Author Topic: Converting from points to HEI  (Read 379 times)

Offline Loveofclassics78

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  • Name: D. Chatman
Converting from points to HEI
« on: January 31, 2018, 02:01:17 PM »
Good afternoon!
Currently working on 72 Eldo. Taking a poll, those of you who converted to an HEI setup, where did you run your new 12v wire from?  Did anyone replace the factory resistor wire with a regular wire?  I'm in the middle of the conversion and would like to get a couple of ideas of what I could use.  Thanks!

Don

Offline "Cadillac Kid" Greg Surfas 15364

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Re: Converting from points to HEI
« Reply #1 on: January 31, 2018, 04:13:26 PM »
Don,
Always the cleanest to go back and replace the original resistor wire as your lead to the HEI.  Be sure and disconnect the wire at the starter solenoid that currently provides 12V with the starter engaged.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Loveofclassics78

  • Posts: 47
  • Name: D. Chatman
Re: Converting from points to HEI
« Reply #2 on: January 31, 2018, 05:47:22 PM »
The original wire goes directly into the fuse box, correct?  So would you have to remove the wire and solder in another?

Online 35-709

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Re: Converting from points to HEI
« Reply #3 on: January 31, 2018, 06:37:33 PM »
What Greg said.
The original resistor wire originates at the large through-firewall connector plug on the engine side and goes to the coil.  On the other side of that plug, in the passenger compartment, is a pink #12 wire that goes to the ignition switch (and the fuse box), this is the switched ignition wire you want.

Guess you are familiar with, and prepared to deal with, the dual AC belt system interfering with the larger HEI distributor cap?

1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold
1950 Jaguar Mark V Saloon resto-mod

Offline chrisntam

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Re: Converting from points to HEI
« Reply #4 on: January 31, 2018, 08:39:55 PM »
I got my 12 volts at the ignition switch.  I left the resistor wire in place (but wrapped in the new loom) in case I (or others) ever want to put back the points distributor.
1970 Deville Convertible  MTS 507
Dallas, Texas

Offline TJ Hopland

  • Posts: 6941
Re: Converting from points to HEI
« Reply #5 on: January 31, 2018, 11:29:14 PM »
I think you are Ok in this case disconnecting the coil wire from the starter but some other cars you can't because the ignition wire from the key isn't live during cranking.  If you are not connecting it at the coil end ideally you would want to disconnect it at the starter too,  its not fused so can cause problems that are hard to pin down because you only see the sparks while you are craning.   Only took me twice killing batteries trying to start an engine that wasn't getting coil power during cranking to remember to always check that before a conversion or when you suddenly can't get started after replacing the starter. 

My 73 Eldo had a HEI in it when I bought it.  Both the original coil wires were crimped to what looked like what was likely the original BATT wire they clipped out of the donor car at the junkyard.   It ran fine for for I think 19 years till I put my second EFI system on it.   I had a very minor stumble after a few minutes of highway speed cruising.   It started when I switched from the HEI being a stand alone system to only using it for a pickup and letting the EFI system do all the work, basically just bypassed the internal module.   What I finally figured out was that the resistor wire was still in the circuit and for what ever reason the EFI systems ignition module was drawing more power than the HEI one did so after a few minutes the resistor wire (or maybe a bad connection) would heat up and the voltage would drop enough to cause the minor stumble.   

Over the years I had wondered about the resistor wire but could not find it on top of the engine and then 'they' say if its there you will read between 6 and 9v at the coil.   I'm not sure what kind of cars 'they' were working on but it doesn't seem to be early 70's GM's that used the wire.  I don't remember the exact numbers but at idle with the resistor in I was reading system voltage like 13.7 and 12.6 at the distributor coil.   Bypassed the resistor wire with I think #12 direct route from the bulkhead to the dizzy, no scenic route to the right side like factory and it brought me up to 12.9.    Maybe at high rpms its down to 9v but 'they' don't say to check it while doing 80 in the interstate.     

I'm assuming a 72 Eldo would be the same as my 73.   On my 73 the resistor wire starts at the bulkhead connector on the firewall.  The resistor wire is actually what is crimped into the pin in the connector on the engine side.  It kinda stands out, it looks different than all the other wires.  On the RWD cars it apparently pretty much makes a straight shot up to the engine and its clearly visible in the harness leading to the coil.   On the Eldo for some reason it runs in a harness across the firewall to the right side of the engine.  The splice back to regular wire is an inline crimp is basically above the transmission bell housing on the right side of the engine.   There appeared to be a fair amount of corrosion at both ends of that wire.  I think it has steel in it so in addition to normal corrosion issues you have additional issues because of the dissimilar metals at the splices and connectors.   

