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HEI Ignition Conversion

Clemmons04

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I'm working on an 81 750K and trying to convert over to the HEI setup and I'm having a bit of trouble.

Another member here AMC49 has mentioned doing this multiple times but has never elaborated on the install. I DM him but he doesn't seem active any longer. If anyone on here has done this conversion and know what my voltages are supposed to be and where I'd love to hear from you.

I've set it up like in this link but I'm not getting any spark. I got just under 12v going to both wires on the coils and it doesn't seem to be switching to ground like it should. I've checked my ohms on the coils and they are in spec. The HEI units are suspects because as soon as I connect the coils the HEI terminals all have + power. Are my units faulty since they are cheapies from Amazon or am I doing something wrong? I was ok with them working and possibly burning in short order. As long as it gave me a spark so I knew I was on the right track. I installed the resistor circuit as well. I'm thinking on going to the junkyard and getting genuine GM units if that will help otherwise I was going to run the new dyna 2000 which I've read can be troublesome with the pickups in the hot oil.

I'm wanting to do some distance runs and if there are issues I could go to any parts store for repairs, that's what started this whole venture.

Let me know what you think or advise towards.
Thanks
Jeff
 

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The ignitors in the Honda system are garbage and extremely weak compared to the HEI setup. If AMC49 was still posting he would agree since he's been running this system since the 90s. You get a spark that hits harder than you could ever achieve from the stock system. You would be surprised at how weak a good running system actually is.

To you question about gains, it's about breakdowns and not waiting for parts online. I can go to any local parts store to get ignition parts while doing long distance runs.

The problem was the Amazon HEI units. It's running great and strong with .060" spark gap. Plugs are cleaner than they have ever been. 🔥⚡
 
When you say HEI units, are you refering to the GM style "Ignition Modules"? If so then you should tighten the plug gap a bit. The .060 that you are running is probably what is taking them out. I know the guy that developed the HEI system for GM and he would tell you the same thing. Use the genuine GM (Delco) Modules and tighten the gap and you won't have any issues. Echlin brand from Napa aren't too bad. Chinese stuff is a waiste of time.
 
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When you say HEI units, are you refering to the GM style "Ignition Modules"? If so then you should tighten the plug gap a bit. The .060 that you are running is probably what is taking them out. I know the guy that developed the HEI system for GM and he would tell you the same thing. Use the genuine GM (Delco) Modules and tighten the gap and you won't have any issues. Echlin brand from Napa aren't too bad. Chinese stuff is a waiste of time.
Very interesting so there is a solution for the old spark generators. Please I would like to know more about this, the model nr. of the GM HEI or NAPA module needed and the schematics to set this up. Weak sparks have been my problem since I bought my CB1000C. Your help and experience is highly appreciated.
Shon Ton
 
Look up. The person that started the thread left a schematic. It's one of many you could probably find on the internet.
 
The hard part is getting the coils to fit under the tank and finding a good spot to mount the modules. The is another coil pack system from a Dodge neon that is either smaller or has 4 plug terminals on one pack. The wiring is a bit different with more diodes and different resistors. It hasn't been verified but in theory it should work with the dwell required from the setup.

I'll close the gap on mine since I'm running stock plugs. The guy with .060" has a pretty modified engine and running iridium plugs. His explanation is that the older Cavaliers and Berettas that used these coil packs have a factory gap of .060" and will run upwards of .100 by the time they are serviced. They deliver a ton of spark energy for what they are and quit running because of deposits on the electrodes. I agree .060 is excessive but .040-.060 gives an enormous flame kernel that the stock ignition could never give.

I'll put some miles on it and see what happens. I got 2 extra modules I'm going to keep with me in case I do burn something out. I would love to use the dyna setup since it has advance curves and rev limiters built into it but I'm concerned about the pickup coils in the hot oil. Apparently there is issue that dyna haven't worked out. Half say they've ran the setup for 20 years the other half say the hot oil burns the pickups out and dyna won't honor them. Idk well see how ith goes. 😬😊
 
The guy with .060" has a pretty modified engine and running iridium plugs. His explanation is that the older Cavaliers and Berettas that used these coil packs have a factory gap of .060" and will run upwards of .100 by the time they are serviced.
The fact that your guy is running a modified engine and Iridium plugs should be no reason to run those gaps. You will not notice a difference in performance changing the gap from .044 to .060. What you will notice is longevity of the parts. The GM HEI Module was designed to make significantly more spark energy, to bridge increased plug gaps. But, there is a limit. Once you go to the larger gaps like your friend, you are putting much higher demands on the system and you start to get component failure. Once GM started opening the gaps to .060 and even .080 they started having component failures.
 
The only weak spot that I have found in the OEM DOHC ignition has been the unreliable Honda generation of coils used on them. The next generation of Honda coils has a much better reputation, the ones marked MP08. MP08 coils are available used on ebay for about $10 to $20 each and have a better reputation than all of the very expensive high performance aftermarket coils available.
 
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