There is a Dark Side to AC Rapidfire Spark Plugs. It is only a factor if you use after market ignition wires. It is a case of a well meaning innovative feature of each product causing a significant problem when each product’s innovative feature meets and combines with the other products innovative feature.

One of the unique design features of AC Rapidfire spark plugs is a thicker, bulkier ceramic insulator, about 20% wider girth than a standard size insulator. One of the features of some after market ignition wires is a spark plug boot that fits the standard ceramic spark plug insulator snugger than OEM boots fit.

As I found out lastnight, when these two features come together it can become VERY difficult to remove the after market wire boot from the AC Rapidfire spark plug after it has been installed. And I mean VERY. Even if the inside of the wire boot was thoroughly coated with di-electric gel prior to installation. The fit is so tight, maybe part of the problem is the di-electric gel causes an exteme suction lock, especially when considering the smooth ribless design of the Rapidfire insulator (?)

Last weekend I had installed a new set of Taylor Spiro Pro spark plug wires on my AC Rapidfire #14 equipped ’95. After a couple drives I found one of the wire’s to be defective, so I got a return authorization for the wireset and ordered a new set of Moroso Blue Max wires.

Last night I went to remove the Taylors. It was not easy. It was like I had put glue in the boots instead of di-electric. The #8 and #6 ones were almost impossible by hand, partially due to the short squatty trademark design Taylor uses on the boots, to the point that I pulled the wire off the boot on #6, leaving the boot on the plug and the wire end hanging. Had to take a needle nose pliers to pull the wireless boot off #6 after that. Will be interesting to see if Summit still refunds the set now Went and used the pliers on #8 form the beginning and it came off with some effort, but this is totally unacceptable since using a pliers or other clamping force on the boots will likely damage them—Since this set is being sent back I went ahead and made the choice to use the pliers, because my hands alone were not getting the job done. #2 and #4 were equally difficult. Since they are visible I could see the boot hanging on for dear life as I pulled and pulled, even though the terminal had already unsnapped and came loose. Twisting was not help, the boot was stuck fast and would not rotate. My car is stock and no headers for excess heat generation, just has the stock manifold and heat shield.

Okay. So next its time to put the new Moroso Blue Max 8mm’s on the passenger side. I go ahead and install them but being me I realize I need to remove a few to re route them optimally for the looms. Well guess what? Even though I used dielectric again (same tube I’ve used without incident on the stock OEM boots), and even though they had only been on about 30 minutes, it was the same story. Extremely difficult to pull off, the terminal would unsnap loose just find but the boots had a Death Grip on the Rapidfire’s smooth (ribless) fat insulator.

I got them off, but instead of re-routing them I went ahead and removed #8 and #6 also, which weren’t quite as difficult, and then left all four hanging and didn’t reinstall them yet.

I’ve decided that if I installed them on the Rapidfire’s, with the Rapidfire’s extra fat insulator and the wire’s extra snug fitting boots, that then after xx,xxx miles when I go to change plugs I would be faced with the situation of them being truly impossible to ever remove and having to take some insane measure to get them off.

I have decided then, to pony-up for a different set of spark plugs, with standard size ribbed insulators. Even though the performance of the Rapidfire’s is very good, their Achilles heel at least with after market wires, is the extreme difficulty of removing the plug boots from them.

It is with reluctance that I abandon the Rapidfire’s. Now I need to select another plug that performs as well.

To any one running Rapidfire’s with Taylor’s, Moroso’s, or other after market wires that have the snugger-than-OEM fitting boots, I wish you luck next time you go to change plugs or wire.

 

Hmmm...never had that problem with I ran RapidFires on my 92 Mustang GT. I used Accel wires and there was never a problem putting the wires on or taking them off. I wonder if they redesigned the RapidFires, as the ones I used back then were identical to the AC Delco/Champion/Autolite/NGK/etc.

 

I love how this stuff is found out only after the public finds out..
They didnt see this in testing??? What a ball busta...
I would be pizzed as all hell if I had come across this.
Thanks for the FYI..

 

It's easy... too many companies, doing too many different things, without the remotest of chances of doing any thorough testing.

It's sad... But, it's the price we pay for intermingling aftermarket parts. They are engineered around a single paradigm... When that paradigm shifts, we have a problem.

 

What highly sucks is I really like the performance of the Rapidfire's, but that fat insulator making the Taylor and the Moroso boots stick so strongly just kills using them any further for me.

Now to select an alternate plug...

 

Or wires???

RACE ON!!!

 

I was using Rapidfires last year with accel 8.8mm wires, no problems like you described with those. Guess accel is 'normal'. Not like a plug wire is going to make a difference anyways.. good catch though.

