Another 440 Mag Spark Plug Question

[Havasu Dave]

Hi folks,

Looking through the forum, I saw some recommendations for Champions and ended up getting a set of RC12YC plugs.

Now that I am in the (extremely fun) process of removing the old ones, I discover they're Autolite 85 plugs.

I cant help but to notice that the Autolite 85 thread length is about half of what the Champion RC12YC threads are.

Stock heads. Am I okay using these plugs? Thanks in advance.

 

[lewtot184]

the rc12yc is a 3/4" reach plug and won't work with stock iron heads that need a 3/8" reach plugs. if you want champion plugs they will need to be "j" series not "c" series; such as j10y, j11y, rj12yc. autolite 85's are good plugs too. the "j" series champions are becoming hard to find.

 

[Havasu Dave]

Thanks Lew, it makes sense. When I researched this this morning, I must have been reading threads about aftermarket heads.

 

[lewtot184]

the 3/4" reach plugs are for alum aftermarket big block and all small blocks.

 

[RJRENTON]

Lewtot is correct. The stock 440 heads use a 3/8" reach plug. It is the owners choice to use a projected nose plug or a conventional gapped plug. Plugs from various manufacturers will work well. Autolite AP85 plugs are platinum tipped, projected nose and are usually available for $2.00 (+/-). AC# R43S also work well. Champion RJ-12YC work well. I use Champion UJ-11G or HO-8A, which are NON projected nose plugs.
Cheers,
RJ Renton

 

[Havasu Dave]

Thanks guys. I'm one of those 50-somethings who finally got one of these cars. (67 Coronet RT) I feel like a real jackass asking such a basic question, but I am glad I did.

I pulled out a couple of the Autolites and found a good burn. I'll back pedal here and get a proper plug socket, and pull each plug and check for a .040 gap- as it's got a hotter ignition. (More stuff I learned on this form) Thanks all for the helping hand.

 

[Havasu Dave]

Someone should write a Country Western song about changing 440 plugs. Or maybe I am just not limber enough.

All 8 plugs showed good combustion, but the gaps were anywhere from .021 to .032. I gapped them all at .040. (hot coil) All but #1 and #2 I had to get from underneath.

- - - Updated - - -

Someone should write a Country Western song about changing 440 plugs. Or maybe I am just not limber enough.

All 8 plugs showed good combustion, but the gaps were anywhere from .021 to .032. I gapped them all at .040. (hot coil) All but #1 and #2 I had to get from underneath.

 

[Dennis H]

N G K's.

 

[TxDon]

Someone should write a Country Western song about changing 440 plugs. Or maybe I am just not limber enough.

All 8 plugs showed good combustion, but the gaps were anywhere from .021 to .032. I gapped them all at .040. (hot coil) All but #1 and #2 I had to get from underneath. QUOTE]

38 years ago I could do them all from the top but I remember almost climbing in with the motor. I also must have used some tools I no longer own because I can't do it now. I was able to do the driver side from above but had to get under for the passenger side.

 

[Havasu Dave]

It's embarrassing, but at about the time I figured out I needed to jack up and support the car for the passenger side bank, I also realized I needed to take a couple of night time Aleve pain pills.

Long-term disability, career USMC, blah, blah, it was disheartening to realize that something so simple as changing plugs was just about pegging my ability.

The last plug I did, (#7) I ripped the MSD wire out of the socket, so had to repair that. The plug wires themselves look ugly as hell, since this is an AC car with PS, there just doesn't seem to be a clean way to run the left bank wires and not burn them on the manifold, or have them rub on the steering shaft. (Thankful that dual snorkel filter covers up almost everything)

Wish I could fake my MOPAR-ability a bit better. I feel more like a custodian, than an owner. Not moving mountains, just trying to keep her solid and running. (and wishing a red-cap MOPAR battery repop didn't cost $300.) :icon_surprised:

 

[lewtot184]

if your using stock cast exhaust manifolds run the wires the way the factory did. use 90 degree boots on the plugs and straights at the distributor. you can buy repopped wire brackets for a nice clean installation.

 

[Havasu Dave]

if your using stock cast exhaust manifolds run the wires the way the factory did. use 90 degree boots on the plugs and straights at the distributor. you can buy repopped wire brackets for a nice clean installation.

Lew, thanks again. How were they ran from the factory? I have been unable to locate any photographs showing how the left bank was run. I do have the original manifolds, and chrome valve covers. There are two single-wire brackets atop the valve covers for I assume, the #7.

I can not understand how the remaining wires were routed past the air conditioning compressor mounts, and through the power steering hoses. Plenty of non-AC photos out there. I am running angle plug boots, but will be using new wires- since these are too long no matter how I route them.

Any photos?