Hotter spark plug for my 75 318

[pedal2themetal]

HI. I'm looking for a hotter spark plug with no luck here Not sure if my number is right.. stock calls for an Autolite APP65 I've tried looking for a APP66 and no one has any.. I'm I looking for the wrong plug? if so what should I be looking for?

Thanks Take care be safe
tim

 

[Geoff 2]

Correct factory heat range is 5 in NGK. You would only want a hotter plug for an engine that fouls plugs because of worn rings etc, which is a 4 in NGK.

 

[MoparLeo]

Hotter plugs are usually used as a band-aid for covering up a problem like Geoff 2 said.
What is you reasoning for the hotter plug and why the different brand of plug ?
Factory is an N13Y or RN13Y (resistor) .035 Gap. Timing depends on if it is a California car what type of emissions it has on it. But 0° to 2° was the range. with a stock engine.

 

[pedal2themetal]

HI I just might need to put in new plugs.. Don't remember when I changed them last. Daily driver, 23,000 on rebuild. but I get a purity good miss until the cylinder heats up say 30 sec. or so on a cold start.. I haven't looked at them yet might be a year on them. but was wanting a little cleaner and better burn as well, motor runs at lower than 1/2 way on the temp gauge running a 450 quick fuel and I believe my cam is 4.40 in and ex. stock heads, performer intake. stock exhaust duels straight thru mufflers (not glass packs)

Thanks take care be safe
tim

 

[MoparLeo]

It takes several minutes for an engine to warm up. Modern cars have computers that coverup cold running issues seen on originally carbureted, non computer controlled engine management systems.
Get a true mechanical or digital gauge as the factory gauges are seldom accurate.,
You need to know what the temperature is in degrees not where the needle points to on a sweep gauge.
The engine just might need a good, professional tune.

 

[Cranky]

I used a hotter plug in my old 79 D300 w/360 because it was worn out and got tired of changing the 'correct' heat range plugs so much. Also a Bosch plug lasted longer than all the other regular name brands in one heat range higher. One cylinder was worse than the others so it got a plug that was 2 heat ranges higher.....

 

[pedal2themetal]

HI Professionals are very few and far between for our older rigs. Shops now a days if they can't plug it in to a computer they don't know poop. I've even taken it to a Rod Restoration shop, What a joke that was They couldn't even run a proper exhaust system, its drags a little and they wanted to run it out the side infront of the back wheels (NOT)... I'm about as Professional as its going to get.. I've been at it on and off since 1966. All my cars/trucks/ are Carburetor. My oldest is my 56 Cj5, 64 International with a 545 stroker, 76 olds, 72 pinto (rat project) & 84 Ranger.
So Thanks to all that tried to help out.. I'll get some new plugs for it and go one step hotter just for a cleaner burn, I'll look into the Bosch..

Thanks again ,, take care be safe
tim

 

[Geoff 2]

If this vehicle is used a lot & will accumulate high mileage, I would buy Platinum or Iridium plugs. They last longer & can fire the spark when conventional sparks will misfire. Cost more, but pay for themselves in a high mileage car.

 

[MoparLeo]

And yet here we are looking for a spark plug...Which is also a tuning aid. Misses until it warms up, Unusual ?
I have hired mechanics who said they had 20 + years experience servicing one system or another and had to fire them because they did it for 20 years the wrong way and wouldn't learn. Experience does not always mean correct. Computers, Exhaust gas analyzers are fantastic in the right hands. The tool is only as good as the user. Everything built since the mid eighties has some form of computer. Probably a lot of older guys on these forums have problems using smart phones. Don't blame the tool. Find someone smarter than you. They are out there.

 

[GTX JOHN]

Recommend RN14YC

 

[pedal2themetal]

And yet here we are looking for a spark plug...Which is also a tuning aid. Misses until it warms up, Unusual ?
I have hired mechanics who said they had 20 + years experience servicing one system or another and had to fire them because they did it for 20 years the wrong way and wouldn't learn. Experience does not always mean correct. Computers, Exhaust gas analyzers are fantastic in the right hands. The tool is only as good as the user. Everything built since the mid eighties has some form of computer. Probably a lot of older guys on these forums have problems using smart phones. Don't blame the tool. Find someone smarter than you. They are out there.

HHHMMMM I'm a little put out by some of your comments ..... you sound like a big headed shop owner... you talk about 80's car having some sort of computer?? I don't care mine is a 75 doesn't have one my 84 Ranger doesn't have one ether... Firing someone with 20+ year experience cause they didn't do it your way.. there is more than one way to do something LOL...

I came here looking just for a little hotter plug for a cleaner burn.. Motor only has 23,000 miles on rebuild (timing gear plastic was broken but since I had it apart I just rebuilt it anyway, Motor was very clean inside, barenings showed no ware) , whole car only has 75,000 miles on it (own by an old lady).

Let me tell you of shops..
I was having a crank no start problem. I was having to turn the key way all the way, I also tried just barely turning past start and maybe it would start.. sounds like ignition switch or ballast resistor. I replaced them it worked for a while then it would start doing it again.. replaced the ecu/icu and it worked for awhile again it would start acting up again.. took it to 2 different shops thru 2 years fighting this. they would mess with it changing things I already replaced and again it would work for a little bit and start acting up again. Both shops changed the same things and it would do the same things. they even changed the coil. both shops even replaced the key switch again one even the tumblers now I have to have two separate keys for doors and ignition.. I spent a couple thousand dollars at shops f-ing with this.. So much for shops...... no shop knows **** about our older cars anymore and those that do are dying off..

