Understanding Backfire
 

Long story short,

I just recently replaced my stock AC Delco sparkplugs with some "slightly used" (longer story) Splitfire plugs. In order to prep and clean my Splitfire plugs a bit, I used some WD40 and some Carb and Throttle Cleaner. I then gapped the Spitfire plugs to match exactly what the ACDelcos were at.

I pop all 8 in, and try to fire it up... it takes a while but doesnt catch. After pumping a few times it finally catches, but VERY rough... only to POP loudly and die. This goes on a few more times but never gets better.

Finally I decide to just replace the old ACDelco plugs back in.. and sure enough, it fires right up, with no problems.

So what caused the backfiring? Could it have been the slight moist residue from the Carb cleaner fluid still in the "spark zone" of the Splifires? Or could this have happened if one or two plug cables were not "snapped" in all the way?

Re: Understanding Backfire
 

I've heard the Splitfires are not all they're cracked up to be.

Re: Understanding Backfire
 

I've heard the same thing about the splitfire plugs. I've had mechanics and parts store guys tell me that OE is better than they are

Re: Understanding Backfire
 

Well to be frank, I've run Splitfires for quite some years now and this is the first time this has ever happened to me. But this IS also the first time I've ever tried a gap of .050 as opposed to my normal .034 gap. I went to the bigger gap because a mechanic suggested I had to do so since I have such a hot running HEI distributor.

While on the subject of plugs, has anyone heard of these, or tried em?
http://www.pulstarplug.com/

Re: Understanding Backfire
 

I've heard good stuff about the E3 plugs, but never tried them. May try them on my new car

Re: Understanding Backfire
 

I haven't heard anything good about the Splitfires, or Bosch. I put AC Rapidfires in my truck back around '96. Still in there today & I've never pulled one. Granted, I've only put about 13K miles on them, but they have been trouble free.

Re: Understanding Backfire
 

Sounds to me like a couple of them are no good. Take an ohm meter to them and see what they read out.

Re: Understanding Backfire
 

the .050 gap may well have been the problem too.
I've run them, and on a small engine, there was a huge improvement in MPG, and a bit in performance measured by a G-tech thing.