HEI ignition module

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70Duster340

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I read that it was a good idea to have a dedicated ground wire for the HEI module. I have the aluminum Edelbrock heads. Would it work OK to run a ground wire from the module to the back of the cylinder head? There's a few bolt holes back there that I could attach it to.

Thanks!
 
Thanks. I wasn't sure how good of a ground the cylinder head would be, being that it has a gasket between the head and the block.
 
You are overthinking. There is no possible way that heads will be ungrounded, what with "several intake bolts connecting the manifold to the heads, and "more than several" head bolts. ANY bolt/ screw into the intake will be more than enough, the coil mounting, the throttle bracket, etc
 
no14 would be "oodles". It's only a few amps. now, it is better that it be somewhat close to the coil, IE don't put the module on one far corner of the bay, and the coil on the other.
 
Well, the module is mounted on the distributor, and the coil is mounted on the intake manifold, on the passenger side. I will only need about 6 - 8" of wire to connect the module with the cylinder head.
 
You do not need a separate grd wire, as the module grounds to the dist body. The dist clamp is the ground source. Roughen the tabs/feet on the clamp so that they make good contact with the dist.
Mounting the coil on an engine is a baaad idea. Yes, I know OEMs did it [ for convenience/cost ]. The coil has copper windings, a very good conductor of heat. So the coil heats up, & so does the resistance of the copper windings, reducing coil output.
 
I believe if you used one of them aluminum adaptor/heat sinks to mount your module it will be fine. I just mounted mine to the firewall with an aluminum shield/heat sink on my race car and have had no problems at all.
 
You do not need a separate grd wire, as the module grounds to the dist body. The dist clamp is the ground source. Roughen the tabs/feet on the clamp so that they make good contact with the dist.
Mounting the coil on an engine is a baaad idea. Yes, I know OEMs did it [ for convenience/cost ]. The coil has copper windings, a very good conductor of heat. So the coil heats up, & so does the resistance of the copper windings, reducing coil output.

This is a two way street. Mounting the coil far far away from the ECU or breaker points IS ALSO a bad idea. other than the additional RFI/EMI radiation by the NEG coil wire, the long length of the wire between the "switch" and the coil, and the entire length of the return path can degrade spark performance This can get even more important with such things as CDI

On a SB, is a coil mounted above the engine on the firewall really going to run cooler? I don't know. Is the difference in temp between the two enough to materially affect copper resistance? The more important question might be "what are you going to do about it?" I guess you could mount the coil up on top of the cowling, or "chop it into" the cowl vent. A rainy day might bring it's own problems. The fact is a lot of this gets down to practicality

On a conventional "switched" or Kettering system, the coil + is normally bypassed. The radio cap on the coil + is the bypass. This helps keep the spark pattern intact, as the positive feed is now held to a "filtered" stable point, if you will

This leaves the coil - return. Let's say you maybe had the ECU mounted up under the dash, and the coil mounted way out front on the apron "for air flow". Maybe it's an B/RB so the dist is out there. Now you have 5-6' of wire or more between the ECU and the coil - That wire has inductance and can interact at high RPM causing unwanted affects on the spark pulse

On the other end of length, is the trigger cable length, which can be even more troublesome
 
Dart,
You seem to take many things out of context. Where to start. Have no idea which 5-6' wire you are talking about that has' inductance'. With a BB, I would mount the coil [ which I have done several times ] on the rad support/rt side inner guard...& that keeps the HT lead short. If the car has the factory ECU, it is probably mounted on the inner guard or f'wall & will likely have longer wires than a SB engine because of the front mounted dist on the BB.
Nobody said anything about mounting the coil 'far away'. A good place would be the f'wall or rad support, inner guard, depending on where the dist is. Canister coils use oil to cool them. Why mount them in the hottest place [ on the engine ] when they can be mounted in a cooler place???
You keep harping on about trigger cable length. There is no problem with the length as along as the precautions discussed previously are observed. Never have I seen in instructions for MSD or other brand CD boxes any reference to the max length of the p/up wires.
 
I'm using that as an example. If you cannot understand the concept I have no help for you. You on the other hand seem to like to pick at things

other than the additional RFI/EMI radiation by the NEG coil wire, the long length of the wire between the "switch" and the coil, and the entire length of the return path can degrade spark performance This can get even more important with such things as CDI

If you can't read the post and ascertain "which wires" I'm referring to, then read it again
 
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Yes, I 'pick' at things that are incorrect.
Oh, & I understand the concept...& far better than you do.
Of course long coil + & - wires will degrade spark performance, but it is a matter of degree. By making the wires a couple of feet longer so that the coil &/or ECU can be more conveniently mounted, the 'loss' of spark energy would be minimal & unlikely to be seen on anything but laboratory grade equipment...if seen at all.

