To make a long story long......

[Utard]

So it's Friday. It's a beautiful day to get the Mustang out of the garage and do some cruising around. I've had it out a couple of times since winter, so it isn't a maiden voyage.

The Mach is idling pretty rough. Damn these Cleveland's are cold blooded!

It takes some time to warm up.....

Plenty warm and still loping. That's just fine cause tomorrow is Saturday and I've got nothing to do. A tune up sounds like a fine idea and a good way to spend a Saturday afternoon. Now is a great time to get that vacuum gauge and do a real tune!

So let's have a look around and see what's in need of attention.

The plugs only have 300 miles on them, lets look under the cap.

Wow! Cap and rotor look terrible! Points look pretty bad too. Off to the parts store!

The fun is about to begin........

In go the points and it's time to gap.

Um, what the hell? The points plate is moving all over the place! How do you gap points that won't hold still? I wonder since I'm here and I just got this fancy vacuum pump tool what the condition of the vacuum advance is. Pump, pump, pump.... No vacuum. Nada. Nothing moves. Not a thing is advancing other than my confusion.

Maybe it's stuck, off it comes. Seems like it doesn't want to move but it will, and when it does it's pretty obvious that the diaphragm is completely shot.

Well, lots of phone calling and it turns out that nobody has a vacuum advance unit in stock unless I buy the distributor to go with it.

Well, I could spend a hundred bucks and get her running, or perhaps now might be the time to change out that distributor and quit messing with the points. Pretty easy decision. I've been eyeballing that Pertonix for a while now.

So, to finally come to the point......

The resistance wire!

Here is my understanding of what it means to bypass it.

I leave the underdash wiring alone, and hook up the wire that was going to the + side of the coil to the + side of the coil. I then run a new wire that is 12v switched to the red wire on the Pertonix module that comes out of the distributor.

Am I understanding correctly?

I have the factory tach and would prefer that it still work.

I'm planning to go with the ignitor II a new flame thrower coil.

If I am not correct in my understanding, which happens a lot, then would someone please be so kind as to walk me through what I'm supposed to do? Please be as specific as possible. I'm not completely stupid, but just dumb enough to make my life hard.

On a side note...

How the hell was my car running even marginally well with the vacuum advance not functioning at all? It never seemed to me that it had the power it should have, but it never backfired or stalled or anything. I wonder if that had anything to do with why it was so damn hard to get it to pass emissions.

Thanks for your help!

Scott

 

[will e]

Can't help you with the wiring. The vacuum advance only 'kicks' in when you step on it. There is also a centrifugal advanced based on RPM. So it not functioning won't have a lot of impact on normal driving. (This assumes you have it hooked up to ported vacuum)

 

[Wolverine]

The plugs only have 300 miles on them, lets look under the cap.

Wow! Cap and rotor look terrible! Points look pretty bad too.

How many miles on the cap and rotor?

..obvious that the diaphragm is completely shot.

All it takes is one crack

I've been eyeballing that Pertonix for a while now....I'm planning to go with the ignitor II a new flame thrower coil.

FWIW, the Pertronix Ignitor II IS NOT A HIGH ENERGY IGNITION SYSTEM. It is a system that only replaces the points and is only capable of a low energy spark...REGARDLESS OF THE COIL YOU GET. If you want your plugs to last longer, you need a High Energy Ignition system.

Most people here put their $$$ on the MSD HEI with EXTERNAL COIL and EXTERNAL Spark Box. I put my money on a Ford Duraspark Distributor with an external HEI Module and external coil. In the end, I think the MSD is about $400 give or take, the Duraspark $300.

The resistance wire!

Here is my understanding of what it means to bypass it.

I leave the underdash wiring alone, and hook up the wire that was going to the + side of the coil to the + side of the coil. I then run a new wire that is 12v switched to the red wire on the Pertonix module that comes out of the distributor.

Am I understanding correctly?

I have the factory tach and would prefer that it still work.