On other cars I had used a relay with the relay coil hooked to the original ignition coil wires.  The relay isn't a big enough load to care about the resistor so it engages just fine.  You can then find another good (fused) power source under the hood to feed the power to the coil.    Problem I have had in this era GM cars doing this is something possibly the 'gen' light back feeds just enough power to keep the relay engaged so you can't shut it off.  I simple diode in the correct place could solve that but last time I had that problem I didn't understand diodes or know where to get them so I have never actually done it.   

When I had the bulkhead connector apart I cleaned up and replaced a couple other pins.  Some of them appear to be main feeds that looked a little stressed.  The terminals in the bulkhead connector (and many other places on the car) are known as Packard 56.   If you search that you should turn up several options.    I may have done a post here giving the Napa part numbers for them.

I have put several HEI's in 68-74 Cads.   Never figured out any reason or rhyme to why some don't seem to have clearance issues with dual belts and or the 'smog' crossover pipe.  IF it hits the smog pipe it just takes a slight tweak to make room.   From standing over the engine looking at it you can't tell its been tweaked. 

Another option if you are not scared of the price or concept is something like an MSD6 ignition box.  Even the current models will trigger off points but its just using them as a signal so you don't get the arching that is the primary wear issue when used direct with a coil.    The 6 boxes give you all sorts of benefits and solve a lot of the possible conversion issues.  They hook to the old points coil wire for the ignition trigger, you can even leave the condenser installed.   They hook to the old + coil wire to use just as a turn on signal so they don't care about the resistor.  They then have power feed wires that don't need to be switched in any way and they recommend a fairly direct connection to the battery.   Then the have 2 wires that go to the coil.   If you find and install the right sort of connectors you can get it so you can easily bypass the box and go back to stock if it ever failed.   Biggest tip I have if you install one is to make darn sure the key is off if you are messing with anything ignition related,  they bite really hard.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Loveofclassics78

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  • Name: D. Chatman
Re: Converting from points to HEI
« Reply #6 on: February 01, 2018, 02:54:35 AM »
I have already installed the smog pump removal kit from MTS. I installed the kit with the new pulleys, so now clearance shouldn't be an issue.

From reading your posts, i believe the vote is to replace the actual wire. I just have to track it down. Any special tool used for removal?

Offline TJ Hopland

  • Posts: 6941
Re: Converting from points to HEI
« Reply #7 on: February 01, 2018, 08:59:28 AM »
I forgot the most important tip!   Assuming it still runs now with points take timing readings before you start.   Get a reading in several conditions idle with and without vacuum.  Get it at various rpms with and without vacuum.   Ideally have a hand vacuum pump to see what the vac does on its own.  Write it all down so if when you do the hei by the book and it doesn't run right you can compare to how the original setup was running. 

When I have installed HEI's I use plugs and gap for a 75 or 76.

Every option for bypassing the wire has its pros and cons.   I don't think any are super easy, they all have some hassle factor. 

I don't remember where the washer bottle was on a 72 but on a 73 its on the firewall next to the brake booster.  I removed that to get better access to the bulkhead connector.   I was not successful in removing the male terminal without damaging it.  After searching online I found out that most people have the same issue as me and just cut it.   If you have the blade horizontal you turn your cutter vertical and snip as deep as you can get it in the center.  That releases the lock so the rest will just pull out.   You get a new terminal for your new wire and it then just snaps into the connector block.  Napa part number for the female is NW725147.   Male is NW725145.

IF you go that route and run a new wire all the way to the dizzy be sure to either disconnect the extra wire from the starter or securely insulate both the coil and bulkhead ends.    I'm pretty sure a 72 has a 6 pin connector in the starter harness so that is an easier place to disconnect it than at the starter.  The engine end of the harness I think has the female pins in it which you can easily release with a small screwdriver.   That then isolates all 3 ends of that wire so it won't hurt anything.

