Ignition Coil Selection. |
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Posted: 22-November-2014 at 10:10AM |
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I have a friend who has a 1973 ford ranchero, the previous owner of the ranchero had a 1976 ford 460 engine installed in it. The engine has what i believe to be a 1973 ford 429 distributor installed in it. The distributor has only a single vacuum advance diaphram (not a dual vacuum advance/retard diaphram) installed on it. Recently he had a mallory unilite 502 breakerless electronic conversion kit installed inside of the distributor, so there are no more contact points installed in it. He is still using the 1973 original equipment type of ignition coil. The spark plug gap for the 1976 ford 460 engine is specified to be 0.042" to 0.046" in the ford repair manuals. The spark plug gap for the 1973 ford 429 engine is specified to be 0.032"to 0.036" in the ford repair manuals.
Someone had recommended an Accel 8140 coil to him. This accel coil has 42,000 volts maximum output and it has less resistance and more inductance than the original 1973 ford type coil. I will post the specifications for this coil below. Primary Resistance: 1.400 ohms Maximum Voltage: 42,000 V Turns Ratio: 94:1 Secondary Resistance: 9.2K ohms. Another person had recommended a mallory 29219 coil, I will post the specifications for this coil below. A third person had recommended a mallory 29216 coil, I will post the specifications for this coil below. Primary Resistance: 0.700 ohms Maximum Voltage: 51,000 V Turns Ratio: 99:1 Secondary Resistance: 8.9K ohms Inductance: 6.6 mH Peak Current: 180 mA Spark Duration: 400 uS There was also someone who had recommended an original equipment type replacement coil. I will post the specifications for the 1973 original equipment replacement ford coil below. Inductance (mH): 6.6 Minimum Primary Resistance Range: 1.50 Ohms Minimum Secondary Resistance Range: 11,000 Ohms. I was told that the maximum output voltage of these factory original equipment type coils is about 20,000 volts. Is this true? Is more voltage really necessary? Next I will post the specifications for another 1973 original equipment replacement ford coil below. This next coil is from the same company as the coil listed above, but it is a better quality and it costs a few dollars more. Inductance (mH): 6.6 Minimum Primary Resistance Range: 1.50 Ohms Minimum Secondary Resistance Range: 10,000 Ohms Next I will post the specifications for a 1974 through 1978 original equipment replacement ford coil below. Inductance (mH): 6.2 Minimum Primary Resistance Range: 1.3 Ohms Minimum Secondary Resistance Range: 9,000 Ohms I was told that the maximum output voltage for these original equipment 1974-1978 replacement coils is about 20,000 to 23,000 volts. Is this true? Is more voltage really necessary? If it is necessary, how is it necessary? Next I will post the specifications for another 1974 through 1978 original equipment replacement ford coil below. This next coil is from the same company as the coil listed above, but it is a better quality and it costs a few dollars more. Inductance (mH): 7.6 Minimum Primary Resistance Range: 1.3 Ohms Minimum Secondary Resistance Range: 8,000 - 10,000 Ohms My friend only uses this car as a daily driver sometimes and he does not use this car for any type of racing or high performance driving. Sometimes he has to rev his engine up to 3400 to 4000 RPM's when he is entering a onto a highway, but that is the only time that he revs the engine that high. So will a higher voltage/lower resistance/higher induction coil really be necessary? Also, what do you think that he should set/adjust his spark plug gaps to? I can tell you more about his engine so it will be easier for you to give answers to me: His engine has an original equipment type (stock) camshaft installed in it. His engine does not have any high performance/racing parts installed on it, he had mentioned that he is probably going to keep it that way. He sometimes has to park his car in a large warehouse-garage where their are other people working, so he needs good/low exhaust emissions out of his exhaust tailpipe. Also, If any of you know of anyone who has greatly increased the Size and CFM's of their carburetors (for extra fuel intake), due to the fact that they were adding on other high performance parts to their engine and they still have good/low exhaust emissions out of their exhaust tailpipe, (possibly due to the fact that they had added a higher voltage/lower resistance/higher inductance ignition coil), I would really like to hear your stories. Thank you for any answers that you can give to us.
Edited by dave302 - 23-November-2014 at 9:39AM |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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I'd leave the Air Fuel Ratio out of the formula on this one spark plugs are designed for the gap they'll be set at, so the ground strap electrode remains perpendicular to the center electrode through the service life of the spark plug. if an incorrect plug is gapped to cause the ground electrode to angle slightly to the center electrode, as the plug wears(electrode deterioration) the gap will change the breaker point eliminator module is definitely a good thing, and probably engineered to use the pre-1975 points type coil? have you tried hitting up Mallory for a suggestion on what coil to use for the 1976 plugs & gap? then again it's possible that the 1973 plugs & gap will be the best overall for the situation. with the difference between the .036" max & the .042" min being quite small, I think I'd revert back to the 1973 plugs & run them @ .035" ~ish those small differences in Ohms, Impedance, Reluctance, Resistance & whatever else they can come up with can make a big difference, the wrong coil may start & idle OK but won't run down the road worth a crap I'd see what Mallory thinks might work best https://prestolite.zendesk.com/anonymous_requests/new
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72 GT Ute
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14609 |
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generally from my knowledge most stock coils were around 30,000 volts, those aftermarket chrome coils were like 40,000 volts, and the hei and the big yellow accel coils were 60,000 volts. the ford coils were shorter so they may in fact be less voltage?
