Ok here is the problem... Las year in December I Replaced my Defective TR55's (inside insulator crak problem) with new TR5's pluss I added an MSD6a and Scorpion 1.7 RRs with Beehives and new Valve Stem Seals etc etc...

Well It ran a bit Rough from the begining but it picked up a really nice amount of torque down below so I figured it was a result of the whole set up...

Well a couple of months ago.. it began to misfire a couple of seconds after start up when cold... It would start really smooth then... it would begin misfiring. It would continue to misfire untill it would reach normal temp... above 160 BUT... only under very light throttle... like 15 percen or less.. or very light load. as soon as I would give it just a bit of gas it would misfire again

I pulled the plugs.. the were carbon fouled and dark... with just a very faint coat of something on them... did not looked nor smelled like oil at all... the inside insulater was fouled up with black carbon and the very tip was white... as in too hot a plug? but the carbon was black... some of them had the white part extending to the side and down the insulator... as if the spark plut was firing toward the side (the thread) as opposed to the tip.

Well I replaced them with new TR55's again and bingo problem fixed... smooth again and still running smooth...

now I was just reading

http://ngk.com/charglossary.asp?kw=R...r+race+engines


And it mentions MSD and some other capacitive units being able to fry the insite Resistor in some spark plugs...

will you guys give your opinion as for this actually happen to any of you? I know some of you guys had great results with NGK's but I have used them for three times.... Twice they crapped out on me and today I pulled #1 out and it looks like its running too cold. The whole insulator is clean but dark brown as opposed to mid grey.... It looks like its one step colder than it should be and I am wondering if my it has to do with the resistor.... maybe a weak ignition or something like that. I had those plugs for about 1000 miles and not happy with them.

I will measure the resistor of #1 first chance I get.... per website they should read about 5K ohms.... If I see something like 30k ohms or more I will start suspecting something

What do you guys think?


Marvin

 

The hotter ignition can sometimes cause a need for a slightly cooler plug try the Autolite 104s some of the aluminum head guys run them for nitrous and say the 106s are right for NA where the iron head guys have found the 106 to be a tad too hot(we "should" use the same plugs per GM), this suggests to me the 104 is slightly colder.
Really though ignition "upgrades" are a waste unless you are planning to boost or spray. By the time these cars were built the OEMs were doing the ignition well for emmisions reasons.

 

Thanks bro..

Marvin

 

I also have been having the same problem with ngk's. When i install them they
work fine for a while then the ceramic part starts glowing blue, can't figure it out.