Can someone explain why this is not a good combination. What are the problems and causes? Why are performance plugs recommended for use with stock ignition only?

 

LT1LE,

Who is recommending aftermarket plugs with stock ignition only?

 

If a company says to only use their plugs on stock ignition, I wouldn't buy them because they are probably crap.

 

Sorry guys , maybe I am mistaken. From everything I have read on here before about mixing AC Rapidfires with MSD stuff I am confused.

 

My rapidfires had instructions right in the box saying they were for stock ignitions only. I tried them with my msd6a and jacobs coil. ran like crap. Used the same set with my stock ignited chevelle and they work fine.

 

I don't know much about spark plugs, just that when I replaced them with a regular set of bolts, the engine didn't run?
They're just there to plug that hole right?

Just kidding.

But really, I am running rapidfires with my new Crane Hi-6 (and stock coil for now) and it runs fine. Are there greener pastures with other plugs or what.
I have noticed though that at night, I can see the ceramic insulators on the plugs glowing with the spark pulses. It kinds worries me. This can't be normal.

 

I have RapidFires and full MSD ignition. Works fine for me ?!?

 

The jacobs ultracoil is a variable voltage/amperage unit. It uses the spark plug as a resistance sensor. This is probably why I had so much problem with them. It's calibrated for normal copper plugs. The main reason I responded to this post was because of the instructions that came with my rapidfires. These weren't bubble packed rapidfires but ones in the cardboard box. And they did say stock ignition only, plus the "don't re-gap" crap.

 

yeah, thats what I thought. The rapidfires say for use with stock ignition, and some people have had trouble. What I want to know is why this happens. Is this only a problem with platinum plugs? Is it only with AC Rapidfires? Basically, what kind of compatibility issues do I need to know when buying spark plugs, plug wires, modules etc.?

 

One more thing. I tried splitfires once and they worked fine. Maybe even helped a little bit. However, once they were worn I never bought another set. If they really did do something it wasnt enough to be worth the money.

 

I agree. I'm not planning on buying any expensive plugs either. I just wanted to know why certain plugs can't be used with certain iginition. All my plugs are fouled from previous problems which are now fixed. I will either replace them with standard AC Delcos or some NGKs. I have Accel 8.8mm spiral-core wires.

 

I use a Holley Anihilator ignition system, MSD 8.5 wires and plain ordinary AC R43TS plugs. I have them gapped at .050"