AC DELCO RAPID FIRE PLUGS, WORTH THE $ ?

Overheard conversation the other day, about how well those worked in a customer's old vehicle.

Wondering if they're good for MoPar engines, such as the LA and B engines.

Thanks

Ran regular ACs in Gms at work.Mopars we ran and I run either Autolites or NGKs.NGKs in my 65 run great and its 12.5 compression street driven.Rocky

No, they are not worth the extra money. Marketing hype

I run NGK or Denso plugs in my Mopars They seem to last forever and I get them cheap from work

Gus

Get the correct plug for your motor, not the latest gimmick. I use NGKs normally, but have had good service from all different brands of conventional plugs.

My opinion is the absolute best plugs are Iridium, but in reality they are quite pricey and also not too many people are driving a ton of miles on their classic mopar. So the only advantage would be the smaller electrode is somewhat less likely to misfire.

I doubt you'd notice a difference.

That Delco design plug has more sharp edges to lower the peak KV to get the spark to start.
They have not worked noticeably better for me.

I prefer the expensive irridium alloy tiny tips, either NGK or Denso.
They both start the spark at lower KV and allow a much larger spark gap that allows a faster burn and less advance before top dead center.

I run NKG's in my MOPAR (standard type). Works fine. Autolights in a classic PU. Works fine.

Platinum plugs, OE style, in late model DD's.

The platinum plugs offer up to 100k mileage which is relevant in a DD. In a hot rod, what is the point? Plugs will usually be changed for some reason well before high mileage is reached. Heat range may be wrong. They may be fouled. Or as preventative maintenance.

Basic Champion for my old stuff.

Just dont get Bosch.Total s--t plugs in almost every car they were installed in.I cant say hw many sets I had to pull ecause they ran bad.Cant see how they still make them.Rocky

Thanks y'all

The Rapidfire plugs were developed to cut down on irregular misses by GM engineers who were doing a lot of emission testing and monitoring cylinder-by-cylinder. I believe there are a couple of SAE papers about this. So it is not all smoke and mirrors.

The question of whether you'd notice it on a dyno or racetrack is still up in the air, I'd say probably not. But that isn't measuring as precisely as the tests used to develop the plugs.

If they work in one engine they'll work in others.

I put a new set of highest-end NGK Iridium plugs in my Hyundai and noticed exactly NO mpg increase over the 100K plugs they replaced. When I pulled them out a year later one had the thin wire missing, one had it apparently welded to the ground strap instead of the center electrode, and the other two were OK. Kind of disappointing.

In real life situations, unless the current ignition system is failing or faulty there isn't a whale of a lot of power to be had by any trick ignition.

R.

I run the Denso Iridium plugs with the thin electrode and they work perfect in my engine. I just picked this plug by happenstance at work one day. I had My Indy heads on the bench at work assembling them and I was doing a tune-up on a new Tundra and just screwed a plug in my Indy head they fit perfect and I just put them in for break in. They ran perfect on the initial test drive so I left them in and I'm on my second set in 5 years
Gus

AC plugs suck in Mopars!

Agreed. Also I have found in my experience that 95% of plugs get changed for no good reason (I'm guilty of this as well). Most can just be cleaned and reinstalled.

I believe there is a US Patent Number on the Rapidfire spark plugs package that you can look up and read on Google’s Patent service. Patents usually have a “History of the Invention” section that is well worth reading and points out key past improvements in spark plugs.

Me too.

I don't even put Champion plugs in my lawnmower anymore
If there is a better plug out there then why not use it

Gus

They work...

Most champions I have changed were due to resistance being too high causing a miss, they use crappy resisters....and almost no one checks the resistance of their plugs with a meter. Tim

The internal resistors of Champions not only go bad more often than sparkplugs should, but Champion uses a unique “semiconductor” resistor that is hard to realistically test. I have had to use a 1000 volt megaohmeter, the old style hand crank megger.

If it is a Champion Double Platinum type, the little tiny discs crack their welds and disappear.

Sample quote

SAC-9 Suppressor
Champion developed the SAC-9 suppressor in the early 1980’s. This extremely reliable resistor/suppressor is formed from strontium carbonate, aluminum oxide and copper oxide powders. In fact, out of billions made, not a single SAC-9 suppressor has ever been found to fail in service. They are used in many Champion “R” type resistor plugs. An important feature of Champion plugs with the SAC-9 suppressor is that the resistance of the plug cannot be accurately measured with typical low voltage ohmmeters.

From

http://www.motospecs.com.au/assets/files/downloads/The_Champion_Difference.pdf

http://www.championpowersports.eu/assets/Uploads/II-Partnumbering-structure.pdf

Some of these newer style, long mileage plugs are designed to work with newer style ignitions, in that the juice needed to get a good spark might not be enough from a stock ecu or points. I'd consider the recommendations of whatever the manufacturer of your ignition system recommends when picking a plug.