If you just bypass the resistor itself and splice to the regular wire above the transmission you should not have to worry about the starter wire.   If anything it will help by sending a little more voltage to the coil during cranking since its a shorter wire than the one that runs through the key and fuse box.           
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Loveofclassics78

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  • Name: D. Chatman
Re: Converting from points to HEI
« Reply #8 on: February 01, 2018, 01:11:45 PM »
TJ,
So the wire above the transmission is a switching power source? Switching meaning power is delivered when the car is running.  What color is the wire?  That sounds like a good idea.

Offline bcroe

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Converting from points to HEI
« Reply #9 on: February 01, 2018, 02:06:59 PM »
I don't see much difference between removing the original points
ballast resistor, and just finding a way to attach a short around it. 
More important is that the job gets done, when converting to HEI.

Note points ign energy is limited by the current points can endure
before premature failure.  The ballast sets an upper limit on the
current, unfortunately also starting to limit max rpm energy.  The
current builds up after the points close, then (after charging the
coil) stabilizes at the limit set by the ballast resistor.  For this interval
all input is wasted heating the ballast resistor.  The points open, ign,
and the process repeats after the points close. 

HEI is able to calculate the point of time to turn on the coil current
(with a big transistor), JUST IN TIME to bring the coil to full charge
before interrupting the primary current for ignition.  The peak current
and charging energy are much higher than the points system.  But the
average energy is LESS that points, because all the energy wasted in
the ballast resistor is eliminated.  HOWEVER the HEI does need that
high spike of energy to work, so leftover resistance in a conversion
will severely handycap its ability to produce strong sparks. 

The coil primary voltage of any ballast system is going to continuously
change over every ign cycle, so a scope, not a meter, is needed to
determine meaningful numbers.  Bruce Roe

Offline Loveofclassics78

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  • Name: D. Chatman
Re: Converting from points to HEI
« Reply #10 on: February 01, 2018, 02:20:17 PM »
Let me make sure that I'm clear.  The entire wire from the coil to the bulkhead is considered the ballast resistor, is that right?  Or is it just a certain spot of the wire that you can cut out of it? Bruce, I didn't understand what you meant by short around it.

Offline bcroe

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Converting from points to HEI
« Reply #11 on: February 01, 2018, 07:01:23 PM »
Quote from: Loveofclassics78
Let me make sure that I'm clear.  The entire wire from the coil to the bulkhead is considered the ballast resistor, is that right?  Or is it just a certain spot of the wire that you can cut out of it? Bruce, I didn't understand what you
meant by short around it. 

The ballast resistor, is the part of the circuit path that offers a lot
more resistance to current flow, than a simple wire.  There would
be significant voltage loss through it with current flowing.  In my 62
the entire wire from the ign switch to the coil was special resistance
material, with different metal and higher temp insulation.  It could
be a block of ceramic with screw terminals connecting to regular
wires.  I don't know how yours is laid out. 

To defeat the resistance, connect a wire anywhere around the 2
ends, to provide what may be called a short circuit, or short.  Sort
of like cutting through the infield, instead of going around the outside
of the track.  Some uninformed call any electrical problem a short,
but that is not correct.  When the ballast resistor path is shorted,
there is no compelling reason to remove it.  But having located
it, removal and replacement with wire is a solution.  Bruce Roe

Online 35-709

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Re: Converting from points to HEI
« Reply #12 on: February 01, 2018, 08:44:55 PM »
You have a resistance wire, I believe the last year Cadillac used an actual ballast resistor was 1958.  The whole wire from the firewall connector (engine side) to the coil is a resistance wire.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold
1950 Jaguar Mark V Saloon resto-mod

Offline TJ Hopland

  • Posts: 6941
Re: Converting from points to HEI
« Reply #13 on: February 02, 2018, 10:10:29 AM »
73 Eldorado the entire run is not a resistor wire.  I assume 71, 72, and 74 is the same.  It may be the case on the RWD cars but like I said above in the Eldo for some reason they didn't take a direct route from the firewall to the engine plus the engine is a lot further from the firewall to start with due to the transmission.  The resistor wire runs from the bulkhead connector to that spice above the transmission on the right side.   There it splices back to normal wire and makes its way to the coil.    They could not just make the wire longer because that would change the resistance.   In theory they could have got a different spec resistor wire but I would guess it was just cheaper and easier to splice it. 