ASK ASK ASK whoever you get your distributor from to provide an ELECTRICAL DIAGRAM of your situation. This is a big bone of contention for me regarding aftermarket ignition manufacturers. They need to provide more specific information. I do not want to advise you in this regard because I do not have the tach.

However, attached is a PDF to get you started.

On a side note...

How the hell was my car running even marginally well with the vacuum advance not functioning at all?

You don't know that it wasn't working, because you didn't check it.

A quick way to determine if your vacuum advance is working is to remove the vacuum advance hose from the distributor, plug the hose, and check your timing, probably about 10 degrees BTD. Put the vacuum advance hose back on and your timing should increase by 20 degrees BTD or so.

The vacuum advance, centrifugal force springs in the distributor vary from application to application. Different cars, different engines had different vacuum advance timings as well as different spring to change the timing based on RPM. That is why you need to tune your distributor to your motor.

PertronixMustangXR7WithTach.pdf

 

[Utard]

Thanks for the replies.

I think the cap and rotor have about 500 - 600 miles on them.

You're right in that I don't know for certain that the advance wasn't working as I didn't check timing before I started my endeavor, but I'm fairly sure. The arm didn't want to move, and when after some gentle pressure it did finally move it was crunchy. The diaphragm was hard and brittle. I can't think it has been functioning for quite a long while now. I did check the timing last spring, but only with the advance removed. I never re-checked it after I hooked it back up, and I really can't remember if the rpm's changed when I did.

I understand (or at least I think I do) the difference in Pertonix and HEI. I've read your comparison post quite a lot of times. I guess I lean towards the Pertronix as it seems the easiest. If I was to do HEI, I would probably do like you and go the Duraspark route. I guess I mostly dislike the idea of the external modulator. The ford modulator is small and fairly unobtrusive. I haven't purchased anything yet, and I'm not completely sold on the Pertronix, its just what I've been leaning toward.

thanks again for the input!

 

[RacerX]

Wolverine, Thanks for the PDF. I've done similar to my car. I replaced the points with the pertronix III module.

I also added the Flamethrower II coil for better spark. This coil wants 12 volts. If I wire it like the PDF above, the coil will still see reduced voltage.

If I bypass the resistance wire by adding a wire from the tach straight to the coil, it'll probably burn out the tach.

Ideas??

Thanks, Curtis.

 

[Utard]

Thanks for the PDF Wolverine!

Looking at that, it appears I might have been right in my understanding of how to bypass the resistance wire.

If I were to go with the Duraspark HEI, would I still have a resistance wire issue?

 

[TommyK]

I wonder since I'm here and I just got this fancy vacuum pump tool what the condition of the vacuum advance is. Pump, pump, pump.... No vacuum. Nada. Nothing moves. Not a thing is advancing other than my confusion.

Maybe it's stuck, off it comes. Seems like it doesn't want to move but it will, and when it does it's pretty obvious that the diaphragm is completely shot.

That is the correct way to test the vacuum advance. If you put vacuum to it and it doesn't move it's NFG.

The plugs only have 300 miles on them, lets look under the cap.

Wow! Cap and rotor look terrible! Points look pretty bad too.

How many miles on the cap and rotor?

..obvious that the diaphragm is completely shot.

All it takes is one crack

I've been eyeballing that Pertonix for a while now....I'm planning to go with the ignitor II a new flame thrower coil.

FWIW, the Pertronix Ignitor II IS NOT A HIGH ENERGY IGNITION SYSTEM. It is a system that only replaces the points and is only capable of a low energy spark...REGARDLESS OF THE COIL YOU GET. If you want your plugs to last longer, you need a High Energy Ignition system.

Most people here put their $$$ on the MSD HEI with EXTERNAL COIL and EXTERNAL Spark Box. I put my money on a Ford Duraspark Distributor with an external HEI Module and external coil. In the end, I think the MSD is about $400 give or take, the Duraspark $300.

The resistance wire!

Here is my understanding of what it means to bypass it.

