What kind of plugs should I use on my 1967 Fury III

What new style spark plugs fit a 1967 Plymouth fury III with a 318 f code engine, automatic transmission, with 2 barrel stromberg carburetor #WW3-273 without clean air package and with champion N-14Y three eights inch reach spark plugs? Does the plymouth use the 3/8" plugs short reach as the shop manual says? What new style plugs are recommended to replace the old N-14Y Champion plugs? Do I need to use the 3/8" reach plugs? Should I use a platinum plug such as autolite?

If you have the shop manual, stick to what it calls for.

They still make N-14-Y…Why change?

You got two great replies so far. Other than trying to get longer spark plug life with platinum, what results are you hoping to achieve by using a different plug?

I’d stick with the factory plugs. I did tuneups on hundreds of Chrysler/Dodge/Plymouth cars of that era. The factory plugs work fine.

The shop manual says the N-14Y is a 3/8" reach and the plugs are no longer available. I wanted to use a platinum plug. I am not sure about the reach issue. The N-14Y Champion plug is listed as being a 3/4" reach. Is the short reach plug correct and if so what plug can I buy that has the short reach since N-14Y is no longer available and a long reach plug. Is the shop manual a misprint? I am confused. Please help.

I didn’t realize the N-14Y plugs were no longer available.

Whatever plug you replace it with, you need to make sure you preserve the reach and the heat range of the N-14Y. You’re asking for trouble if you vary those two.

It looks like you’re getting conflicting information about whether the N-14Y has a 3/8th or 3/4" reach. I thought it was 3/4, but that’s only from memory. You need be sure and get the reach right.

Hopefully you’ll find available replacements in the plugmaker’s cross reference charts.

See the decoding of Champion numbers at

The N-14Y is definitely a 14mm thread, 3/4" reach plug.

sparkplugs.com lists an Autolite #85 for your car, in stock, but I can’t vouch for their accuracy. BUT the Autolite cross reference manual says an Autolite #66 is the correct model. http://www.autolite.com/pdf/auto_crossref_0311.pdf

Thanks for your replies. The shop manual says the N-14Y is 3/8" reach. Does anyone have the 1967 Plymouth shop manual that can confirm this fact under the electrical section specifications? Is the manual incorrect and is the reach of 3/8 incorrect and a misprint. I want to use a platinum plug since it lasts longer. Can anyone suggest a best plug brand and # and verify the reach for me. Perhaps Autolite platinum is not the best way to go. Champion N-14Y is no longer available except on Ebay and I want to put in a longer lasting plug. I can’t narrow down the exact plug # to use for a autolite platinum plug. I might try some other brand if anyone has some suggestions. Thanks,

In 1967, two different plugs were used. J-14Y is a 3/8" reach plug. N-14Y is a 3/4" reach plug. So pull one of your plugs and see if it’s long or short…Chrysler specified resistor plugs, RJ-14Y or RN-14Y, depending on reach…Using the Autolite equivalent is no problem…

I like to use the OEM style plugs, whenever possible, in any of my vintage rides. I have no problems buying them from the local auto parts store. If you are having problems getting yours, you could log onto Autozone’s web site, enter the year, make, model, engine for your car and find what they list as substitutes. Here’s what I came up with;

3/8" reach = NGK Ix Iridium 7355
Autolite platinum AP86
Bosch platinum plus 4036
Autolite resistor 86

3/4" reach = Autolite double platinum APP66
Autolite single platinum AP66
Bosch platinum plus 4018
Champion 3405
Autolite resistor 66

The list actually goes on, you need to log on and double check for yourself.

The Ix Iridium’s are going to be beaucoup bucks. Unless your engine is running uber clean, you may not want to opt for any big dollar plugs as they may be fouled out long before they wear out. This is one of the reasons I choose OEM spec’d plugs because the long life ones are a waste of money in that situation.

