldn't need to move the engine. I have looked on the net but can't find dimension's on the GM HEI caps or dizzy. I have two choices to consider. 

 

Thanks again guys for all your help Lenny.

[axistr]

Ok decided to go with option 1 and fit a Bosch HEI ignition module from a Nissan N14 pulsar only cost $34.00 new at trade discount.

Strip out the old Mallory dizzy and locked out the mechanical advance which was as easy as loosening two screws and moving the advance plate till it hit the stops, also removed the weights and springs.

 

Removed the vacuum advance canister and decided to make a bracket to cover the hole and at the same time something to mount the module to. I incorporated a few groves in the bracket to help dissipate any extra heat. The Mallory dizzy also has a dial in rotor indexing plate so it can be advanced or retarded + or - 45 degrease or basically any position you want to align the rotor. I bench set it at 28 degrease rotor advance but I should be able to move it in the car if I need any further minor adjustments. Gapped the reluctor @.010" job done.

 

I cut off the pickup sensor wires from the internal circuit board and run new wires to the Bosch module.

 

Thanks for the tips and help lx76hatch. 

 

phase 3 complete, just about got everything to start fitting the EFI system.

 

 

 

 

 

 

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[76lxhatch]

Nice idea on the mount, should make a good heat sink and still puts it in a logical place. Very handy that the distributor already caters for phase adjustments too.

 

Is the circuit board not removable?

[axistr]

lx76hatch, I left the circuit board in because the mounting bolts for the pickup sensor are swaged onto the circuit board plate and the extra 1/16" in height kept the sensor and reluctor at a better alignment. I welded the vacuum advance plate to the base plate which is fully adjustable. I could have ground half of the circuit board off I suppose, but is was just easier to leave it as it and doesn't serve any purpose now. 

 

   

[axistr]

I have been extra busy lately so I haven't had much time to get stuck into the hatch until this week. I stripped out the intake and carby and thought I might as well set all the lifters as she has done 11,000 km since I built the engine. Every thing looked brand new so on with the E,F.I gear. Check the dizzy phasing and on with the wiring. Time permitting hope to have it running some time next week. Then the fun begins, tuning it in. 

 

 

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[76lxhatch]

That was quick, blink and you miss it!

[axistr]

Ok time has come to boot it up and check all the electrical circuits. Cranked the engine over but don't have any ignition signal on the laptop with Holley virtual dash software. In the back of my mind if I was to have any issues with fitting EFI it was always going to be with the ignition side. Because I don't have an ignition signal the E.C.M  has no injection output either.

 

So I hope someone on here has more knowledge of electronic/HEI distributors than me. I first put a test light on the coil + side, 12v and also have 12v to the ignition module (8 pin HEI module). When I crank the engine the module should be in bypass mode and directly trigger the coil on the - side. I hooked up the LED test light to the coil trigger wire but no signal. I proceeded to check the magnetic pickup sensor which is showing a slight voltage when cranking. (digital test meter on A/C voltage), Looking through a few pages on the old web tells me that I should see an A/C voltage between .3 - 1.6 volts when cranking but doesn't explain much more. This figure would be from a GM HEI pickup coil and I have used a Mallory pickup coil. I get a rise in voltage .03-.04. I don't think I am testing it wrong, but at this low voltage I wouldn't think there would be enough energy to trigger the module.  I set the pickup coil gap to .010" which Mallory recommends.

 

Suggestions welcome. 

 

Lenny       

[myss427]

I had a issue of not having exactly 12 volts when cranking and had no signal to the coil, wasn't discovered until we put a jump pack on and straight away the car started. Found out the Edelbrock system needs 12 volts to work. Don't know if this is any useful info, but it was very frustrating to track down.

[76lxhatch]

Kind of hard to test a reluctor pickup properly with just a multimeter, cranking is probably moving it too fast for a digital meter too, maybe try just turning by hand? There's really not much that can go wrong with it though and voltage isn't important (it varies with rpm anyway), its the AC that matters, as long as it goes both positive and negative (i.e. passes 0V).

