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Old 11-29-2010, 02:55 PM   #1
Tom's36coupe
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Default Mallory tech answer to coil/ballast ?

Reply from Rep:

You need around 1.5 ohms on the primary of the coil. This is between the key-on 12 volt source and the negative side of the coil. So either internal in the coil, loom resistor, and/or ballast resistor adding up to 1.5 ohms is required.
Reply from Customer:

Ok, thanks for the help. The new Mallory electronic coil states not to use a resistor so it has 1.5 ohms?
Reply from Rep:

coil #29219 has the resistance value built in, so no external resistor would be required.

Just got this response today from Mallory about the electronic coil and the correct 1.5 ohms. So it looks like for the last 6 years I have not had to use the ballast resistor. The next question is, how will my system run with a full 12volts, better, hotter spark? cleaner plugs, faster starting?
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Old 11-29-2010, 06:00 PM   #2
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Default Re: Mallory tech answer to coil/ballast ?

Tom ,

Good post.
Lets do the math:
Using a 1.5 ohm coil AND a 1.5 ohm ballast would give a total of 3.0 ohms resistance.
3.0 ohms divided into 12 volts= 4 amps of primary current ( close to maximum using contact points)
OR volts x amps = watts of 4x12= 48 watts of energy to make spark.

Now : 1.5 ohms with no ballast divided into 12 volts= 8 amps or watts = volts x amps of 96 watts of energy.

Now the problem becomes another issue with the 8 amps being very close to what the electronics can take requiring a current limiting circuit ( for protection) in the control. This could be lower than the 8 amps we figured above.
Example , GM HEI limits the current to 5.5 amps etc......

NOW the discussion can begin regarding to how much spark do you actually need ???
And the fact that a coil will only put out what is required, and the fact that flatheads are fairly low compression requiring very little spark to ignite the air fuel ratio.
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Old 11-29-2010, 07:36 PM   #3
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Default Re: Mallory tech answer to coil/ballast ?

Now its starting to make sense to me, thanks Bubbas! I guess my thinking has been: 3/4 race camshaft with 380 lift and 250 duration, merc crank, high flo valves, twin carbs and full 12v system with 40k coil. I need full voltage to make the party happen, or do I. If my motor was really lacking in the juice department it most likely would not be running so good. After Jim at Bubbas did the re-curve on my distributor, that was WAY off it really was running strong, the best it ever has, with the ballast resistor limiting the volts. Guess I am your good old consumer, always believing that I need the next best thing!
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Old 11-30-2010, 07:27 AM   #4
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Default Re: Mallory tech answer to coil/ballast ?

Tom/Bubbas,
Don't want to hijack your thread but this is the info I was looking for so if you don't mind I'd like to pursue it a little further. I have a Mallory unilite on my motor also, the only difference being I recently replaced my dual Strombergs with a Holley 390 carb. I have the 29216 coil with ballast on it now and have been running it this way for a long time, no problems, but was thinking I would change to the 29219 coil and eliminate the ballast. Mallory says the 29216 has .700 ohms primary, secondary 8.9K ohms and puts out 51K volts: the 29219 coil has 1.4 ohms primary, 10K secondary and puts out 58K volts. I'm using the Mallory supplied ballast but don't know the specs, have to ASSUME it's ~.7 ohms or they wouldn't have sold it to me (hah!). That means to me either coil will end up with the same resistance, just higher voltage output with the 29219. Doesn't that mean a hotter spark? It seems simpler to just have to 12 volt power straight to the coil without the resistor and let the coil do the work vs. the resistor. My 29216 coil/ballast are 10 years old and I'm thinking I need to replace them anyway when I re-wire the car soon so this is the time to get to the bottom of this. Thanks,

Rich
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Old 11-30-2010, 07:50 AM   #5
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Default Re: Mallory tech answer to coil/ballast ?

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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Old 11-30-2010, 08:38 AM   #6
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Default Re: Mallory tech answer to coil/ballast ?

From my experience with Mallory its best to run their whole package, The coil and surge protector. I had a stock ignition and just switched the distributor, then had several issues with the coil and the module inside the distributor. I spoke with the mallory rep and got set up with the correct coil , surge protector and cut out the factory resistor wire. After that it ran great. I wish I knew all that up front. Would have saved me breaking down a couple of times.
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Old 11-30-2010, 08:50 AM   #7
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Default Re: Mallory tech answer to coil/ballast ?