Auto Zone, O’Reilly, and other parts stores will show a complete list of all the brands and types that are right for your car. If there are platinum, copper, or irridium they will show up on their list. For a car that age your choices will most likely be fewer but they’ll all be right for that application.

Thanks folks: I still can’t figure out why the official mopar shop manual says N-14Y Champion plugs are 3/8" reach. I think those plugs are no longer available. Does anyone know if this is a misprint or should I use 3/8" or 3/4" reach plugs. Does anyone else with the same 5.2litre V-8 318 ci engine code f with 2 barrel stromberg carb know what is up with the data in the original shop manual in the electical specifications pages? Does anyone with a 1967 Plymouth Fury III and the same engine know what plugs to use. The spark plug web sites show both 3/8" and 3/4" reach as options. Does anyone know for sure? I think I have used both long and short reach in the engine without realizing it. Which is better or which is correct? I want to get the best plug for my engine in a long lasting plug with the correct reach for the best perfomance. Thanks for replies to solve the mystery.

The reach length should equal the length of the threads in the head, leaving only the electrode exposed in the cylinder.

One thing you can do is to measure the length of the plug threads. Get a piece of stiff wire (coat hanger), bend the tip 90 degrees. Slip it into the plug hole and get the 90 degree tip caught on the inside of the threads. Mark the outside of the wire where it enters the plug hole. Then remove the wire and measure the distance between your mark and the end of the wire. It should either be 3/8" or 3/4".

Be sure to use a long piece of wire - as having that long “handle” minimizes the risk of it falling into the cylinder.

thanks for your advice. so if i stick the coat hanger wire with the 90 degree bend into the plug hole and hold it against the side of the threads and pull the wire up until it stops because of the bend catching on the bottom of the head and then measure the distance that the bend of the 90 degree angle and the top of the wire that extends out of the threaded hole makes would be 3/8" or 3/4" and that would tell me the reach that I need to use. Is that correct? Thanks for your reply. Russell

I would use a bright light and a hand mirror and LOOK at the spark plug holes. The difference between 3/8 and 3/4 is obvious. WHAT TYPE OF PLUG IS IN IT NOW ???

I wanted to get it right and use the specifications from the shop manual. I have put both long and short reach plugs in it. I noticed this and was confused as to what was the correct plug since the shop manual appears to have an error in the listing.

Chrysler had three V8’s available that year, the new A block 273-318-340, the B block 383-440 and the 426 Hemi. I don’t remember if the Fury III could be had with the Hemi, it was available in the Belvedere and GTX. I had a B block engine in a 66 Dodge and as I recall, it had the short tipped plugs. Maybe the different engines are the source of the confusion.

Desotododgeplymo wrote:

so if i stick the coat hanger wire with the 90 degree bend into the plug hole and hold it against the side of the threads and pull the wire up until it stops because of the bend catching on the bottom of the head and then measure the distance that the bend of the 90 degree angle and the top of the wire that extends out of the threaded hole makes would be 3/8" or 3/4" and that would tell me the reach that I need to use. Is that correct?

That is exactly the procedure I was thinking of.

The 318 got a make-over in '67 and different heads were used. Some took the N-14Y plugs and some took the J-14Y…

318 V8

“The LA 318 was a 318 cu in (5.2 L) relative of the A 318. Like the A 318, it has a larger bore at 3.91 in (99 mm) as well as a stroke of 3.31 in (84 mm). It appeared shortly after the 273, in 1967, and proved tremendously successful. A version of this engine was available until 1991 when its was superseded by the Magnum version (See below). It used hydraulic lifters and a two barrel carburetor for most of its production, though four-barrel Carter Thermo-Quad and Rochester Quadrajet carburetors were used in police applications starting in 1978. The 318 received roller lifters and a fast-burn cylinder head in 1985, and throttle-body electronic fuel injection for truck applications starting in 1988.”

The “A” 318 was the old, heavy, model. The new lightwiight “LA” 318 burst on the scene in 1967. One used the short plugs and the other used the 3/4 reach plugs…