Two plugs - Neccessary?

[John Ferrell]

Thanks for confirming my suspicions!
The only dual ignition engines that I am aware of are those in highly critical applications, full scale airplanes and emergency services. My personal experience with full scale has been that the second spark plug only makes the troubleshooting more difficult. I believe the whole idea of redundant ignition is a concept whose time has past. There are twice as many things to fail. 

I knew a fellow who was preparing a van for his handicapped son. The law at the time required dual, isolated batteries. The mechanics acknowledged that the isolation electronics were the least reliable part of the van. That was many years back, I hope it is better now.

John Ferrell    
http://DixieNC.US

  ----- Original Message ----- 
  From: Grow Pattern 
  To: discussion at nsrca.org 
  Sent: Wednesday, April 20, 2005 7:07 PM
  Subject: Two plugs - Neccessary?


  I made a dual plug head for the OS 1.40 and for the 1.60. I also ran two Mintor 1.60's.

  I know before I type what follows I may well draw some fire, but after two years of using twin-plug-heads on different motors I am personally convinced that they are a total waste of money and time.

  If you are using a twin plug head to fix a "problem" there is probably a better fix!. 

  I went through over 60 plugs of all types. I still have a can-full of them in my van. Constantly, I saw the lower or rear plug fail, It always ran better with the center plug working but you had to reset the carb. One argument is the engine keeps going if you lose a plug. The reality that I experienced is that there was a big loss of power and often overheating when one plug went out. Twin plugs change the ignition timing of the engine. Two plugs of the same type, A-3 "F"etc. or mixing rated plugs all interfere with the timing and design of the motors combustion.

  Of course there are a whole bunch of folks that are happy with two plugs and are convinced that they are the way to go. I say enjoy and I'm glad for you, really!

  My 1.40's, and I say mine whether I still own them or not, run like watches on one plug. My OS 1.60's run great on one plug. The FI or Mix-carb versions, it makes no difference, if you set the carb correctly and use the right volume of pipe, they run great.  I literally  gave up on my 1.60 Mintors, especially after I was informed by the supplier that I did not know what I was doing with 2-cycles!  I acknowledge they could well have been right, but there was no available information to fill the vacuum of why and what was the reason that they did not work. (Ironically enough the factory agreed basically with my findings and changed the guts of the product) The upgraded piston and liner ran better but they still kept killing plugs at a much higher rate than a single plug set-up. 

  But I digress. The twin plug does give a lower idle and does help through transition on a tuned pipe. However if your engine will not run at an acceptable idle on one plug something else is amiss. For example. wrong plug, wrong fuel, idle mixture is off, bad bearings, tight ring/liner etc. Similarly on transition problems. I have noticed that quite a few so called tuned pipes do not have much of a tapered cone to the main body of the pipe. Mix carbs and double plugs might get you through these issues, It's your choice.

  Regards,

  Eric.
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