I finely came here and asked as it had started acting up only 2 weeks after last shop worked on it and on here someone mentioned a ground issue. So I went on you tube and found a video that showed all the damn connections Plymouth had in there ignition system that might cause this problem.. I found a connection on the passenger side fender and unplugged it and the motor died. so it looked a little tarnished so I cleaned it and it hasn't failed to start in months... So much for shops and their fancy tools.. So after thousands of dollars spent at shops it was a F-ing ground/plug issue no one found...

OK I'm done venting..

Thanks again to all the helped, take care, be safe
Tim

 

[RJRENTON]

Recommend RN14YC

This is a good recommendation. If you're willing to try something else, consider AC # R46XLS. This is one step hotter than standard (R45XLS), it is 3/4" reach, 14mm thread, resistor design, 6 heat range (highest AC makes), extended firing tip, standard alloy. Relatively inexpensive. NGK offers several variations and heat ranges, firing tip designs and alloys....reasonably available and costs. Suggest you look at NGK's literature for heat ranges, configuration, features.....very extensive.
BOB RENTON

 

[MoparLeo]

No. I was a store manager and service manager for Bridgestone/Firestone and worked in the industry since 1973.
Sorry you couldn't find a good diagnostic man but you can't put everybody in the same boat. Good and bad in every profession.
Mopar had always had issues with grounds in their electrical systems.
Always the first thing to check. As far as replacing parts that have been replaced already, remember that new doesn't guarantee that it is good.
Finding the problem is the first thing to do. Throwing parts at something and crossing your fingers is the last.
True most of todays, non certified techs are just parts hangers. But not all, you have to find them. They are out there.
Just like shopping for a personal Dr. You have to do your research and not just rely on Internet recommendations.
You don't know who you are dealing with. Might just be a kid in the basement...

 

[pedal2themetal]

HI Got new plugs for it and installed them today.. the old plugs don't look real bad driver side at bottom look a little lean so I fattened up the mixture on that side of the carb 1/8 turn. Passenger side looks a little fat top set so I leaned it up 1/8 turn on that side of the carb. just for shits and giggles.. wires were like new.. popped of easy, weren't stuck to the plug but I could feel the connector clip over the ends when I installed the new ones.

Thanks take care be safe
tim

 

[i_taz]

Anybody have experience with non-resistor plugs...???

 

[RJRENTON]

Anybody have experience with non-resistor plugs...???

YES....I am presently using Champion UJ-11G or Champion HO-8A....both designs are NON RESISTOR, NON PROJECTED CENTER INSULATOR, platinum electrode designs ...3/8" reach in iron heads ..... they work very well and last several years (low milage) running a mix of 100 LL and 93 octane fuel at 25%-75% ratio (approximately). But I only have an AM radio and can hear the sparks in the radio....ignition noise. Now the NGK boys may present a different view point or other opinions..... judt my opinion of course.
BOB RENTON

 

[i_taz]

Are they hotter because of that or a bigger spark...???

 

[RJRENTON]

Are they hotter because of that or a bigger spark...???

FIRST, let me apologize....I thought that your engine was a B/RB block.....your asking about a LA family (318) engine that uses a 3/4" reach spark plug. I had a 67 Belvedere II powered by a LA 318, which I rebuilt using 235 HP/273 parts: cam, rocker arms, push rods, intake manifold and Carter 3854S carb, and a recurved Prestolite dual point distributor for the 273 HP engine. I went from the origional Champion N-14Y plug (non resistor) to Champion N-11Y (also non resistor plug). I've used AC 43XLS or the Autolite equilivant with good results.
The perceived bigger spark, subject to the ignition system's capabilities, just makes it easier to ignite the fuel charge. The heat range of the spark plug is a measure of how the spark plug dissipates the combustion chamber temperature....the longer the insulator the hotter the temperature the center electrode will attain. Beside the length of the insulator, the alloy of the electrodes and configuration of the insulator and its density and thermal conductivity are factors as well. Contrary to popular belief, hotter plugs do not make more HP. The OEM engine designers selected the origional hest range, based on emission control requirements, cylinder head design, and average operating conditions. Since you are contemplating modifications, the plug's heat range must be determined empirically by you...but consider reducing heat ranges by one or two levels depending on the brand you are using.....there is no magic bullet. Just my opinion of course.
BOB RENTON

 

[Dave P]

Keep in mind that "pump gas" these days when "reading" spark plugs is not the same as it used to be. Plugs will look
noticeably leaner.
Also as pointed out a " hotter " plug is just a higher tip temp. Basically have little to no effect on engine operating temps or on the
quality of spark delivered to the mixture. Needs to be warm enough to keep most of the crap burned off but not hot enough to be causing
pre-ignition and self destruction of the electrode. I would argue a hotter plug will have no effect on cold start drivability.
The original post hinted at a lack of understanding of what plug heat ranges could/could not do for you. If I misread the OP, sorry.

 

[Some Car Guy]

Best thing I’ve done to my current car was to toss the champions and put in Ngk. Same problem you had with a miss on warm up. Never seeemed to tune right, plugs looked fine. Now it responds like I expect when I make a change and it runs smooth.

I used to run auto lites until they stopped making them in the US. If you go with iridium, those will actually cover a wider heat range than normal plugs. Like two to three steps rather than just whatever heat range a copper plug is made to be.