Tom; Thanks for letting me in. I have a new wiring harness to install and figured I would simplify as well as put a new coil on. I was originally going to hook the electric choke up to the + terminal on the coil but after reading the Holley instructions and talking to others, have decided not to. I agree that hotter seems better or at least can't do any harm. Guess I'll wait and see if Bubbas or anyone else can shed some light on this ballast/no ballast, 51Kv/58Kv before spending any more money. BTW, I have been running the surge protector.

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Old 11-30-2010, 02:15 PM   #8
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Default Re: Mallory tech answer to coil/ballast ?

Had a chance to use a current probe today with a couple different ignition coils etc .
After having some problems with various coils we now have our coils made by Andover coil in Layafette Indiana ( usa). We use three different coils being a .6 low ohm, a 1.5 ohm and a 4.0 ohm. All are oil filled canister coils.
The scope waveform shown below is from a contact distributor with ignition points and a 1.5 ohm coil with a 1.5-1.9 resistor in the primary much like we would like to see on a point equiped vehicle. Note that the current is turned on a the left of the waveform and turned off ( ignition fired) at the right. Current is built to a designed limit of a little over 3 amps. (good level for contacts)

The second waveform is the same distributor with no resistor in the circuit, note the rise time increases on the left ( some arcing is shown as well) and the current level is almost doubled ( 6.5 amps).
The spark plug with both ignition coils was firing at 8,000 volts.
The excess heat in the no resistor would have burned the contacts as well and over heated the igntion coil with the lowered resistance.

The same would happen to a electronic ignition controller , however the electronic controller would use a current limiting circuit to control this level and keep the module cool as well as the coil.

As someone said above you really need to use the entire system when buying a aftermarket electronic system.
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File Type: jpg points without resistor[1].jpg (45.7 KB, 37 views)
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Old 11-30-2010, 03:25 PM   #9
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Default Re: Mallory tech answer to coil/ballast ?

Bubbas,
Just for the record: I am running the entire Mallory system on my car; unilite distributor, 29216 coil, Mallory ballast resistor, and power cell (surge protector) as I said in the last post. Not having any problems, just was wondering if there were any pitfalls in changing over from the present system to the Mallory 29219 coil that doesn't require the ballast resistor, all the other stuff would stay the same. The other part of the question is; what is the significance of the difference in coil output voltage? The 29216 is 51K and the 29219 is 58K. To an ignition novice it appears there might be a performance gain there but your charts imply there may not be any advantage. This discussion is good stuff, I really like to get into the details before spending money after wasting hundreds in the past just trying different stuff that didn't always work. Thanks.
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Old 11-30-2010, 04:16 PM   #10
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Default Re: Mallory tech answer to coil/ballast ?

I think you are better off with the resister. Keeps the current to 3 amps with a 1.5 ohms resister.This is safer.That would drop 4.5 volts across resister,leaving the rest at coil.If you don,t like the resister put it under dash.AS for the extra volts out of coil,i don,t think you will ever notice it.I'm still running points and mine starts and runs good.
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Old 11-30-2010, 05:34 PM   #11
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Default Re: Mallory tech answer to coil/ballast ?

George,
You're probably right that I wouldn't notice the extra volts. The car starts at the hit of the button and runs fine so I'm not in a hurry to change anything. I have the resistor under the dash already, Tom said he wanted to get rid of his from under the hood just to clean things up.
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Old 11-30-2010, 05:52 PM   #12
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Default Re: Mallory tech answer to coil/ballast ?

Quote:
Originally Posted by Rich/Alabama View Post
Bubbas,
Just for the record: I am running the entire Mallory system on my car; unilite distributor, 29216 coil, Mallory ballast resistor, and power cell (surge protector) as I said in the last post. Not having any problems, just was wondering if there were any pitfalls in changing over from the present system to the Mallory 29219 coil that doesn't require the ballast resistor, all the other stuff would stay the same. The other part of the question is; what is the significance of the difference in coil output voltage? The 29216 is 51K and the 29219 is 58K. To an ignition novice it appears there might be a performance gain there but your charts imply there may not be any advantage. This discussion is good stuff, I really like to get into the details before spending money after wasting hundreds in the past just trying different stuff that didn't always work. Thanks.
I agree with George on leaving it the way it was and has been for years.
The gain in coil output would never be needed on a flathead or any other properly tuned up engine for that matter. Marketing at its best......
High current levels = high heat and high heat damages parts.
Q=Ever wonder why Nascar allows two ignition systems per car? A=They have trouble getting one to run 500 miles at high current levels....

There is three types of voltage in any ignition system.

