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Ignition facts ??

Discussion in 'The Hokey Ass Message Board' started by GMC BUBBA, Oct 22, 2012.

  1. nukeman
    Joined: Mar 17, 2007
    Posts: 131

    nukeman
    Member
    from Michigan

    Sure he can, he can do anything he wants to. All he needs to do is put the second set of points at 225 degrees for example. (he wasn't sure about the 180 thing anyway)
    Although possible, I don't see any advantage for the extra complication except that you would have half the wear on the points, but twice the number of points to replace.
    Now if it was wired to two separate coils, with a dual input distributor cap, it still wouldn't be worth the hassle.

    (subscribed as well)
     
  2. With the dual points properly phased as described above on a 4 lobe distributor cam, each set of points can be adjusted to run a greater amount of dwell for better coil saturation. More important than the dwell setting though is making sure that each set of points opens alternately every 45 degrees.
     
  3. 4woody
    Joined: Sep 4, 2002
    Posts: 2,103

    4woody
    Member


    Dolmetsch & GMC Bubba: 2 of my favorite Hambers in the same post. I know I'm gonna learn a bunch.
     
  4. nukeman
    Joined: Mar 17, 2007
    Posts: 131

    nukeman
    Member
    from Michigan

    A lower impedance coil would saturate faster as well if that was the issue, but since the guy that brought up modifying a stock Delco distributor to dual point just seemed to be toying with "what ifs" in his head, and since all parts of an ignition system must work in harmony with each other and the engines performance goals, I don't see a need to continue down this road...
    Even if you had to modify another dual point system to fit your particular engine, it would give you a better starting point than starting from scratch.
    Although, you will never see improvements in performance without those guys who can't resist the urge to tinker with stuff. (us)
     
  5. 63 Avanti 3137
    Joined: Dec 23, 2010
    Posts: 160

    63 Avanti 3137
    Member

    Waiting as well, but in no hurry, and I want to thank GMC Bubba for taking this time, letting some of us listen and learn from the conversation as everyone waits for his next installment.
    Well done Sir.
     
  6. Candy-Man
    Joined: Mar 21, 2006
    Posts: 1,713

    Candy-Man
    Member

    Waiting as well ???
     
  7. And then came the "red boxes" and here we go! I have noticed an increse in driveability with a 6a on many cars.

    And I understand compression x RPM is the other big factor, and with my huffed gasser, I too will stay tuned........
     
  8. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    Two issues here the higher primary voltages ( at rpm) and the reversing polaritys the coil current rises and the reversing primary allows a much faster rise time as polarity is reversed ..... put the two facts together and thats what makes a mag so hot at 9000 plus rpm...
     
  9. Sorry for going astray from this topic, BUT!!!, what kind of Aircraft Ignition Man is he. Aircraft have Mags as a fail safe way to keep the engines running in case of and electrical failer that would make a coil fired engine stop running. Also, planes have two Mags, just in case one fails during flight.
     
  10. Here's some of the history and operation of magneto ignition systems. Scroll down a bit to the Aircraft section and it explains a bit about the use of dual magneto systems. They not only provided a back-up but were also used to fire a second spark plug in engines with two plugs per cylinder.

    http://en.wikipedia.org/wiki/Ignition_magneto
     
  11. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    Yes we will do another two day ignition class sometime this winter.....you need to call the shop and have Peggy put your name on the list....317-487-9460:eek:
     
  12. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    Ok had some time after work today and will do some PART-2 Stuff etc....

    Heres what we said in part one :

    Part 1
    I get this phone call each and every day.
    Goes like this :

    Jim I have a xxx engine going in a hot rod build up and I need hotter spark !!

    Q=Well why would you need hotter spark ???
    A= Well I have a xxx engine and three carbs with a 505-43xd2 camshaft in a 1927 Ford T coupe
    .Q= That sounds cool what rear axle do you have ?
    A= Beats me came out of a Ford truck of some kind.
    Q=Is the car running now ??
    A= No I am just putting it all together .

    Now lets come up with a group answer to all the above.