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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For the spark plug gaps they say to use the engine manufacturers recommended specification gap. But for racing applications they say to start with the engine manufacturers specification gap and then experiment with and closely monitor various gaps until maximum performance is achieved.
The one possible problem with this is that these instructions are usually for the 1973 and older engines that had originally came from the factory with contact points in the distributor. My friends engine is a 1976 engine, with a 1973 (small distributor cap) distributor installed on it. Edited by dave302 - 22-November-2014 at 2:08PM |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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it's a monster. I didn't have much trouble finding a place for it to fit but on a full dress big block? . 29440 IIRC works with points also 29625... 67000v, male HEI terminal and it's bigger than mine 29126... 51,000v, female socket correct for the 1973-76 Ford coil wire first application under Ford is for a 1963 390 so it works with points, and it'll fit in the stock coil bracket
Edited by Rockatansky - 22-November-2014 at 2:21PM |
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72 GT Ute
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Thank you for the answers, i appreciate it. So you are saying that you would definetly recommend the mallory 29216 coil, instead of any other coil for this engine that we are talking about above?
Would there be a big improvement over the stock 1973 original equipment coil that is on this engine now? Would this be much better than the accel 8140 coil which is rated at 42,000 volts maximum output? Is it because the mallory 29126 has 9,000 more volts of maximum output?
Edited by dave302 - 22-November-2014 at 2:31PM |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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I wouldn't be interested in the Big Box coil, I'd look for something that matches very closely to the original
if Mallory swears up & down that the 29216 is compatible with their trigger module it would be on my short list and @ 50k+ volts I think it'd fire the .045" gap to use the 1976 plugs for better emissions FWIW I was just searching around a little & found a post that states the resistance for a point fired Q-code was 1.47
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72 GT Ute
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Thank you for the information, I appreciate it.
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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I'd go along with all that. factor in cost, availability, end goal (desired plug gap) ... i'll admit that I'm not so much an ignition coil scientist, that's why I defaulted to Mallory tech recommendation since it's their trigger module in there. with all the late model re-inventing of the ignition coil for decades now, it's easy to get something incompatible HEI, TFI, wasted spark, capacitive discharge jeez just light my plugs already! ya know what I mean
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72 GT Ute
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Thank you for the answers, I appreciate it.
Edited by dave302 - 22-November-2014 at 3:04PM |
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Rockatansky
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coil output volts shouldn't have any negative effect
increasing should only make it run smoother & cleaner
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72 GT Ute
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Thank you for the answers, I appreciate it. I have always wondered why the ford motor company had never offered a performance ignition coil (even as an option) on there 1972 through 1976 engines? They all seemed to have the same 30,000 volt maximum output voltage coil. Was there something that they did not know back then? Or maybe there was some other possible reason?
Edited by dave302 - 22-November-2014 at 3:29PM |
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californiajohnny
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Thank you for the answers, I appreciate it. There is also the mallory part number: 29219 58,000 volt coil that someone else had recommended. http://www.summitracing.com/parts/maa-29219Would you think that this part number 29219 58,000 volt mallory coil would be better than the mallory 51,000 volt coil? If it is better, is it because of the lower resistance and higher output voltage?
Edited by dave302 - 22-November-2014 at 4:21PM |
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Rockatansky
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29219 looks to have an internal resistor by the Notes in the description, something I forgot to mention up above
. our Fords have a resistor wire built into the harness unless it's been removed, which constitutes an external resistor in my book ~I~ would make another call to Mallory & confirm that the final choice is compatible with both the car & the external resistor, Ford resistor wire to be specific they all look pretty much the same but they're different all else being equal, output will vary depending upon input volts and resistance will affect that
Edited by Rockatansky - 23-November-2014 at 3:08AM |
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72 GT Ute
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Regul8r
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Dave without reading this whole thread just remember the Ballast and non ballast stuff talked about in the other thread. Ensure you don't mix and match and you have the proper voltage feed.
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Carl Corey (Moderator/Event Coordinator) Contact ANYTIME!
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dave302
Senior Member Joined: 08-October-2009 Location: usa Status: Offline Points: 3171 |
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Thank you for the answers, I appreciate it.
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