Spark plugs

[56pan]

Description: What plug should I use and what is the gap?

I have a 1956 Panhead that has been converted to 12 volt, an S&S Super E carb and a small cam. Just a little bit bigger than stock. The guy who rebuilt my engine said to use Autolite 55 plugs. Cross referenced to Champion this is N12YC. Does this sound right? Everything I have read tells me to use J12YC. The difference is that the N plug is 3/4" long and the J plug is 3/8" long. What plug should I use and what is the gap? Also what jets for my Super E? I have 72 main and 295 intermediate in there now. Thanks.
Bill

[fourthgear]

56pan
As long as you have stock type heads the Champion J12YC are what I use, there are a lot of other plug brands that work , there was a thread here about them a while back and I gap them at .28 but every motor is diff. and playing with gap can get better performance to a degree. I have been using Champion plugs for over twenty five years in Harley's.

[chucklbones]

hey now
been runing autolight 4257 for years work great fer me
see ya
chucklbones

[Skip]

Like fourthgear been running Champions J12YC for quite awhile now..started changing them every ride though...they have a 2 year warranty here at Autozone so I replace them every weekend with a new free set...do the same in the wife's sportster with the same J12YC plug...Skip

[caschnd1]

Change them every time you ride!? LOL
I use Autolites and change them once a year whether they need it or not. I ride every day... I'd be late to work if I had to change my plugs every morning.

-Craig

[Skip]

Hey they are free and it takes less than 30 seconds to change them, even if I have to unpack my tool pack, so why not...other wise I would not run Champions..I find they foul/miss fire too much for my taste...I have run them for a season at a time too, but why???...I buy them, for 1.68 each, 12 at a time at gap them all at once...I'm never late...no luck with autolites...Skip

Skip...

[Kuda]

By any chance do you run a mag? I've been told by a real mag expert (which I'm NOT) that the Champions, even the ones marked non-resistor, DO have measurable resistance and should never be used in a mag. He said Autolite is the way to go with mags. Just a thought...

-Kuda
'49 FL

[Skip]

My wife's sportster has a Mag and ran autolites in it...they would go bad it seems just sitting there...I swear I put new ones in on Friday night...got up Saturday morning and the rear plug would not fire...put J12YC out of the Pan in it and it fired up...never used Autolites again...I know you can get bad plugs...It is my understanding you have to run soild core plug wires to get a ggod spark and fire...took me a while to find them but it seemed to help all the way around...

[Sidecar]

I would like to try a set of Denso plugs ( If they make them ) They ain't cheap though. I always had great experiences with them in other bikes. Worst ones I ever tried were splitfires. They were great for about 500 miles in my bagger and then it starting missing and coughing. 2nd set did the same.

[Skip]

spent 14.00 on those fucking screaming eagle plugs...I swear the would not even fire the bike up...pounded them into dust...Skip

[Sidecar]

What the Hell. I just bought Iridium Denso spark plugs to try. I need to stop reading these spark plug topics !!! Smile It'll be a while before I get them installed though. If I notice anything, I'll post it.

[Pantony]

You know years ago I was a wrench on everything from injected alcohol modifieds to USAC midgets to Outlaw sprint cars, and Skip, they all had magnetos and back then they used everyones magnetos. From industrial engines to Joe Hunts and even from aircraft engines and at the track the plug of choice was Autolite. We milled all kinds of plugs in half and found Champions grow algae between the porcellin and the electrode. once we found that out we never used champions again,,,,,on ANYTHING! If you go to the gallery and look in Panheads near the back page My 1948 FL is there, "48 At Home" that picture was taken this May at 500mi. That bike has 2500mi on it now still with the same Autolite Platinums in it. If you keep changing your plugs every time you ride you will surely wear out the threads in the heads and you will be putting inserts or Helicoils in a lot. Just leave them be, they will be fine for a long time. If you don't know what to do with your free plugs give them away to someone that really needs them.

[Cotten]

Algae!?!
That finally explains where I got my herpes.

....Cotten

[mbskeam]

thats a good story......
I'd stick to it............LOL
I got mine off the....... toilet seat....... ya thats it.....the toilet seat..... LOL

mbskeam

[VPH-D]

I have always used H D or Champion plugs, which are the same thing. I know the hot rod types favored Autolite at one time, and maybe still do. A 70 or 72 main jet should be in the ball park, as should a .28 or a .295. Keep your accellerator pump shut off while you are fiddling with the jetting.
VPH-D