    99 % of the time you don’t need hotter spark you just need reliable steady spark. In most cases a stock ignition system tuned will supply more spark than you would ever possibly need.
    A good example would be a standard Delco ignition system on lets say a 1968 350 Cubic inch engine with a four barrel carburetor. The stock coil has a max output of 20-25,000 volts and the engine on a good day needs approx 5-8000 volts to ignite and burn the air fuel mixture. Accelerated to mid range of 3000 rpm with a load the ignition demand might jump to 10-12,000 volts leaving a reserve of approx 15,000 volts.
    This reserve would allow the ignition to function ( in stock form) for a long period of time or a lots of miles etc.

    A couple of ignition facts:

    1= If a stock ignition system was using 6,000 volts at idle with a stock ignition coil and we stopped and changed the coil to a Super stock 40,000 coil and retested , the engine would still need and use 6,000 volts.
    The only reason for a larger output coil is to increase the reserve voltage if ever needed.
    2=A hotter spark and bigger coil wont fix a over rich fuel mixture..

    Reasons for the need for larger reserve voltage in Can We talk part # 2 ….Stay tuned…



    Why is a question that if i had properly explored the word " why" i could have retired many years ago. I feel that in hot rodding any vehicle we must set down and plan each and every change using the why theory.

    Example : When my son was in high school his best friend bought a used 78-79 Corvette in pretty good shape. The first problem was that many of his high school friends could kick his butt from red light to red light. He came to me one evening and said i am going to buy a xxx45xx camshaft, lifters , alumin intake and holley carb and would like to use your garage to install them and need some help.. My answer was why do you want to do all that and of course we all know the answer , the marketing hype says it will make me go even faster !!!!!
    Now lets think this over , he has a corvette engine ( pretty good design), a HEI ignition system ( again pretty good design), a quadrajet carb ( more national records set with a quadrajet than any other carb), engine makes some good power and revs up pretty from the factory.
    The problem in my mind isnt any of the above, the problem is in the factory 3.08 rear axle gear ratio.
    My suggestion was wait , dont spend a dime , lets find a 3:73 ring gear and pinion , give the car a minor tune up and put it in and see what it will do ! The local trader paper found us a good priced 3:73 ring and pinion and we bought it right away.
    After installation the boys took it out for a test drive and come back to the shop with pure smiles . WOW was all they could say !!!! The following week they took their friend with the 455 Olds trans am ( another 3:08 final drive) out to the local interstate and beat him pretty bad.
    My point is that many times we throw away much better parts than we install.
    This is especially true with ignition and ignition parts.!!!!

    Now lets discuss the reasons for adding increased spark output ......
    You may need more spark for the following reasons:

    • Resistance ( wear)
    • Air fuel ratio ie: rich-lean
    • Heat- cold temperature
    • Cylinder pressure (compression)
    • Camshaft change ( compression)
    • Exhaust Headers..

    We must all agree on a couple items here , the system is assumed to be in good working order ( or tune up), good compression, spark plugs wires etc.

    1- Ignition system resistance ...... System must be properly designed with correct resistance parts. I can tell you how many times i talk to a customer regarding a problem to hear him say ( had this one today) "Well i guess it could be the ignition coil , its a XXX that i bought at a swap meet a few months ago"
    If the system is set up for 1.5 ohm ressitance coil and you are using a .5 ohm unit , it WILL burn every thing up due to a incorrect amount of amps!!!!
    Plug wires must be clean and have good insulation on them.
    Spark plugs wear and offer increased needs for spark. The wrong spark plug for your engine can cause increased spark levels as well. In doubt ?? Use the factory plugs for your engine !!!


    more to come .......................................................
     
