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Question about ignition coil
#1
Hi guys,
I currently have big Hei distributor /ignition ready to run unit. It's too big and I can't use my ram air because of it.
I ordered smaller hei distributor and would like to use ignition coil canister that I had laying around... It's a original Ford Fd471 unit that requires external resistor

Now, I have already cut half of my resistor wire going from the ignition switch /tach to the coil

Question is do I really need external resistor because i have switched from points to electronic ignition

Let me know what you think...

I just don't want to spend another 50 dollars unless it's really necessary
Thanks
Alex

Sent from my ONE A2005 using Tapatalk
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#2
why do you want to run an expensive distributor but a stock low voltage coil?
  Reply
#3
barnett468;284637 Wrote:why do you want to run an expensive distributor but a stock low voltage coil?

Hi
I was under impression that this unit produces about 40000 volts...
New Pertronix unit produces the same 40000 volts and it has internal resisitor

https://www.amazon.ca/PerTronix-40011-Fl...B00199F2WW

What coil would you recomend ?
I would prefer canister coil since I dont want to drill to many holes in the engine bay.

Thanks
Alex
  Reply
#4
yes the flame thrower coil is a high voltage coil . you said you wanted to run a stock ford coil.
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#5
barnett468;284653 Wrote:yes the flame thrower coil is a high voltage coil . you said you wanted to run a stock ford coil.

Yes I did. I was under impression that stock would also be around 40000 Volts....
I think i'll just go with Pertronix since it is new and from reputable company
Thanks for your help
Alex
  Reply
#6
As you are a new member, welcome by the way, you likely will not have read the many posts on the subject of distributors and timing. A search in the top right box will bring up loads of info to help.
To be honest, I do not know why people want to install a GM style distributor in a Ford anyway. You have a ram air car, so unless you are doing a complete engine mod with all the bling, why?
In my case, I wanted to keep the factory look. It took time and much help from the guys here to learn what was needed for my 71 Mach 1 351C 4 V non ram air car. Most re-manufactured Ford distributors as well as new, I found were way off as far as timing was concerned ( too much mechanical advance) . I'm not going into that too much now, but my suggestion would be to go with a factory style dizzy, set up the curve to no more that 34 degrees mechanical with only 3-4 degrees of vacuum added and vacuum connected the timed port on the carb, 14 degrees of initial timing and then use a Pertroix Ignitor II and a Flamethrower II coil. The coil and Ignitor MUST be matched. Do not use an Ignitor II with a Flamethrower III coil and that came directly from Pertronix. The Ignitor III's are currently junk on the Ford distributor. I am not going there at this point, but I have first hand experience with this, trust me, I know.
Hope this helps you sort out some of your concerns.
Geoff.
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#7
Alex,
It sounds like you have a factory tach?

If yes, then you will need some kind of resistance in the ignition line in order to keep the current level down. I believe, too much current will eventually burn out the tach as well as the points. Usually the resistance is about 3.5 ohms( pink wire ) in addition to using the 3.5 ohm Pertronix II coil which results in about 6v to the coil.

If you have cut some of the pink wire, you will have a little more than the 6v as well as a little more current flow but everything should still work OK.

If there is no tach or you bypassed the factory one, then you should be able to use +12v ( or something less depending on resistance ) to the Pertronix coil +.

+12v should be going to the Pertronix module in the dizzy, in any case.
  Reply
#8
The stock Ford coil is not a 40,000 volt coil, probably around 25,000 to 30,000 volts.

I borrowed this from another post at http://www.7173mustangs.com/thread-accel...stock-coil :
An interesting thing about coils is that they just produce enough voltage to bridge the spark plug gap. The total potential voltage is governed by the saturation current in the primary windings, the winding ratio between the primary and secondary windings, and the iron core. The primary side is charged when the points are closed (or connected to ground by an electronic ignition). As soon as the points are opened (or the ground removed) the magnetic field created by the primary windings collapses almost instantly through the iron core and secondary windings creating the high voltage necessary to bridge the spark plug gap. As soon as the spark is created the field is discharged and the voltage does not get any higher.

Our cars, with a 0.35" gap and 10:1 compression, require about 12,000 volts to fire the spark plugs. The wider gaps, that came about as car makers tried to improve the efficiency, required higher voltage coils.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#9
SteveO_71;284664 Wrote:Alex,
It sounds like you have a factory tach?

If yes, then you will need some kind of resistance in the ignition line in order to keep the current level down. I believe, too much current will eventually burn out the tach as well as the points. Usually the resistance is about 3.5 ohms( pink wire ) in addition to using the 3.5 ohm Pertronix II coil which results in about 6v to the coil.

If you have cut some of the pink wire, you will have a little more than the 6v as well as a little more current flow but everything should still work OK.

If there is no tach or you bypassed the factory one, then you should be able to use +12v ( or something less depending on resistance ) to the Pertronix coil +.

+12v should be going to the Pertronix module in the dizzy, in any case.

Good point on the resistance wire. From my communication with Pertronix, they told me that only the Ignitor I need not have the resistance wire bypassed. The Ignitor II can go either way, but recommended it be full 12 V. The Ignitor III MUST be a full 12 V . I would have to think that as the factory tach is a positive feed, it would need to see a resistance the same as the original installation. That's just my thought on it.
  Reply
#10
Stanglover;284663 Wrote:As you are a new member, welcome by the way, you likely will not have read the many posts on the subject of distributors and timing. A search in the top right box will bring up loads of info to help.
To be honest, I do not know why people want to install a GM style distributor in a Ford anyway. You have a ram air car, so unless you are doing a complete engine mod with all the bling, why?
In my case, I wanted to keep the factory look. It took time and much help from the guys here to learn what was needed for my 71 Mach 1 351C 4 V non ram air car. Most re-manufactured Ford distributors as well as new, I found were way off as far as timing was concerned ( too much mechanical advance) . I'm not going into that too much now, but my suggestion would be to go with a factory style dizzy, set up the curve to no more that 34 degrees mechanical with only 3-4 degrees of vacuum added and vacuum connected the timed port on the carb, 14 degrees of initial timing and then use a Pertroix Ignitor II and a Flamethrower II coil. The coil and Ignitor MUST be matched. Do not use an Ignitor II with a Flamethrower III coil and that came directly from Pertronix. The Ignitor III's are currently junk on the Ford distributor. I am not going there at this point, but I have first hand experience with this, trust me, I know.
Hope this helps you sort out some of your concerns.
Geoff.

Hi
Good to be here. This site has lot's of useful information about these big body mustangs.
I bought my car with big all in one HEI distributor... PO has modified resistor wire by cutting half of it and connecting it to the Batt terminal of the HEI distributor.

why do I want HEI?
Simplicity. I dont have to order original distributor , + pertronix module then put everything together. So I chose the small cap HEI distributor (That looks almost identical in size to original ford distributor). All I need to add is the coil to it.

It will clear filter and RAM air as well.
I do have Tach and it is currently working fine with HEI unit.

Thank you
Alex
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