Spark plug advice

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cwkerr007

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After upgrading to gm hei coils and modules I'm very happy with results on all my motors and 0 problems, but I am currently building a magnum 5.9 eq heads and was thinking about "Well I upgraded the whole ign but I'm still running the same plugs! I'm happy with the perf of the ones I'm using but should I be running different plugs?? Never thought about it till I was ordering the plugs for this motor. So I'm in search of a spark plug guru to put me on the path of plug enlightenment there has to be one out there
 
Havent put plugs in the 5.9 magnum with eq heads as was stated in the opening the bottom end is oem and the question is if the ign has been changed to HEI then should the heat range of the plug change ??? Should the type of plug change platinum,irid,oem,or no need to ????
 
put some plugs in it and run it for a while and post some pictures so we know whats going on then we can see id your heat range , timing and tune any other way id just guessing . every engine is different .
 
jimjimjimmy said:
put some plugs in it and run it for a while and post some pictures so we know whats going on then we can see id your heat range , timing and tune any other way id just guessing . every engine is different .
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your right and from the other motors I've done this to I've only changed plugs in 1 and it was just to put some platinums that were given to me. The champions that were in it were clean but the previous motors weren't magnums and I thought maybe someone had already experimented with this since I haven't bought the plugs yet I was looking for a starting point.
 
I have trouble doing pics for projects because it takes me a long time to do the job to begin with cause it's just me and the dog and my wife and you can guess which one is more help lol I had my leg amputated 5yrs ago and my elbow won't bend on my left so it will probably be a month before any pics of this motor running skipping jogging or any other of those things lol
 
Without seeing your plugs, you may just have to increase your gap. .045 if I'm remembering correctly.
 
Kendog 170 said:
Without seeing your plugs, you may just have to increase your gap. .045 if I'm remembering correctly.
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I'm sorry I'm not explaining my situation properly. I have built a 5.9 magnum and I haven't started it up yet, it is on my engine dolly with the manual trans all together and I am at the point of putting the dist in and the plugs. I haven't bought the plugs YET so the diz is from my LA 360 proven good carb is from my 440 holley proven , so when I crank it I thought I would pick the brains here for a starting point of what plug to start with cause although I am well familiar with doing this with the la and the rb motors I haven't done so on a magnum and they are different designed plugs so I was looking for someone running hei on a magnum to make sure I'm not running to hot. I'm running the gap at 042 so if anyone is running magnum with hei have you had any plug issues???
 
cwkerr007 said:
I have trouble doing pics for projects because it takes me a long time to do the job to begin with cause it's just me and the dog and my wife and you can guess which one is more help lol I had my leg amputated 5yrs ago and my elbow won't bend on my left so it will probably be a month before any pics of this motor running skipping jogging or any other of those things lol
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To bad we didn't live closer , i would enjoy helping you work on your car . Good luck , there's lots of sharp people hang out here willing to help .
 
I would start with the ole Champion rc12yc. I've tried rc9yc and they were too cold. Also tried NGK and they were okay, but went back to the Champion rc12yc for my Magnum.
 
Heat range is a '5' in NGK for your engine. Rarely is there a need to change that, & not in this case.

If you want to run bigger plug gaps, use Plat or Irid plugs. The smaller centre electrode requires LESS arc over voltage & is therefore less likely to misfire. Use 0.060" gaps or more. Another Plat & Irid advantage: they are very hard metals. The electrodes therefore stay sharper over time in the engine. Nickel/steel elecrodes in conventional plugs are softer & will round off from spark erosion. The rounded electrode requires more spark voltage & can lead to misfires.
Others will reply to this & say you do not need 0.060" gaps. They have yet to explain how we evolved from 0.010" gaps of magneto ign in 1915, to, over the years, 0.080" gaps. [ some GM engines ran 0.080" gaps from the factory; they could have run 040....but didn't ]. Getting bigger....not smaller.
 
cwkerr007 said:
After upgrading to gm hei coils and modules I'm very happy with results on all my motors and 0 problems, but I am currently building a magnum 5.9 eq heads and was thinking about "Well I upgraded the whole ign but I'm still running the same plugs! I'm happy with the perf of the ones I'm using but should I be running different plugs?? Never thought about it till I was ordering the plugs for this motor. So I'm in search of a spark plug guru to put me on the path of plug enlightenment there has to be one out there
Click to expand...
If you're happy with the ones ya got, why change?
 
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