Mallory tech answer to coil/ballast ?

Bubbas, It was wired up without the resistor? Are all of the Mallory coils made in China, or just the new stuff, mine is about 5 years old. How about the USA made coils you buy. Do you sell those to customers? Looks like after all of this discussion those of us with ballast resistors better not take them out. Thanks!
 
Tom's36coupe said:
Bubbas, It was wired up without the resistor? Are all of the Mallory coils made in China, or just the new stuff, mine is about 5 years old. How about the USA made coils you buy. Do you sell those to customers? Looks like after all of this discussion those of us with ballast resistors better not take them out. Thanks!
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This one wasnt a mallory but made in china from another supplier.
Yes we do sell our coils , they are $61 . Havent put them on the web site yet, but will get it done soon...
I didnt have a resistor in the circuit ( the customer said thats the way he was running it) i cant believe this coil got so hot in a few minutes!
I wish i had put a amp probe and scope on it , would have looked interesting for sure. I may try that tomorrow after it has cooled down over night..
 
Hello!

I contacted Mallory regarding my Mallory distributor 27 series with dual points. It needs 3 ohms (original resistance wire 1.5, MSD blaster 2 coil 0.7 and ballast resistor 0.8= total 3 ohm) so I seem to have the right parts installed.

However, the ballast resistor increases to 1.5 when hot, so I´m thinking I could skip it and buy a coil with 1.4 primary resistance and combine it with the original wire resistance wich gives me a total of 3 ohms. What do you all say? My car was shaking and died last week and I thought I solved by changing coil and condenser, but then it happened again the day after. I think this was casued by to much resistance caused by the warm summer (no problem touching the coil). I have no reason to suspect vapor lock, but I do think that the new condenser was bad.
 
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Tom's36coupe said:
Rich, I am sure our friends at Bubbas will chime in for some help. I would like to get rid of the ballast resistor for two reasons, clean up the engine compartment wiring and possibly better performance. I always understood that because of the way the combustion chamber is on a Flattie the spark has to travel a long way, just makes sense to me that the hotter it is the better? hey what do I know though, I am just a Jeweler! lol......
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Tom, It has probably already been cleared up a bit for you, by Bubba's last (and excellent ) post. Though to make point of it, the spark just has to fire the plug (jump the gap) the burning characteristics of the flame front, in a flathead combustion chamber, are another subject, after the fact.

Bubba, I assume that each of these Ballast resistors is there for the sole purpose of completing each particular system, so as to have a higher voltage cold start facility. (if not, I probably missed the whole point)
 
Ok, thanks.

What I want to know for sure is if I can I can choose between two different methods to get 3 ohms so that the points will not get damaged. Are you saying that I should stick to alternative 2?

Alt. 1: skip the ballast resistor and instead buy a coil with an internal resistance of 1.4 instead of 0.7. The effect is the same along with the resistance wire, ie. total of 3 ohms. Also, I know what I get because the ballast resistor increases from 0.7 to 1.5 when it gets hot, which I think could be a problem during extreme summer heat.

Alt. 2: keep the 0.7 ignition coil, 0.8 ballast resistor and 1.5 resistance wire that together will result in 3 ohms.
 
The resistor as far as I can tell has a multi function purpose ,The word ballast describes it and it is a stabilizing influence .
 
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Gasoline said:
Ok, thanks.

What I want to know for sure is if I can I can choose between two different methods to get 3 ohms so that the points will not get damaged. Are you saying that I should stick to alternative 2?

Alt. 1: skip the ballast resistor and instead buy a coil with an internal resistance of 1.4 instead of 0.7. The effect is the same along with the resistance wire, ie. total of 3 ohms. Also, I know what I get because the ballast resistor increases from 0.7 to 1.5 when it gets hot, which I think could be a problem during extreme summer heat.

Alt. 2: keep the 0.7 ignition coil, 0.8 ballast resistor and 1.5 resistance wire that together will result in 3 ohms.
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Kinda ?
The issue becomes a wattage issue. Using a 1.5 ohm coil and a 1.5 ohm resistor divides the wattage between the two components. This division also divides the heat built up in each.
 
When a coil is said to be 1.5 ohms and a resister is 1.5 ohms that is not true 3 ohms.
If you put a volt meter across resister it should read about 3 volts that's about 2 amps. A coil is not a resister. best have it running pos at coil to grd about 9 volts.
Best get a know good coil not a master blaster forien junk.
 
This is a great forum!

OK, I´m gonna stick to my Mallory distributor, original resistance wire, MSD blaster 2 coil and the ballast resistor. It might have been a bad condenser (out of the box) that killed my car that sunny day. I also noticed that I installed the condenser bracket upside down so it was pressing against the distributor lock and maybe it did not close properly - it´s a vacuum advance.
 