    Last edited: Nov 1, 2012
  13. olskoolspeed
    Joined: Mar 2, 2009
    Posts: 476

    olskoolspeed
    Member
    from Ohio

  14. junk yard kid
    Joined: Nov 11, 2007
    Posts: 2,719

    junk yard kid
    Member

    I have a car that was haveing all sorts of problems. Kicking back on the starter, would push oil out of places with sustained high rpms, bad fuel economy. I did a compression check which turned out fine. Then i pulled the cap off the mallory unilite, I found burnt plastic and blackened brass/copper and a big gouge in the side of the cap. So i decided to do redo the whole thing. I put a bubba dizzy in it, and stock coil ballast and wires. I had the wrong plugs in it (short when i needed long). What a world of difference. No more pushing oil out of the valve cover or the dipstick. I dont know exactly why though as the bushings in the mallory didnt feel bad. Thank you bubba
     
  15. belair
    Joined: Jul 10, 2006
    Posts: 8,697

    belair
    Member

    Subscribed. I'm too dumb to learn much, but I'll take what I can get. Thanks for blowing away the smoke and hype, Bubba.
     
  16. 3wLarry
    Joined: Mar 11, 2005
    Posts: 12,804

    3wLarry
    Member Emeritus
    from Owasso, Ok

    I heart bubba...
     
    kidcampbell71 likes this.
  17. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Talking about 3.73s??!! On THE HAMB??!! What are you, some kinda trouble maker??!!:rolleyes::p
     
  18. Thanks Jim....
    That points style Mallory dist. you converted to elec. runs great in our flathead.
    Hey, we need some T shirts!!
     
  19. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    1- Ignition system resistance ...... System must be properly designed with correct resistance parts. I can tell you how many times i talk to a customer regarding a problem to hear him say ( had this one today) "Well i guess it could be the ignition coil , its a XXX that i bought at a swap meet a few months ago"
    If the system is set up for 1.5 ohm ressitance coil and you are using a .5 ohm unit , it WILL burn every thing up due to a incorrect amount of amps!!!!
    Plug wires must be clean and have good insulation on them.
    Spark plugs wear and offer increased needs for spark. The wrong spark plug for your engine can cause increased spark levels as well. In doubt ?? Use the factory plugs for your engine !!!

    LETS START AT THE DISTRIBUTOR.....Most factory distributors were very good even for todays standards. The old cast iron units were made to run forever so lets again assume the old factory distributor is cleaned and lubed and set to factory specifications.
    The distributor triggers ( or times) the spark build up at the ignition coil and again we will assume the resistance of the primary is up to factory specs as well.
    Once this spark leaves the ignition coil it travels to the distributor cap ( good quality with brass contacts, not off shore reprocessed strohls beer cans !!!)the spark then travels from the rotor thru a predetermined air gap and into the connection and spark plug cable traveling to the spark plug.
    In the cap the air gap provides some resistance as well as the coil wire , the air gap is the most important and actually has become a emission issue with the amount of radio interference that can be generated by this gap. It will also eat up some of the spark output ( usually take approx 1000 volts to bridge this gap.) may be measured on a ignition scope by grounding the distributor terminal to a ground and observing how much each cylinder actually needs...
    The ignition cable typically will offer 1000-2000 ohms ( per inch) and is in effect another emission devise. If all vehicles used solid core cable (vs todays carbon) we wouldnt have cell phones etc. I remember in the 60s when we first got a TV , i could tell whose car went by our house ( which was in the country) by the stactic and level of interference it had on the TV ( we actually had three channels back then) I learned to hate this one guy as their 1956 Ford runined Mighty Mouse each and every day !!!:D The guy down the road in a 1958 Chevy didnt seem to be a problem.
    Now on to the spark plug. Spark plugs were non resistor and used a solid conductor all the way thru and offered very little resitance, where as today the plugs are all resistor plugs with a resistive carbon core offering a slight resistance to current flow. Resistor plugs today are very good and i suggest using them when ever posible.
    Spark plug heat range refers to the ability of the plug to transfer heat to a cooler surface .
    Spark plug gaps are per engine design and should stay close to the factory settings.
    There very little to be gained by making a gap wider , unless we need more spark duration like in a very lean ( hard to fire) emission engine.
    Making the gap larger increases the spark output needed to fire the combustion air fuel mixture. One we see all the time is a larger plug gap making the output larger and then three carbs running a rich air fuel making it require less than normal.

