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 GM HEI: Cheap and Extremely Effective Ignition Upgrade 
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Joined: Thu May 19, 2011 2:35 pm
Posts: 11
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Will be trying this upgrade tomorrow. Hopefully I have everything right and it works.


Wed May 25, 2011 8:26 pm
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Joined: Thu Jan 04, 2007 2:26 am
Posts: 611
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Yotetalker wrote:
Will be trying this upgrade tomorrow. Hopefully I have everything right and it works.


Are you using 4-pin or 7-pin HEI modules? Just curious, because I only have experience with the 7-pin modules (the salvage yards don't have any 4-pin modules left).

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GM HEI: Cheap and Extremely Effective Ignition Upgrade

Universal Rectifier/Ford Regulator Conversion


Thu May 26, 2011 3:02 am
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Joined: Thu May 19, 2011 2:35 pm
Posts: 11
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
I will b using the 4 pin due to I bought them new through the auto store. I bought used coils at salvage yard. If it works like I hope it does this should take care uf my hard starts.


Thu May 26, 2011 3:01 pm
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Joined: Thu Jan 04, 2007 2:26 am
Posts: 611
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Yotetalker wrote:
I will b using the 4 pin due to I bought them new through the auto store. I bought used coils at salvage yard. If it works like I hope it does this should take care uf my hard starts.


Be sure to add in the +1.4v start booster shown in the diagram to help cold starts. Makes a huge difference.

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GM HEI: Cheap and Extremely Effective Ignition Upgrade

Universal Rectifier/Ford Regulator Conversion


Thu May 26, 2011 6:31 pm
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Joined: Thu May 19, 2011 2:35 pm
Posts: 11
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Not for sure what ur talking about on the booster. Am I over looking something. How's the coil fit under the tank or do they. I haven't had a chance to work on yet due to a sick child. But will very soon


Thu May 26, 2011 8:06 pm
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Joined: Thu Jan 04, 2007 2:26 am
Posts: 611
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Yotetalker wrote:
Not for sure what ur talking about on the booster. Am I over looking something. How's the coil fit under the tank or do they. I haven't had a chance to work on yet due to a sick child. But will very soon


The start booster I'm referring to is the resistor-diode string (R1, D1, and D2 in the diagram). The resistor limits the current and the diodes give the modules a 1.4v "bias" which produces a stronger reluctor signal. This is important when the engine is cranking slowly and the battery voltage is low.

Image

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GM HEI: Cheap and Extremely Effective Ignition Upgrade

Universal Rectifier/Ford Regulator Conversion


Thu May 26, 2011 9:02 pm
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Joined: Thu May 19, 2011 2:35 pm
Posts: 11
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Yes I will be using the resistors and diodes


Fri May 27, 2011 3:20 pm
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Joined: Thu May 19, 2011 2:35 pm
Posts: 11
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
I would to get some pics of ur guys coils and the setups on them and a pic how u mounted them to the bike. The coils I have have the heat plate mounted to them


Tue May 31, 2011 11:31 am
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Joined: Thu May 19, 2011 2:35 pm
Posts: 11
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
ok i got it hooked up and it will run until you let off the button.My question would be what do the all white wires go to and the all green wires, do they just tie together white to white and green to green. they go to the generator as the wireing diagram shows. My coil wires are as follows 1/4 all yellow and 2/3 blue with yellow tube.

this is what I have so far:
BLK/white stripe to term B on both HEI
BLU to term G first HEI
Yel/BLU tube to term G second HEI
Yel to term C second HEI
BLU/YEL tube to term C first HEI
Jumper from bothe G term with diode and resistor all going to start relay RED/Yellow stripe.
Both HEI are grounded


Any help would be greatful


Thu Jun 02, 2011 8:40 pm
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Joined: Thu Jan 04, 2007 2:26 am
Posts: 611
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Yotetalker wrote:
ok i got it hooked up and it will run until you let off the button.My question would be what do the all white wires go to and the all green wires, do they just tie together white to white and green to green. they go to the generator as the wireing diagram shows. My coil wires are as follows 1/4 all yellow and 2/3 blue with yellow tube.

this is what I have so far:
BLK/white stripe to term B on both HEI
BLU to term G first HEI
Yel/BLU tube to term G second HEI
Yel to term C second HEI
BLU/YEL tube to term C first HEI
Jumper from bothe G term with diode and resistor all going to start relay RED/Yellow stripe.
Both HEI are grounded


Any help would be greatful


It ran momentarily so you're almost there!

