AC Rapid fire spark plugs.....

Manipulator

Senior Chief Petty Officer
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Apr 11, 2005
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I was told that AC Rapid Fire #10 can be used in my boat as it replaces AC-MR43T. I checked and it does. Any luck with these plugs? Am I wasting my money to buy a set? Says increased fuel economy, better starts and performance. Hmmmm....
 

KaGee

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Aug 14, 2004
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Re: AC Rapid fire spark plugs.....

Wasting your $$... stick with the MR's.
 

Manipulator

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743
Re: AC Rapid fire spark plugs.....

Really? Why do you say that? I read that GM was switching them to OEM on their vehicles. I know a lot of plugs make all these claims and if they were as good as they say, then the car companies would be putting them in all their vehicles. Well, they say these will be standard equipment on GM vehicles so I thought there may be something with these plugs.
 

kozman01

Petty Officer 1st Class
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Jul 28, 2003
Messages
242
Re: AC Rapid fire spark plugs.....

A few months ago, I found a ton of AC Delco Rapid Fire plugs on clearence at my local Wal-Mart. I think each 2-pack was going for 3-4 bucks. Bought 8 for my 96' Yukon and for the last 10-15K miles, they seem to have worked fine, just FYI.
 

Buttanic

Senior Chief Petty Officer
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Sep 25, 2003
Messages
711
Re: AC Rapid fire spark plugs.....

Ther are some slight advantages to using a small wire center electrode plug. It may improve starting and is somewhat more resistant to fouling. Plug life might be a little longer but considering regular plugs will go 100,000 miles in a car it's really not a issue in a boat engine.Will you be able to see or feel it in the performance of your engine, a big no.
 

mkast

Lieutenant Commander
Joined
Nov 6, 2002
Messages
1,934
Re: AC Rapid fire spark plugs.....

Take a look at the Rapid Fire plug, it has an extended tip. Autolite and Motorcraft plugs have been running an extended tip for...thirty years.<br />You will never notice the difference in your boat between the A/C plugs and the Rapid Fire plugs.<br />At least once a month this same question is asked.<br />It ranks up there with the, "I only run 93 octane fuel in my 9 to 1 compression engine".
 

Manipulator

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Apr 11, 2005
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743
Re: AC Rapid fire spark plugs.....

Thanks for the advice. The reason I was considering it was there is a guy on Ebay selling them new for $1.98 a piece. The MR43T are typically $2.59-$2.99 each.
 

jch7450

Petty Officer 1st Class
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Apr 13, 2003
Messages
230
Re: AC Rapid fire spark plugs.....

stick with the old ones
 

JasonB

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Feb 10, 2003
Messages
1,455
Re: AC Rapid fire spark plugs.....

I just searched high/low all around me for some MR-43TS plugs and they are like finding hens teeth. Since I am freshwater only and generally replace plugs every couple years, I ended up with some CR-43TS. They are supposed to be the same plug without the stainless. $15 for a box of 8.
 

Bondo

Moderator
Staff member
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Apr 17, 2002
Messages
71,112
Re: AC Rapid fire spark plugs.....

My NAPA Guys tell Me the AC-MR43TS is Out of Production........<br /><br />I'll be Reloading with AC-MR43T plugs again........
 

Manipulator

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743
Re: AC Rapid fire spark plugs.....

MR43TS<br /><br />R=Resistor<br />4=14 mm threads<br />3 or 4 is the heatrange<br />T=Tapered Seat<br />S=Stainless<br />M=Marine<br /><br />Since I am in fresh water I really do not see the need for stainless. <br /><br />R43T I hear is the exact plug for automobiles. Same plug just not stainless and will work fine. <br /><br />Champions are RV8C but my local marina says the new plug is RV15YC.<br /><br />NGK BR6FS will work<br /><br />Autolite 144 will work
 

JasonB

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Messages
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Re: AC Rapid fire spark plugs.....

I Tried the Autolite 144 in mine and it fouled much faster than the MR43TS for some reason. The 43TS is definetly a bit longer.
 

ron7000

Banned
Joined
Jul 10, 2004
Messages
498
Re: AC Rapid fire spark plugs.....

when switching from one plug brand to another, you are not always at the same heat range. If going to an autolite 144 seemed to foul faster than the AC 43 then that seems to suggest that it's a colder plug, or you have an air-fuel mixture problem and which may be getting worse. The first step would be to go one then two heat ranges hotter on the autolites.<br /><br />Marketers would have you believe there's some high tech science between spark plugs, when there isn't. The only thing new is they're able to manufacture thin-wire center electrodes down to 0.4mm and 0.7mm and they're using iridium. The key point is manufacture cost effectively!<br />I believe they can have advantages over traditional plugs, theoretically, but on a well tuned basic motor which we all run the advantage is not noticable. I've never run rapidfires but from pics they look like a thinner-wire electrode than traditional plugs which means they'll fire easier or it takes less voltage to make a spark.<br />some good reading about spark plug technology at<br /> http://ngkaz.home.att.net/wsb/html/view.cgi-home.html-.html
 

John_S

Rear Admiral
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Jun 21, 2004
Messages
4,269
Re: AC Rapid fire spark plugs.....

FWIW, I was able to get the NGK extended tip, from my dealer, yesterday. BPR6FS, A bit pricy from the dealer, but seen them on the net for about $2 each.
 

Manipulator

Senior Chief Petty Officer
Joined
Apr 11, 2005
Messages
743
Re: AC Rapid fire spark plugs.....

O'Reilly Auto Parts had the MR43T for $1.89ea! The one right down the street even had them in stock. I was thinking about getting the Autolite 144 as it was $1.39 but went with the originals. I have heard Autolites were crap but who knows. They do seem to be the most economical. <br /><br /> http://www.oreillyauto.com/EW3/ProductDetail.do?id=31796615&
 

Gary H NC

Fleet Admiral
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Dec 1, 2005
Messages
8,972
Re: AC Rapid fire spark plugs.....

Stay with the AC plugs.I have run the AC 10 plugs before with no problem at all.Could not tell a bit of difference between the 10's and the MR43's..
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,591
Re: AC Rapid fire spark plugs.....

Rockauto.com has the AC mr43t plugs for $1.51.

I just add them to my order when I am buying filters and other stuff for my autos.
 
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