In my case since I have added other wires and hoses so I just made my new wire go from the bulkhead connector fairly directly up the left side of the engine to the distributor.   I left the original wires in place.   I originally planned on removing it and replacing it in the harness but changed my mind for some reason.   I don't remember if I had a good reason or if I was just lazy.   It may have been I wanted to get the bypass in and see if it solved my problem before I spent the time to run it so it looked better. 

What Bruce is saying about  'shorting past it' if you had the ceramic block type would be as easy as disconnecting the wires and jamming them together.   There was a car, maybe the early Mustangs? that had really easy to access terminals under the dash that made it really easy to run a bypass wire without having to tear into the original harness. 

In the context of a 73 (and likely 71,72,74) Eldo's would be you pull the bulkhead connector and release the proper terminal without damaging it.  The without damaging it is the first trick, maybe with the official tool it can be done but I don't think its possible with the usual assortment of small screwdrivers and pokey things.  Next find and expose the splice above the transmission.   Solder a standard wire around the neck of the terminal and re install it and the bulkhead connector.  Solder the other end to the splice then re insulate it and stuff it back into the loom.    This method should work fine for stock HEI applications and could either be hastily removed by just snipping the new wire or more extensively removed by de soldering the new wire.   

The wire/circuit in question is pink wire everywhere except the section that is resistor.  Its pink from the key.  It has a splice somewhere under the dash that splits it between the fuse box and bulkhead connector.  Looks like it feeds 3 fuses in the box.   DIR SIG, GAUGES TRANS, BU DEFG.  Looks like there is an un fused tap at the fuse box for the Guideomatic amplifier if you have one.   Since that was an optional item that could mean its a possibly unused socket in the fuse box that would be an easy place to tap in and run a new wire all the way to the dizzy if you liked that idea better than messing around with the underhood harness. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline TJ Hopland

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Re: Converting from points to HEI
« Reply #14 on: February 02, 2018, 10:45:38 AM »
Had some time to find the photos.   First time trying to upload direct so we will see how they come out.   Not sure if I will be able to shift the text where I want it or come back and edit it.  The part numbers were at my local Napa.  The splice was in that plastic loom stuff and wrapped with what looked like it was maybe some sort of rubber tape 40 years ago.  When I got to it it was more like dried out paper so pretty much all that was insulating the thing was the outer plastic loom stuff that in my case seemed to have suffered some heat damage and was also brittle.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline LV 57 SEDAN DE VILLE

  • Posts: 4
  • Name: Rick Morgan
Re: Converting from points to HEI
« Reply #15 on: February 02, 2018, 04:42:24 PM »
I just installed a point elimination kit made by Accel on a 57 Series 62 with a 365. Very easy install, uses the factory resistor (either ballast or resistor wire). Converts to a light beam breaker type system similar to a Mallory UniLite. The car starts so much easier and runs smoother than ever.

Offline TJ Hopland

  • Posts: 6941
Re: Converting from points to HEI
« Reply #16 on: February 02, 2018, 04:54:42 PM »
So the wire above the transmission is a switching power source? Switching meaning power is delivered when the car is running.  What color is the wire?  That sounds like a good idea.

In case the rest of the responses were too long or confusing the short answer is yes that wire is the original switched feed that is live during both run and start and originally fed the ignition coil.   The 'catch' is the resistor part that you want to get rid of and or bypass is between that splice and the bulkhead connector on the firewall.  From that splice to the coil is back to regular pink wire.   The resistor wire is odd looking.  Its stiff and the insulation is a thin white cloth like material.  Its got some color stripes on it but I don't remember them being very clear in my case.  Manual shows purple and pink.  I mostly found it because it looked and felt different than any other wire under the hood and I kinda knew where it should have been in the connector.   I think the connector is oriented differently in the manual than it is in the car so that can throw you at first when you are looking at it.   You have to look at the empty sockets or fat wires to figure out what is what. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Loveofclassics78

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  • Name: D. Chatman
Re: Converting from points to HEI
« Reply #17 on: February 03, 2018, 05:28:24 AM »
Good deal.  Thanks for the info everyone.  And to you TJ for the pics.   I found the wire and I will replace it since my distributor is going out for rebuild at Advanced Distributors.  Now that I have installed the MTS air pump removal kit, I hope I don't have any clearance issues.
« Last Edit: February 03, 2018, 06:19:36 AM by Loveofclassics78 »

 

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