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Author Topic: Spark Plugs  (Read 1188 times)

Bob Schaefer

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Spark Plugs
« on: June 18, 2010, 09:04:49 AM »

I read a thread over on CBody Dry Dock, which discussed spark plug choices for our Big Blocks. This thread was specific to a 440, but seemed to apply well to a 383, too...
 
The question I have relates primarily to the reach of the threads... I see that the stock replacement is a Champion RJ12YC, which has a 3/8" reach, but there was also a mention of the RN12YC, which looks like it has a 3/4" reach.
 
So, the questions are... Is there an advantach to the longer reach?
 
I presume, since the illustrious leader of this forum is the one that mentioned the RN12YC, that there is not a problem with having longer thread reach.
 
I will be picking up the RN12YC today, but I just wondered what went into the decission making process. Just trying to learn as much as I can.
 
Thanks,
 
Bob
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Steve

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« Reply #1 on: June 18, 2010, 10:08:23 AM »

Hey Bob  RN's are for the LA.  RJ's are for the BB.  The real difference is the thread length.
I wouldn't put that long thread in there.  I think they may be the wrong thread size too.
 
This is the problem when you have multiple cars, with different engine sizes, and being old. 
 
Mannnn   That was an old thread. . . .
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Bob Schaefer

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« Reply #2 on: June 18, 2010, 03:28:11 PM »

Well, I was trying to utilize the search feature before posting a question... but I ended up getting the RJ12YC's afterall...
 
Thanks,
 
Bob
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Steve

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« Reply #3 on: June 18, 2010, 06:44:58 PM »

Good Move.  I don't think the RN's would have worked anyway.
 
You could use a hotter heat range, but that is only when you have a specific problems.
 
The best running plugs (Here we go, debate time) for the Mopar is the Champion.  The closest winner, and 2nd place is the NGK.
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Leaburn Patey

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« Reply #4 on: June 18, 2010, 07:38:17 PM »

J14Y for the 383.Part #2444870...NOS plugs..
 
CBarge2010-06-19 00:41:27
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Stan Paralikis

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« Reply #5 on: June 19, 2010, 03:05:01 AM »

Show off!!!

300rag

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« Reply #6 on: June 19, 2010, 04:58:19 AM »

Quote from: CBarge
J14Y for the 383.Part #2444870...NOS plugs..
 
 
If the motor has only 8 spark plug holes, why do they come in boxes of 10???????
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Stan Paralikis

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« Reply #7 on: June 19, 2010, 06:24:54 AM »

It's the same with hot dogs and rolls.....

Leaburn Patey

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« Reply #8 on: June 19, 2010, 10:01:38 AM »

Quote from: 300Rag
When you have HP logs,one spare for #7 if you break one,and spare for #6 cylinder that fouls up!! LOL!
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300rag

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« Reply #9 on: June 19, 2010, 02:40:35 PM »

Quote from: CBarge
When you have HP logs,one spare for #7 if you break one,and spare for #6 cylinder that fouls up!! LOL!
 
See Stan, at least there's a legitimate reason, unlike the hot dogs 
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q-ship

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« Reply #10 on: June 20, 2010, 10:50:28 AM »

CBarge: I believe you will find those J-14Y plugs to be far to hot for todays fuels.
 
By the early 70's the J-11Y was the recommended plug, and in fact Champion combined them both and only produced the J-12Y as the only (Champion) BB Mopar plug in the mid 70's.
 
The problem for the last several decades was that all the plug manufacturers simply re-wrote the plug charts to reflect what they produced, not what works best. This is a problem for all makes of older, non Chevy engines (they still produce all the plug choices for the Chevy's last time I looked).
 
I was lucky enough to know a parts guy at a Plymouth dealer when Mopar was blowing out all the Mopar branded J-11Y and RJ-11Y plugs, and bought all they had for $1.00 per set, so I'm set for life.
 
The J-12Y's will work fine, but will need a slightly richer mixture to keep pinging down, as J-10Y's (colder) were the plug of choice after adding headers or other efficiency increasing mods. 
 
The other problem is that no matter what the designation number of a plug, it doesn't necessarily have any correlation to the same plug number today, as the numerous heat range numbers are combined to whatever the best selling plug number is.
 
Experimentation with other brands is about the only way of learning what the real heat ranges are, as there is no way to realistically cross reference them anymore.
 
It's to bad that some one doesn't make a true J-11Y or equivalent nowadays as I have yet to see any that work as well for an Iron headed, or even some aluminum headed combos.
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Stan Paralikis

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« Reply #11 on: June 20, 2010, 11:21:24 AM »

I found out, too late, after I built 440-WOB Part 1, that my motorhome heads were the ONLY BB heads that required a different style plug  from all the rest.  In 440-WAO Part 2, I had the correct taperd seat plugs.  Unfortunately, it's getting harder and harder to find this plug and I'm wondering if I should stock up now?

Snotty

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« Reply #12 on: June 20, 2010, 05:51:14 PM »

Quote from: Commando1
It's the same with hot dogs and rolls.....
 







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Steve

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« Reply #13 on: June 20, 2010, 05:59:14 PM »

Good Info Q Ship
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Leaburn Patey

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« Reply #14 on: June 21, 2010, 01:53:38 AM »

I bought the plugs for display during my NOS influenced intoxication.
I use NGK'a in my 318 and honestly,I have been using Delco plugs in my 440 for years simply because of the heat ranges available.
 
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