I must admit that when I installed the new msd coil and ballast resistor recently, I connected the wires wrong, ie. resistance wire to the negative side of the coil and the cable from the distributor to the positive side. The car was impossible to start, but the question is whether it could have damaged the ignition coil and ballast resistor? I discovered it after a few tries.
 
BillM ...

I'm not sure of the tempco for the ballast resistor, but any coil which is wound with copper wire (all of them I believe) has a positive tempco of .293 % per degree C. Check the spec on the coil, the 1.5 ohms is probably at room temp. Pick a number for the internal coil temp after a hot run .... probably around 80C, maybe more. If so 80C-25C= 55C degrees. The increase in coil temp will then be 55 x .293=16% increase.

If the coil is 1.5 ohms at room temp (25C) then it will increase by 16% at 80C or .24 ohms. The new coil resistance will then be 1.74 ohms.
 
The only way to tell coil resistance is adding a resister like 1.5 ohms for 12 volt car.
OHMS law 1.5 ohms at 2amp is 3 volts, leaving the coil resistance of ?
12 volt minus 3 volts is 9 volts
9 volt didved by 2 amps is 4.5 ohms. E= IxR
A coil used on big truck, vws, other use no ext resister.
I would think its more then 4 amps for 12 volts.
resisters stay mostly what they are rated +-
coil amps is important high amps burns points.
 
Below are some results I measured on my 8BA with a 6V coil, and a nominal 1 ohm ballast resistor. It has been converted to 12V.

I found the best way to estimate the primary current was by adding another small series resistor ( 0.18 ohms) between the coil and ballast resistor. Or measure the current directly.

Here are the measurements, and the resulting calculated currents and resistances:

Meas Battery V : 11.87V (engine not running, points closed)
Meas V current sense resistor: 0 .752V
Meas V coil (cold) : 4.95V
Meas V ballast resistor (cold): 5.90V

Adding all these gives 11.60V vs 11.87V measured across all of them.

Calculated coil / ballast resistor current = V sense/R sense=.752V/.18 ohms= 4.2A

Calc coil resistance = V coil/I coil = 4.95/4.2A= 1.2 ohms
Calc ballast resistance = V bal/I coil = 5.9/4.2A= 1.4 ohms

The ballast resistor is marked as 1 ohm, so it seems a little high.

As it warms up over time, the current drops to 3.5A and calculates out to 2.2 ohms.

Hope this helps
Al
 
Found a page on the web that gives a good explanation of ballast resistors. It states there that "Due to a high temperature coefficient of the iron-wire resistor, the hot resistance is about three times of the cold resistance."
See: http://what-when-how.com/automobile/conventional-ignition-systems-automobile/

Scroll down to: Output Control Ballast Resistor.

It also states: "The resistor can be installed either internally in the coil or externally in the circuit."
 
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Wow. Not good at maths. I have a Bosch SU12 coil which is supposed to run without a ballast resistor (ie, it has a built in one). After reading this thread I'm confused as to whether I should run an external ballast resistor or not. Dist is crab type, system is 12v.
 
If a company sells coils and says no resister needed and your car runs go let it go.
coils topic never ends , people put them is backward use 6 volt coil on 12 volts, measure ohms. If you run a 6 volt coil with 12 volts do you run your car on rode?
If you use a 12 volt coil and resister say 1.5 ohms your current is low about 2 amps.
All testing should be running under correct operation.
If have a car worth 5,10,20,ect k use the best coil you can buy.
Bosch SU12 just for kicks put a amp meter in series and see what it reads running.My guess its less then 3 amps.
 
Confused. Me too.
Here are four common system variations, that I understand.

1. A Ford 6 volt coil is actually a 4.5 volt coil that needs the in dash resistor.
2. An aftermarket 6 volt (true 6 volt) needs no resistor. (bypass the ford resistor)
3.A 12 volt coil can run on 12 volts no resister and no ballast.
4.A ballast coil for a 12 volt system is in reality a 9 volt coil that is used in conjunction with the appropriate external ballast.

The resistor in No1. is Fords way of aiding starting from cold because as the resistor heats up the voltage to the coil drops to the 4.5 volts from the 6 volts it gets when the resistor is cold.

The ballast system is another cold start aid for a key start system. When the key is in the cranking position, the ballast is bypassed, feeding the full 12 volts to the coil. when the key is released the feed to the coil is directed through the ballast resistance and so the coil is fed only 9 volts while running.

I understand that the electronic systems need a special coil?

Bubba, can you please answer these for me;
1. Are there coils with built in ballasts, or am I missing something?
2.What are the applications (when are the different ones used) for the three different primary?) resistances that you mentioned?
 
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