Electronic ignition distributor conversion

[Los_Control]

4 hours ago, kencombs said:

Here is a good article on the whys and hows.

https://www.slantsix.org/forum/viewtopic.php?t=15779

Very good info there ... and very specific to get the ICM/coil from a 1996-2000 chebby. .... AC DELCO has some really good parts and is cheaper then just the Chrysler pigtail ... whats not to love?

 

I'm trying to figure out if my 1991 chebby stuff will work the same?

Makes sense that I have a chebby and have known good working spares on the shelf ... I replaced last summer while doing a tuneup .... just would be nice to have trucks that share the same parts.

 

Mounting is different, just not sure about internal voltages and have a question out on the chebby forum to see if there is a difference .... I will get the 1996 parts if that's what I need .... be sweet if I could use the 1991 though.

 

 

[kencombs]

4 hours ago, Young Ed said:

I also saw where someone melted the goo out of the back of the Mopar unit and used it to hide the GM one. 

I saw one of those too, but it seemed to me to be lacking a good heat sink.   And, the GM HEI module really needs one.

[Dartgame]

I think you can use that module, but its more common and well known to use the earlier style 4 pin module.

 

The 4 pins were used in GM distributors for their first generation HEI. These are the distributors that had the module mounted inside the distributor cap with the coil on top. I used a heat sink from a 1990's into to the 2000's chevy v8, lots of them in the boneyards on trucks, suburbans etc. You will need to file off one of the fins on the heat sink to fit the 4 pin module. Might as well take the coil pigtails and associated steel brackets the heat sink is mounted to, with the coil and so on if you want to use that style. You can modify them to suit your mounting position etc. I used a Ford Ecore coil and bracket from a 1990's mustang or Tbird.

[Los_Control]

32 minutes ago, Dartgame said:

I think you can use that module, but its more common and well known to use the earlier style 4 pin module

I was just sitting here doing some reading and research .... I think I can, they say you can use the earlier 4 pin style.

Mine is a 4 pin that sits inside the distributor and has no heat sync ... also is not HEI.

I believe HEI  you would gap your plugs at .045 and my truck uses a .035 gap.

Then I wonder if that is really a problem if I'm just looking for reliability and not performance?

 

So after thoroughly confusing myself, I decided to just follow the directions and go with the parts they recommend  

The AC DELCO  ICM is only $50, I will need to get the coil bracket  and heat sync from a wrecking yard.

I will need to upgrade my plug wires ... thats fine, needs new ones anyways.

All the needed parts will still be less then going with the Mopar ECU and their $130 pig tail. And have AC DELCO reliability.

[Los_Control]

So I watched a few vids today .... there is a lot of info out there on this mod .... Dead Dodge garage made it pretty simple to understand.

 

Thought I would add this here as a heads up.

I did get my distributor back together today and the last piece to install was the drift pin for the collar.

I found I had to remove the bottom brass shim for it to line up and install the pin.

I put all the shims back in as they came out of the 1949 distributor.

Even removing the 1 shim was not enough, with the pin installed the body now rubs on the collar and does not spin freely or no end play. .... Just a heads up to check for proper clearance before you button it up.

 

So after I clean up the bench tomorrow, I get to take it back apart.

I'm thinking the brass shims between the pieces are good to have .... I'm guessing my best way to correct this would be to remove a couple thousands from the body of the distributor, so the brass shims will go back in place.

 

Note to self, check that the distributor fits into the engine block before final assembly.

 

 

 

 

[Booger]

oops I just logged into the NASA website. No? I get that things get beyond repair or solution. and well fix it 

, dammit if it makes it better...bitchin. My last point tune up was a book of matches folded in half. might have been .019 or sumpin

but that was 20 years ago

[Sniper]

1 hour ago, Los_Control said:

Even removing the 1 shim was not enough, with the pin installed the body now rubs on the collar and does not spin freely or no end play

 

I ended up using some 1/2" ID thin steel shims to resolve that issue,  I just used however many it took to get almost all the vertical free play out,  Your local hardware store may carry them. 

[Los_Control]

10 hours ago, Sniper said:

 

I ended up using some 1/2" ID thin steel shims to resolve that issue,  I just used however many it took to get almost all the vertical free play out,  Your local hardware store may carry them. 

Probably overthinking it .... I'm guessing it would be a good idea to keep a brass shim as a sacrificial piece between the steel collar/shaft and the aluminum housing.

 

Probably be just fine without a "protective shim" ... but the factory did it this way?

 

I have 3 shims installed, I know now I need to remove 2. Removing 1 is not quite enough.

I put orange tape on the shaft just to keep the 2 shims from falling off and getting lost.

If I remove one of them, along with the bottom shim, would be correct end play ... but no sacrificial brass shim between collar and body?

 

OTOH, if I just milled a few thousands off the bottom of the housing ... I can keep all 3 shims in place.

2 shims inside the body keeps everything up off the floor and probably a good thing ... cap and rotor fits fine.

I imagine the body is cast and no 2 are identical ... why they have shims ... mine needs trimmed.

 

A wise man would probably remove 2 shims and call it a day 

 

 

 

[Sniper]

2 hours ago, Los_Control said:

A wise man would probably remove 2 shims and call it a day

 

Well, a good enough for government work type of guy maybe, lol.

 

A wise man does what eases his mind.

[Adam H P15 D30]

4 pin HEI module.  Heat sink off of a late 90s LT1

[Los_Control]

31 minutes ago, Adam H P15 D30 said:

4 pin HEI module.  Heat sink off of a late 90s LT1

Looks good. Rockauto sells the aluminum heat sync for $25 .... better if you can find one cheap at a wrecking yard.

I had a chunk of 3/16" aluminum in the scrap pile and made one. .... trying to hide it behind the coil but it stands out some

 

 

Curious what coil you are using?

Here I just have a stock 12v coil .... it works but I assume it will not work for long with a HEI module?

My research tells me a HEI needs a coil between 1.0-1.5 ohms .... A petronix flame thrower is $35 and 1.5 ohms.

 

I did start it once the other day and let it run for a minute .... no oil pressure gauge connected so it was pumping oil on the floor 

The engine started extremely fast and easy with the new setup and it sat and idled with no choke or throttle.

One time ....  Because of oil leak I just shut it off.

 

So the new petronix coil is suppose to be delivered today, will connect it and the oil pressure gauge and let it run for awhile and let it warm up and set timing and play with it.

 

So far the conversion to electronic ignition was a journey but much easier then I would have thought.

Curious to see after I have some time with it.

[Adam H P15 D30]

@Los_Control  I use the Petronix coils I saved from the failed Petronix set ups I remove.  Good coils, bad modules...

As long as the coil can handle 12v, the HEI module won't care.  In fact, running the 1.0 - 1.5 ohm coils just keeps the module cooler.