    Rich = lower demand and lean= higher demand.
    It is harder to ignite a lean mixture due to the fuel mixture ( fuel atoms) being thinner ( not as many) making spark and flame travel tough to maintain. (hence the need for multi-strike and other electronic long duration ignition systems)
    If you install a aftermarket plug and it improves anything at all ( and they may) its based on the fact that you had a problem to start with and accidently fixed the problem.
    I recall working for a fleet nad had a few trucks eating spark plugs in a few miles . After fighting this for some time a salesman came in and gave us some xxx brand plugs to try and bingo , the problem was gone.!! Years later doing some plug work with a large company i realized alll he had done ( again by accident) was to give me a very different heat range needed because we had changed the factory of these on road trucks to in town delivery. Was just a matter of getting the correct heat range of the plug in the right engine.....:)
     
  20. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,074

    Truckedup
    Member

    Allison 1710 , the Griffin 2240 ,both V-12's and the Wright 3350 radial,combat WW2 engines, had one magneto but 2 plugs per cylinder like most aircraft engines.
     
  21. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    One more discussion ( with some homework for everyone) for this evening .
    One of the ways to increase spark needed to ignite the air fuel mixture would be to change the compression of the engine. Lets say your engine is a 8-1 smog engine right out of the wrecking yard using the 5000 volts at idle to ignite the air fuel mixture.
    So we overhaul the engine and change the pistons ( or heads or both) and make this engine a 10 -1 engine . Now the engine might need 7000 volts or more .
    So lets discuss compression.
    A good gauge is to perform a running compression test on the engine ( a great way to catch some cheating in some racing classes).

    1-Do a static compression test by cranking the engine with a gauge in one of the spark plug holes with igntion disabled and throttle blocked open.
    engine sealing
    Lets say we got 150 psi
    2-Now inable the ignition and start the engine . The gauge should read approx 50% or 75 psi running.
    engine breathing
    3-Now snap the throttle and the reading should be approx 80% of the static reading.
    valves and camshaft

    Now get some readings on that hot rod and lets talk about it???????

    wps.prenhall.com/wps/media/objects/6568/6725731/.../Chapter08.ppt
    A Jim Linder book with this chapter in it.......
     
  22. CodeMonkey
    Joined: Sep 13, 2012
    Posts: 92

    CodeMonkey
    Member
    from Moline IL

    Way too cool - or is that hot... making my head hurt.

    Spent way too much time, even in high school, arguing with guys who thought if a little is good, a lot is better and too much should be just about right. Cams, carbs, compression, spark. I seriously doubt that most of them get it today.

    Subscribed. Not sure why I didn't see this one before.
     
  23. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    I belive point float would also be harder to get with a 4 lobe vs an 8...


    Thanks bubba, i love this, please tell me we are going to get into advance curves!!!
     
    Last edited: Nov 1, 2012
  24. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member


    Yes i will add in advance curves as we go..
     
  25. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    So you see there is a need "sometimes" for higher spark output.

    Ie :You may need more spark for the following reasons:
    Resistance ( wear)
    Air fuel ratio ie: rich-lean
    Heat- cold temperature
    Cylinder pressure (compression)
    Camshaft change ( compression)
    Exhaust Headers..

    All of the above would be a secondary resistance factor.
    There are three kinds of voltage in a ignition system:
    1=Voltage available- Voltage available in a ignition coil Lets say 30,000 is a good common number
    2=Voltage required- Voltage required to ignite the air fuel mixture. 5,000-8,000 volts on a properly tuned engine
    3=Voltage reserve-The voltage not needed thats saved for pulling a load, snap throttle etc. In this example the reserve would be 22,000 volts.

    This 22,000 volts would last for many years on most cars "properly maintained".
     
  26. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,210

    theHIGHLANDER
    Member

    "What is well thought through, no matter how simple it may be, is perfect."

    "Whatever is rightly done - however humble - is noble"

    "Accept nothing nearly right or good enough"

    Sir Henry Royce

    I just think it truly applies to this 'Bubba so I tossed em up there. Thanks for a great topic.
     

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