Are you using the original diagram in the original post for 4-pin modules, or the diagram for the 7-pin modules?

You say the bike will die as soon as you let off the starter button? Sounds like you don't have a ground reference for your reluctors...

In the original diagram in the original post (4-pin modules), you're looking at the YEL/Wht Tube and BLU/Wht Tube wires, which should be grounded.

NOTE: In the 7-pin diagram, the 1.4v reference signal is constant (on with ignition power). In the 4-pin diagram the 0.7v bias is only active while the starter button is being pushed.

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GM HEI: Cheap and Extremely Effective Ignition Upgrade

Universal Rectifier/Ford Regulator Conversion


Fri Jun 03, 2011 12:01 am
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Joined: Sat Jun 11, 2011 3:45 pm
Posts: 8
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
New guy around here. Wanted to share that my good buddy wanted to get into motorcycling (after I started him with my 50cc backup/girlfriend scooter). So he found a 1982 Nighthawk 650 with about 36,000 miles on it. While I did not precisely recommend this ride to him (it's in shabby condition), I am elected to work on this poor little abused motorcycle.

Long story short it runs OK until the ignition coils get hot. At any consistently high RPM (over about 5,000 RPM) there was serious misfiring and power shortage. An ohm meter and some careful testing led me to ignition coils.

With no expense being spared, and having my own discount as an Autozone employee I purchased 2x DR100 ignition control modules ($24.99 each) and 2x C849 coils ($26.99 each). I picked up the appropriate resistors and diodes and got to work with my soldering iron.

This is an old and tired engine. It has some oil leaks, it burns a smidge of oil on cold start, and I think the carbs probably need to be at least checked for synchronization. Overall though it runs OK all things considered (until it warms up).

I will also say that for this project I have made my own ignition wires from NAPA Beldan 7mm ignition wire ($1 per foot) with boots ($1.70 each) and high tension terminals ($0.70 each). I think that I may ultimately choose to go the route of a quality Iridium spark plug for this project given the arc force of the HEI coil and the propensity for gap erosion that most copper plugs have with the GM DIS ignition systems.

Lastly of note, the Nighthawk does not have space under the seat for the ICMs so I have cut off the factory tool box mount and plan to mount them under the left side panel with some fabricated aluminum bar stock. Coil mounting would interfere with the gas tank so brackets for the ignition coil will likely have to be fabricated as well.


I will post back when I have things running. Big thanks to Pinhead for posting all this information. I doubt I would have dared tackle this job without this post as a guide.


Sat Jun 11, 2011 4:12 pm
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Joined: Thu Jun 02, 2011 2:45 pm
Posts: 3
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
Hey, I'm about ready to do this mod on my bike. I have about got this thing running and right after rebuilding the carbs, I found it was not charging. I ended up getting an older Ford external regulator and a rectifier bridge for a GM alternator for a total of $30. Now, Im trying to figure out where to mount the coils? It doesnt look like they will fit where the stock ones were under the tank. Anyone got any pics? PS - you can get NEW lifetime warranty 4 pin ignition modules at the parts stores for about $20-$25 each. Just ask for one from an early 80s chevy truck or something.


Sat Jun 11, 2011 8:43 pm
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Joined: Sat Jun 11, 2011 3:45 pm
Posts: 8
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
^^ As per my above post.

Coil number C849 "Ignition coil for a 01 Chevrolet cavalier with 2.2 4 cylinder please."

Ignition module DR100 "Ignition control module for a 1984 Chevrolet C10 with the 5.7 please."

Trust me, corporate auto parts, ask for "early 80s chevy ignition module" you're not gonna get service. I'm not proud of this as I work as a manager at Autozone, but our counter people are lucky to get paid what your average McDonald's pays a grill worker (worked for McDonald's as a manger for 2 years too). Corporations man.

Love this mod for the record. Can't wait to see if I can get her running tomorrow after I get off work. :)


Sun Jun 12, 2011 2:42 am
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Joined: Thu Jan 04, 2007 2:26 am
Posts: 611
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
It's good to hear the mod is getting more popular; it's amazing how much stronger the spark is and how much better the bike runs as a result.

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GM HEI: Cheap and Extremely Effective Ignition Upgrade

Universal Rectifier/Ford Regulator Conversion


Sun Jun 12, 2011 12:49 pm
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Joined: Thu Jun 02, 2011 2:45 pm
Posts: 3
Post Re: GM HEI: Cheap and Extremely Effective Ignition Upgrade
But where did you guys mount the coils? Can someone post some pics?


Sun Jun 12, 2011 10:13 pm
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