 

I like the Moroso's. The Taylors were good too, just got a random bad wire. The culprit is really the fat smooth insulator on the Rapidfire's, so its the Rapidfire's that logically should go...

 

I had the exact same problem with the Rapidfires and Taylor wires. I just about lost my religion trying to get the boots off of #6 and #8. The boots were basically getting sucked back on when I'd let go of them to reposition my hand. The Taylor wires also did this with the NGK plugs I used.

I'm telling you, stock wires and plugs. Can't go wrong, everything works together. You're not gaining anything going to aftermarket unless you've upped your compression.

 

Good catch. I'll need to check on this when I get home since I use Rapid Fires (#5) in my 91.

 

Well, I picked up a set of Autolite APP106 double platinum plugs today. Same design as OEM AC 41-906, they have the platinum pucks but I did research this a little and people have not had problems with the pucks coming off the Autolite (Honeywell) double platinum plugs the way they have with the stock AC plugs. They have a ribbed insulator design that the Moroso wire boots seem to work better with.

I went w/ the OE double plat design because after this I don't want to have to touch the wires or plugs again for another 60,000 miles, minumum.

I don't think its so much the thickness of the Rapidfire's insulator that causes the problem as it is the ribless design. These new plugs are ribbed and close the same thickness of insulator but the boots come off okay (tested boot fit with plug in my hand out of the box)

 

I've been using NGK TR55IX (Iridium plugs) with very good success. I also use MSDs 8.5 mm Super Conductor wires which fit nicely to the opti and the plugs. They've been on for 2 years and it still runs great. I WAS going to try out the Rapid fires, but I think I'll stay with my combo. Thanks for the heads up.

 

Thanks for the one up!

 

Lone Ranger I do feel for you....sorry to hear about your experience...

Mine on the other hand.....well I dunno...can't really explain it....but I am and have been doing exactly what you have said not to do....


Been running the Taylor Wires for about 5 years now and every 30,000 miles I have used the Rapid Fire Plugs...in fact this year...I had to change plugs 3 times every 3 months when I had electrical issues and thought it might have been the plugs. To help you out in your search for plugs let me just say this....and I will probably get bashed by it....for me anyways.....I didn't noticed one bit difference between the $4 RapidFire plug vs the $1 AC Delco standard plug vs Bosch Reg. Platinum Plugs. (I still have the Bosch's in right now)

As far as pulling them off....to help you out there....they make a spark plug puller (special pliers tool) that won't harm the wire and helps get a grip on the wire. For me..Iam gifted...very small arms and wrists but because I workout I can exert some good force where it needs to be on those wires.

Jeff

 

LR, sorry to hear of your problems, but that whole thing is due to no communication among designers/engineers on various product lines....

crap, try header fitment with say steeroids, or some other mod...or for that matter just an alternator change....

I blame computers and CAD/CAM systems...it's just tOOOOO damn easy to change designs wherever, whenever the whimsey comes along.....situation going to get worse over time....

GENE

 

I've been using AC Delco Rapidfire plugs with stock GM plug wires on my 89 for about three years now and I don't have the issue you are describing. I will admit that there is a bit of difficulty removing the wires, but I think that has more to do with the heat cycling that the boot experiences. But with that said, I've NEVER ruined a plug wire like you describe.

Why would GM make a spark plug with a thicker insulator?!? Where the "thinner" insulators not as good?

Have you given any thought to the possibility that a few of the plugs you have where made with insulators that where just on the outer tolerance limit dimensionally? Still passable, but a little bigger than they should be. Have you compared them to a stock set of plugs?

Sorry to hear about the problem though.

 

These are not GM wires, they're Taylor Vertex and Moroso. Both are after market brands. The stock GM wires I took off did not have the sticky boot problem. I removed the stock wires because I don't like carbon core resistor wires and that's what the factory installed type wires are.

You have to see the Rapidfire plug design to see what I'm talking about. They used a fatter ceramic insulator and they made it smooth with no ribs.

 

Thanks for the info.

 

That is crazy! I have the same plugs and Taylor Spiro Pro wires on my 92 LT1 and I have never had an issue getting the wires on or off. I do pull the plugs regularly to read them and see if I need to tune on something. Not once have I had an issue like that and I even have headers. I have had stock wires on other vehicles do what you are describing and also had experience with stuborn wires on some past hotrods but I haven't figured out what makes one wire more difficult to remove than the next... just seems to be random
I wouldn't go flame throwing stuff just because it gave you a hard time.

 

This post was a heads-up, not a flame throwing contest. I don't know where you got that one.

And the later design Rapidfire's are the ones with the fatter insulators, maybe you have the earlier design.

If it happens again, maybe I'll let you take a shot at it since I'm so incompetent