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12 vs 11 or even 10 cylinders

Discussion in 'Vintage (thru 365 GTC4)' started by 275gtb6c, Oct 1, 2009.

  1. 275gtb6c

    275gtb6c Formula 3
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    Driving the old bangers with huge and/or many carburettors is nice but too many times I had to change the spark plugs of some of the cylinders while after starting up 1 or 2 won't fire. My question is, what is the best procedure to prevent the plugs to become black?

    My procedure (with most of my cars having 3/6 big carburettors) after a couple of weeks not driving them is pump the gas pedal 2-3 times full, start the electric pumps (sorry, I have them...) and than without touching the gas start the engine. Slowly most of the cylinders will fire. If you ask yourself "are they running all", you can be sure they are not! I used the wet finger trick to check which one is not working, but an IR meter saved burned fingers. Sometimes after driving the first 10 km they come alive all 12, but quite some times you have to change 1-2 plugs. Fully black, put in new ones, problem over. Sad that always the hard to get ones have to be replaced...

    Any tips and tricks in this? I heard quite some cars running on 11 (or less!), where the owner doesn't had a clou that some where missing. That of course is the easiest solution.

    ciao
    Oscar
     
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  3. JazzyO

    JazzyO F1 World Champ

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    :)


    Onno
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    If you are presently running a standard technology spark plug (e.g., Champion RN6YC or NGK BP8ES), have you tried something a little more fouling-resistant and/or slightly hotter -- NGK BPR7EIX or even NGK BPR6EIX? I don't think the judges will know ;)

    What plug are you using now?
     
  5. Napolis

    Napolis Three Time F1 World Champ
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    If you want to no longer have this problem there is something you can do.

    Mount an electronic ignition system using your original rotor and points or if you want to be able to fire your plugs even if they are sitting in oil mount a full electronic ignition system.

    In Dino Competizione we've done the former.

    In 0846 we've done the latter.

    The cars are much more drivable.

    If you want to suffer you can always remount the original system.

    If you keep the original system:

    Before starting the car remove the spark plugs.

    Gently warm the engine with an electric heater and fan.

    Tow the car for 5 minutes to warm up the oil.

    Put in the starting spark plugs.

    Start the motor as you've described.

    When the oil is off the peg gently rev the motor up to 2.5K and back for five minutes.

    Shut the motor off.

    Remove the starting spark plugs and replace with running plugs.

    Start the motor. Rap the throttle to 4.5K and set off.

    Do not let the revs go below 3K.

    As soon as you can run the motor at at least 6.5K for at least 5 minutes.

    Don't worry about the flaming muffler packing that comes out of your 275's pipes you really don't need it.

    Enjoy.
     
  6. Napolis

    Napolis Three Time F1 World Champ
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    Very true.

    We use plugs that are used in GP racing Motorcycles.

    Beaucoup coin, especially in our cars that use 24 of them but they really help.
     
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  8. 2NA

    2NA F1 World Champ
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    #6 2NA, Oct 1, 2009
    Last edited: Oct 1, 2009
    ROFL!

    I spit my coffee when I read this.

    No problem with plug fouling there! :D

    I agree that an electronic ignition upgrade and some better plugs would help the problem.
     
  9. 275gtb6c

    275gtb6c Formula 3
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    Jim, :)
    well, you also can install a Chevy small block!

    ciao
    Oscar
     
  10. Napolis

    Napolis Three Time F1 World Champ
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    #8 Napolis, Oct 1, 2009
    Last edited by a moderator: Sep 7, 2017
    If you go that route you can use 4 of your Webers.
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  11. ColdWater

    ColdWater Formula Junior

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    This looks exactly like the shop manual for some of the English cars I've owned, except that it would be "sparking" plugs.

    Oscar, don't you want to start the electric pumps before you pump the throttle ? That's my process, otherwise there might not be much gas to pump. In theory, an uneven initial spray of fuel could foul some cylinders but not others.

    Agree with NGKs, for some reason they just work better.
     
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  13. SCantera

    SCantera F1 Rookie
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    Oscar,

    My experience with "over" carbed cars fouling plugs was cured by using the right plugs. For years Ferrari dealers would install Champion plugs. They just don't work on carb cars. Get a hotter NGK plug......maybe a BP6ES..... Although I certainly agree with Jim that an electronic ignition will alleviate the problems you might first want to try a cheaper and easier solution.

    My problems were with a carbed Boxer so this is limited advice. I don't have the same problems with either my Dino or GTC.
     
  14. Ed Niles

    Ed Niles Formula 3
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    Oh Jim, Jim, Jim! You brought me my chuckle for the day! Having had a few of those old smoke pots before NGK's came along, I can only say it's a slight exageration. VERY slight.
     
  15. f308jack

    f308jack F1 Rookie

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    I agree with this remark: there are several reasons, but for me the main one these days is that modern fuels don't age very well. If you're going to squirt some raw fuel into that throat it may as well be fresh.

    Jim,

    Priceless, expecially the part where the foam packing of the mufflers starts to come out the pipes. By the time you changed 24 plugs on a V-12 with twin ignition, you can start right back at the first one, as the engine will be cold again.
     