I leave the underdash wiring alone, and hook up the wire that was going to the + side of the coil to the + side of the coil. I then run a new wire that is 12v switched to the red wire on the Pertonix module that comes out of the distributor.

Am I understanding correctly?

I have the factory tach and would prefer that it still work.

ASK ASK ASK whoever you get your distributor from to provide an ELECTRICAL DIAGRAM of your situation. This is a big bone of contention for me regarding aftermarket ignition manufacturers. They need to provide more specific information. I do not want to advise you in this regard because I do not have the tach.

However, attached is a PDF to get you started.

On a side note...

How the hell was my car running even marginally well with the vacuum advance not functioning at all?

You don't know that it wasn't working, because you didn't check it.

A quick way to determine if your vacuum advance is working is to remove the vacuum advance hose from the distributor, plug the hose, and check your timing, probably about 10 degrees BTD. Put the vacuum advance hose back on and your timing should increase by 20 degrees BTD or so.

The vacuum advance, centrifugal force springs in the distributor vary from application to application. Different cars, different engines had different vacuum advance timings as well as different spring to change the timing based on RPM. That is why you need to tune your distributor to your motor.

Only if you are running full manifold vacuum. If you are taking vacuum from the ported source on the carb the initial advance should remain unchanged.

 

[Wolverine]

Without writing pages and pages:

1. To be clear, the Pertronix Ignitor in any form is an outstanding replacement for POINTS. Points were limited to 6V(except during STARTING) to keep points from arcing/wearing out prematurely. I mistakenly ran points at 12V and replaced them every 500 miles until I figured out what was wrong...pita.

2. Pertronix Ignitor is limited in the WATTS IT CAN DELIVER. Watts is determined by multiplying Volts x Current.

I believe the following specs to be true for Pertronix:

12 Volts Max

1.5 Amps Max

===============

18 Watts Max Energy to coil.

More watts than this and you fry the Pertronix....

3. Although there is no Specific Definition of HIGH ENERGY, I know a 4 pin HEI Module can deliver up to 5 AMPS:

12V x 5A= 60 Watts

Guess which wattage is capable of providing a higher energy spark?

I haven't even gotten to the coil yet.

Don't you wonder how they ever got that first internal combustion gas engine to run? I know it didn't run real well, but it did run...better than most Chevy'srun today (and that is my Chevy dig for the week).

Thanks for the PDF Wolverine!

Looking at that, it appears I might have been right in my understanding of how to bypass the resistance wire.

If I were to go with the Duraspark HEI, would I still have a resistance wire issue?

YES!!!

The resistance wire decreased voltage from 12V to 6V to keep the points from arcing.

HEI don't have points and therefore don't need the 6V limitation. And, because they can use 12V instead of 6V, right from the start you have 2x the power(actually 4x, but let us keep this simple).

One other little tidbit...

Wire gauging is based on AMPS.

Wire insulation is based on Voltage.

If you need 120 watts(amps x voltage) you can use

6V x 20A or

12V x 10A

With the 12V you can push the same watts with a smaller wire!!!

That is one reason the electric company uses 10kV, 20kV, 40kV and up in the overhead wires- So they can use less copper.

Originally, many cars were 6V. In 1955/1956 with power windows/heaters and such(before my time), one of the reasons they switched to 12V was so they didn't have to use fatter wire.

Wolverine, Thanks for the PDF. I've done similar to my car. I replaced the points with the pertronix III module.

I also added the Flamethrower II coil for better spark. This coil wants 12 volts. If I wire it like the PDF above, the coil will still see reduced voltage.

If I bypass the resistance wire by adding a wire from the tach straight to the coil, it'll probably burn out the tach.

Ideas??

Thanks, Curtis.

I have not done this...yet....but my understanding is you will need a ballast at the tach to provide 12VDC at the coil. The ballast will knock down the voltage to 6VDC. If I ever find a different way, or if you find a different way, post it in a new thread WITH a wiring diagram.