The 5-6' of wire was your quote & I never proposed a mounting position that would require that length of coil wires. You mentioned inductance, but left out capacitance. If the wires were separated slightly, there would be NO inductance.
 
You do not need a separate grd wire, as the module grounds to the dist body. The dist clamp is the ground source. Roughen the tabs/feet on the clamp so that they make good contact with the dist.
Mounting the coil on an engine is a baaad idea. Yes, I know OEMs did it [ for convenience/cost ]. The coil has copper windings, a very good conductor of heat. So the coil heats up, & so does the resistance of the copper windings, reducing coil output.

I still run a separate ground wire. Humor me. The Chrysler distributor is SUPPOSED to have a gasket under the flange between the flange and block as well as the o-ring everybody is familiar with. The distributor gasket is FelPro #6464. Years ago, they used to come in all the main gasket sets. Some still do, but not many. So most people got accustomed to simply leaving them off. That gasket is supposed to be there. If it is, there's only the hold down bolt going into a possibly dirty hole in the block making that ground connection. Even if the gasket is missing, that's not a very good dedicated ground, IMO. It should have a separate ground wire. Just one old redneck's opinion of course. Take it as you will.
 
I still run a separate ground wire. Humor me. The Chrysler distributor is SUPPOSED to have a gasket under the flange between the flange and block as well as the o-ring everybody is familiar with. The distributor gasket is FelPro #6464. Years ago, they used to come in all the main gasket sets. Some still do, but not many. So most people got accustomed to simply leaving them off. That gasket is supposed to be there. If it is, there's only the hold down bolt going into a possibly dirty hole in the block making that ground connection. Even if the gasket is missing, that's not a very good dedicated ground, IMO. It should have a separate ground wire. Just one old redneck's opinion of course. Take it as you will.

NOTHING is ever hurt by extra ground wires. In addition to what you say, consider how good the ground is while adjusting the timing with a distributor mounted module. I'll keep the extra ground wire even though that wasn't likely my problem.
 
spark plugs need to be shell grounded to work and their ground is the cylinder head. Cant get much better than the head to ground to. None the less, I have seem plenty of drag cars run straps from both heads to chassis.
 
RRR,
Yep remember the dist gaskets, prior to the o ring. Still have a bunch hanging from the rafters....

Makes no difference. You do NOT need a separate grd wire for the above dist. If you roughen the feet on the clamp as I suggested [ & even this is probably overkill & not needed ], the dist grounds via the clamp & the bolt.
Look at the contact area of the main battery lead of a starter cable at the starter end. Commonly a 5/16" stud with a nut & lock washer. It does just fine passing several hundred amps; with the ign we are talking about less 10 amps!
 
You can never have too many grounds. Yes it's a good idea to ground the module as well as the alternator case. Braided ground straps are best.
Firewall to cyl head
module to strap mounting pt on the fire wall
alternator case to inner fender.
Battery to core support and engine.

Metal to metal contact is required at all pts, no paint
As far as the voltage drop discussion that is a bit of hot air as long as the wire is the correct size so size matters. Trunk mounted batteries come to mind with no voltage drop issues. Whats that volt meter set on - micro volts?
microvolt (plural microvolts)

  1. One millionth (10-6) of a volt, abbreviated as µV.
 
Well I certainly hope I didn't cause a major problem with the members here.

I made a short ground wire that runs from a machine screw that attaches the HEI module to the mount, and attached the other end to the back of the cylinder head. It's not going to be very noticeable when the engine is installed in the Duster. Certainly couldn't hurt.

As for the coil, it's a Mallory E-core coil that sits on the intake manifold at the stock location via a bracket that I purchased from Mancini Racing. It's close to the distributor, so the wires from the coil to the HEI module are only about 6 inches. The wires were made with heat shrink terminals, with 3 pieces of heat shrink tubing holding them together, and plastic wire conduit covering them from the coil to the HEI module. I did the same with the wires from the distributor to the HEI module.

The one thing I didn't do was coat the terminals with dielectric grease. I will do that at a later date.
 
I'm not sure dielectric grease is a huge deal. It's likely more useful in the HV tower. There's been a number of us use HEI modules, I've used them in about 3 projects. One was a Toyota 20R I swapped into a Cletrac crawler "red neck low budget" LOL

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Well, I posted this question as an informational guide, mostly for my sake (obviously). I certainly didn't mean to cause any ill will or hard feelings among members. I have always respected the information and/or opinions of the members here. I used to spend more time on another forum, but that one became a hassle due to snide comments from members who considered questions "stupid", and had no aversion to stating that opinion. Complaints to the forum owners went unanswered, so I left. Haven't been back there since. I always find what answers I am looking for here, and nobody belittles me in the process.
I just don't want to see this form go that route. You all seem like more of a family than anything else.
 
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