  16. thecarreaper

    thecarreaper F1 World Champ
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    I NEED A JOB
    i would think you would first run the fuel pumps abit to prime the fuel bowls.

    then 2 full depressions of the throttle.

    next, open throttle to 1/2 way to allow more air in , and turn the car over.

    as it starts, carefully open the throttle more to idle the car up, being careful not to flood it with the accelerator pumps.

    now gently warm the engine , before thrashing the car!

    they will start with a slight " ver-rooom " this way, every time !
     
  17. ColdWater

    ColdWater Formula Junior

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    Well said, this is my standard operating procedure for any car with Webers. But some respond better to cranking with the throttle closed rather than halfway, followed by a few ginger taps to keep the idle going once it kicks over. If it doesn't start right off, avoid the temptation to pump the throttle repeatedly. Just try cranking briefly with different throttle openings, allowing the starter to cool a little between attempts.
     
  18. malcolmb

    malcolmb Formula Junior
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    My 275 starts with a vrooom using the throttle half open technique, and doesn't foul the NGKBP6es's. I have electronic ignition triggered by standard points. It has been a LONG time since the mufflers had any foam stuff inside, which is good as it just spoils the sound..Malcolm
     
  19. tongascrew

    tongascrew F1 Rookie

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    Here's another idea. Do what some prewar Bugatti drivers did. Before starting the engine,drain all the oil into a pan. Put the pan on a stove and ,using a thermometer, warm the oil up to the required running temp, pour it back into the engine and start it up.Then breath deeply of the exhaust savering the perfume of Casteroil eminating from the tail pipe. just one man's opinion tongascrew
     
  20. Ferraripilot

    Ferraripilot F1 World Champ
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    +1 for using the points to fire a couple high voltage electronic ignition boxes. This upgrade makes all the difference in the world in carb engines and the boxes are failry easy to hide. Not surprisingly, I have seen tons of these setups in Daytona engine bays. If you decide to use something like MSD boxes, it would be a good idea to go 1 heat range spark plug colder to prevent any detonation/preignition at higher rpm as the spark from one of these boxes is huge and will not foul plugs
     
  21. IanB

    IanB F1 World Champ
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    #18 IanB, Oct 4, 2009
    Last edited by a moderator: Sep 7, 2017
    +1 easy to hide the boxes on the cabin side of the firewall, no change in engine bay appearance.
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  22. 275gtb6c

    275gtb6c Formula 3
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    #19 275gtb6c, Oct 5, 2009
    Last edited: Oct 5, 2009
    The sequence is of course first pumps and than the throttle, sorry for that. The NGK's 7 are installed BTW.
    Thanx for the advice about the electronic ignition boxes!

    Carreaper, if I do this, mine wont start!
    next, open throttle to 1/2 way to allow more air in , and turn the car over

    SCantera, yep I will try the NGK 6's, but what is the downside of taken a hotter plug?

    IanB, nice solution, but hey, I am too much a purist, even uninstalled the Dinoflex from my Dino....(that was sh**tty anyway)

    ciao
    Oscar

    ps MM2010 subscription starts soon........!
     
  23. SCantera

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    #20 SCantera, Oct 5, 2009
    Last edited by a moderator: Oct 6, 2009
    Oscar, In my carbed BB512 I found the hotter NGK BP6ES resulted in less fouling than the cooler 7s. The downside of the hotter plug might be in a lot of very hard driving.....like at a track event. You can always check the color of the tips if you are concerned about using a hotter range plug. Go to the NGK site to get more info.

    I agree with the others about the electronic ignition systems. But changing plugs might be the easy way out.
     
  24. MiuraP400

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    To me it sounds like your carburetors are not set up perfectly. They are close but not quite right. First I would check the idle mixture screws to make they are right. Usually it is not that easy. More often it is the idle jets that are not correct. In your case I would expect them to be to rich. I have also seen some sever cold starting problems caused by worn out throttle shafts. If the shafts are worn out, then your mixture will vary a lot at low throttle openings. Usually the mixture tends to be a little on the rich side to compensate for the air leakage through the throttle shafts.

    I would also suggest trying NGK 6’s too. The down side to a hotter plug is that if you go too far you will have pre ignition problems caused by the electrode glowing. This will light the mixture before the plug does. Listen for detonation noises from the engine or check the plugs after a couple of hard acceleration runs. If you are having pre ignition / detonation issues you will see little balls of aluminum on the ceramic. If you find some, it is your piston getting destroyed. Go back to the colder plug ASAP. Note modern plugs have a much wider operating range than old plugs so they are a lot more forgiving. I have used 6’s and 7’s in C and D-type Jags with no issues. In one case I have even seen 5’s used without any issues, so I believe 6’s are safe for your car.

    Personally I am old school too. I run points and coils in my vintage cars, no electronic ignition systems.

    Cheers Jim
     
  25. Motob

    Motob Formula 3
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    We use NGK 6's in every type of car except for full on race cars that we put 7's in.
     
  26. 246tasman

    246tasman Formula 3

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    +1
     
  27. Tinbender

    Tinbender Formula Junior
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    Brian,
    Do you use the standard plugs or the IX's?
    Thanks,
    Terry Philips
     

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