1=Voltage required. This is what the engine needs to ignitite the air fuel mixture . Rich air fuel takes less and lean air fuel takes more . Higher compression takes more amd less compression takes less.
Typical engine needs 5-8,000 volts under normal loaded conditions and snap throttle may need 10-12,000 etc....
Plug will always only take what is needed (minimum).

2=Voltage Available= This is what the ignition coil could do if demanded ( such as a open wire etc) Maximam output of the coils windings and turns ratio-- Could be anywhere from 20,000 to 60,000 (high energy)

3=Voltage reserve= This is whats left over by subtracting required from available. Using 5,000 and have a 60,000 volt coil this reserve would be 55,000 volts.
I call this the public number on late models. The public can drive their car forever without doing anything to it as far as service , by the time we need 60,000 plus voltage the entire ignition is burned up, melted and destroyed !!!!!!
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Old 11-30-2010, 06:37 PM   #13
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Default Re: Mallory tech answer to coil/ballast ?

Thanks to all for the answers and opinions.Guess I can blame Mallory, lol.. They are the ones that started me thinking, does not need balast reisistor. Just trying to make the old girl run the best she can, since Bubbas has done my re-curve for me this summer I know its working at its best performance. I am going to hide the resistor somewhere and not worry about it.
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Old 11-30-2010, 09:29 PM   #14
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Default Question for Bubba on ballasts and coils

It's my understanding that ballast resistors have a temperature coefficient. When the resistor heats up the resistance increases, thus reducing the primary current and producing a regulating effect on the coil current. So if I am correct in this, does it also mean that the coils made for use without a ballast are made with primary wire with a similar temperature coefficient?
I have seen coils said to be designed for electronic ignitions, do you know if they are made without temperature sensitive wire? Seems like they would be just plain wire as the electronics is regulating the current.
Sorry to get into the nitty gritty but I get curious about this stuff.
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Old 12-01-2010, 06:33 AM   #15
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Default Re: Mallory tech answer to coil/ballast ?

I was looking at Mallary coil and says 1.4 ohms primary to maintain if less add resister.Now if that were so 1ohm you would need 12 amps to run. adding a 1.5 ohm resister would be total of 2.4 ohms that would be 4.8 amps.So it best to keep resister.
But when a coil is made and says no resister needed. When adding lose voltage across resister."More resistince less current "
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Old 12-01-2010, 08:00 AM   #16
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Default Re: Mallory tech answer to coil/ballast ?

Great thread, good information. The Flathead will never see more than 8-10K volts at the plug due to its CR. As far as coils are concerned a stock OEM coil/with resistor will furnish more voltage than your engin will ever need. I was wondering if the Mallory uni-lite distributor had a vacuum advance??
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Old 12-01-2010, 08:30 AM   #17
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Default Re: Mallory tech answer to coil/ballast ?

Ron,No vaccum advance on the unilite.
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Old 12-01-2010, 11:17 AM   #18
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Default Re: Mallory tech answer to coil/ballast ?

I have a 1.5 ohm coil as well and had nothing but problems, always stumbling, I added another 1.5 ohm ballast and it has run perfect ever since.

Mallory Dual Point with a 40,000 volt coil and a 12volt generator, don't know if that makes a difference
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Old 12-01-2010, 11:51 AM   #19
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Default Re: Mallory tech answer to coil/ballast ?

Just a few comments....total watts dissapated is divided between ballast resistor, coil, and point resistance....without a ballast resistor on an ignition system that originally had a ballast; the coil now has to dissapate 4X as much energy because it now has twice the current thru it AND twice the voltage across it! Probally its life is ending soon!
Also the current flo is somewhat less that DC resistance calculations because the coil has DC resistance but also has AC impedance which means a coil will oppose any change in current. So a coil opposes the initial current flo which is why we need 'dwell' to get the coil nearly saturated with current and then the coil opposes an end to current flow which is why, when the points open we have a inductive kick to produce spark....
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Old 12-01-2010, 01:27 PM   #20
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Default Re: Mallory tech answer to coil/ballast ?

Afternoon news flash !!!

Had a customer problem with poor performance under acceleration. Customer sent in coil and distributor.
I wired it up in the distributor machine , hooked it to battery power and ran it for a period of time watching the output with a single test plug. Primary resistance was 1.5 ohms and secondary was 7,000 ohms .
Heres what happened after 30-40 minutes !! Secondary resistance now shows "open" (still had spark but very weak). Brand name is secret to protect the innocent !!!
Chinese parts suck !!!!

To say this one got hot would be a understatement, oil is everywhere !!!!!
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