 

Sounds like you have it wired up right, there's a wiring diagram here (PDF linked in the second post) that's reasonably clear in case that helps?

https://pcmhacking.n....php?f=32&t=169

 

You will need a good +12V power source for it to work during cranking, normally the ignition system would use a relay rather than going through the ignition switch.

 

I would think your test light between a 12V source and the coil output would be the simplest test and should show something. Note that the ECU rpm signal is on a different pin though, you may be able to test that separately, not sure.

[axistr]

Thanks myss427 & 76lxhatch, I tested the pickup resistance going by Mallory's specks and checked out ok (185 ohms). I removed the cap and rechecked the reluctor gap and reduced it to .008" and got a slightly better voltage reading on the volt meter. With the ignition on I stuck a screwdriver between the pickup and reluctor and when I pulled it back out I had a nice blue spark that jumped 40mm. if I did the screwdriver trick repeatedly quick enough the noid light lit up which is connected to one of the injector plug so I have an injector pulse, the whole system is working. just not during cranking.

 

The coil and system has a 12v to it but dropped down to 10-10.5 volts during cranking I also checked the voltage at the battery and the reading are the same 10.5 so a relay wouldn't do me any good. I had the battery on a small charger last night and the engine seems to be cranking over quick enough. I have a 1200cca odyssey battery and high torque reduction starter. Its not uncommon for vehicles to drop down to 10.5 volts during cranking so I didn't see it as a problem. Because the Odyssey is a deep cycle battery I have put an old battery charger on with heaps of charging amps to insure I get the maximum into the battery and a second jumper battery and try it again later today and see if this makes any difference.      

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[myss427]

I also have the Odyssey small battery, and was also cranking in that zone. When we put the jumper pack on it gave us 12 volts and the car started. Also check that your plugs are clean, mine got too wet from trying to start it multiple times. I ended up putting one of the small capacitor jumper packs in the glove box wired through a cutout switch to boost starting, fixed the problem.

[axistr]

Ok something weird is happening, battery fully charged and also used a jumper battery, still pulls the battery voltage down to 10.5v during cranking ( I would have thought this was normal).

 

If I put the screwdriver on the pickup coil metal tap that the reluctor passes, and when I pull the screwdriver away it fires every time. If I wave the screwdriver past the metal pickup coil tab even as close as .005" it wont work. It seems that the metal screwdriver must touch the metal tab first then removing it causes the pulse needed to drive the module. Next I reversed the two wires from the pickup coil the module P&N terminals and now it only fires when I put the screwdriver onto the metal tab and wont fire when I take the screwdriver away so reversing the wires also reverses the screwdriver action, must be due the alternating current at least I know this part is correct.

 

  I also went around and checked with a test light, the dizzy, reluctor, dizzy shaft and pickup coil bracket are all grounded. The two wires from the pickup coil are not going to earth and have a resistance value or 185 ohms. I am not sure if the pickup coil bracket should go to ground or be insulated. 

 

Just had a brain wave half way through writing up the above findings.  Whent back out to the shed and got the Mrs to crank it over while I did the screwdriver action on the pickup coil and it produced a great spark. Bugger that may rule out the low voltage problem in the equation.

 

It just seams the reluctor passing by the pickup doesn't give it a good enough trigger and directly touching it with a screwdriver will. If the reluctor would lightly touch the pickup on the way past it would trigger it, but I can't do that without damaging things, so buggered if I know. Its properly something simple as insulating something just can't put my finger on it. Needs more trial & error tactics. I am just not proficient with electronic distributors which makes it just that little bit harder..       

[76lxhatch]

may rule out the low voltage problem in the equation

 

I would be inclined to agree with the above, its all or nothing so if its firing then you have enough.

 

Its not just something simple like a poor connection from the reluctor to the ignition module?