Spark plugs

[Geerhead55]

Sorry to scare you guys off asking about MSD spark plugs,,, I know they're fairly new. Perhaps no one has tried them yet? Maybe they'll pay contingency. Just wondering.
Danny Durham

[astikhossw]

I have purchase 3 set of AR-13 plugs this season and each set has been in the engine and iI check my plugs after every race that I have attended and after every race there was a problem with at least one plug mostly the porcelain was cracking.The saving grace of it all was NAPA took back each bad plug and gave me a new one.

[terry1]

I have purchase 3 set of AR-13 plugs this season and each set has been in the engine and iI check my plugs after every race that I have attended and after every race there was a problem with at least one plug mostly the porcelain was cracking.The saving grace of it all was NAPA took back each bad plug and gave me a new one.

That is interesting.I have never had an issue with my AR-13 plugs.

[quickford1]

Most problems are from over tightening the tapered seat plugs'

[jcw31]

to MEXJOE and Alan sorry for going a little sideways but i am not sure there is a good or bad plug.I dont think these companys take the time to sort plugs for different tiers ,too costly. Ive seen on the dyno v59yc,ar3910
Autolite,r5671a-8 ngk all were within 1 hp .When Autolite came out with their ar racing plugs we were using 23s changed to ar 13 driver came in after the heat and said plugs were garbage went back to 23s and was happy. In a small block mopar drag car ran n9yc champ tried 63 autolite car slowed .05 .I saw a 440 mopar on the dyno 414s accels egt was good a/ f was good 1st time out 2runs the plugs were peppered like crazy. I believe plugs from different companys even though crossed to the same the heat range is a little different.
Alan if you need rc12yc pm, me. I think with any plug unless extremely cold or hot, just changes in timing/jetting can make the engine happy.

Have a happy Thanksgiving everyone
Joe

[Alan Roehrich]

I do not know for sure how much testing and sorting they do these days, seeing what gets sent out in a box often leaves me thinking there's not much QC at all any more. They have to do a fair amount though, because the cost of shipping a lot of bad plugs to an OE would be tremendous.

Despite using the hotter RC12YC, my jetting, timing, and even air bleeds are real similar to Jimmy's tune up, and they make close to the same power, being very similar engines.

A hot plug might cause a problem in a circle track application, where it had plenty of time to get really hot. However, in a drag race engine that leaves the starting line at 100 F, and is barely 160 F at the finish line 10 seconds later, you'd need a really hot plug to have a heat range problem.

[Lee Valentine]

What Alan says, I,ve used hotter plugs in my engines for years. Was told to do this by a well respected engine builder.