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Spark Plug Observation

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Musicman

Musicman

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Today was tune-up day. I replaced the points and condenser. I elected not to replace the rotor and cap and instead cleaned them up really well. I also decided not the change the wires, as the present ones are pretty new. I checked my plugs and they looked really good. There was no evidence of oil, gas, or improper burning.

When I took the car out for a test drive everything was great except for some hesitation while accelerating between 3,000 and 4,500 rpm. I thought it might have been a timing issue, but I figured I'd replace the spark plugs first and see how the car would run then. Well, I replaced the plugs that were in there (Champions) with NGK's. The designation numbers I don't remember right now, but they were the "hotter" plugs of the ones that are recommended for the car. When I took the car out for a spin after putting the new plugs in it ran smooth as silk. No more hesitation all the way up the tach.

I was very happy that a simple change of spark plugs made all the difference in the car's acceleration.
 
Dave, our cars just seem to love NGK's. That's the only thing I run in all of mine. Gotta put a set in the Volvo tomorrow.
Jeff
 
MusicMan, were they NGK IX brand(about 5 or 6 bucks apiece) or were they standard NGK plugs(about 2 or 3 bucks apiece)? The IX kind are a new type that uses a precious metal that is supposely harder and stronger than platium. I thought I read on this forum a year ago or so to stay away from platium. Something about the platium chipping off and going into the cylinder. Anyone else remember something about platium. Thanks
 
Jerry,

I used the NGKBP5ES plugs. They're definitely not the IX brand you speak of.

Thanks for the heads up.
 
Hi David,

I'm also a big fan of NGKs and have used them for 25 years. Sure, I've tried other things, here and there, but nearly always came back to the plain-Jane, standard NGK (not the multi-electrode, platinum, unobtanium or anything else) for use in a wide variety of cars, trucks and motorcycles. I'm not sure the particular one for your TR6, my TR4 uses a different plug I'm fairly certain.

Another thing I've begun doing is using dielectric grease on all the plug wire connections, at the plug and at the distributor. That's particularly helpful with modern, higher voltage ignition systems, but I figure it can't hurt on the old low-tech ignitions. If nothing else, it keeps any moisture out and makes the plug wire boots easier to get off.

Chasing that miss, you might look closely at the inside of the distributor cap and rotor, to see if there has been any tracking or are any cracks. Also check the points. Again, not sure about TR6, but the currently available points for TR4 stock dizzy reportedly wear rapidly, especially when new. (My car has a Mallory dizzy, so I can't really say I've had any personal experience with this.)

Keep us posted what you find.

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Alan,

Thank you for the advice. As you can see from my first post I've already replaced the points and condenser and I inspected the cap and rotor carefully. Instead of replacing the cap and rotor I elected to clean them up instead. The cap is in fine shape. I found no evidence of tracking. Like I mentioned above, I decided to change the plugs only after experiencing some slight hesitation at the higher revs. The new NGK's took care of that problem immediately. I went with the hotter NGK plugs only because I read where a hotter plug is a good way to go with the TR's that are heavy on the emission control systems, which mine, being a 1975 model, definitely falls into that category. The "regular" NGK plugs probably would have taken care of the hesitation problem as well. I figured I'd try the hotter ones first and if that took care of the problem then I'd just stick with them.
 
This won't add to the car knowledge, but the response about the platinum content earlier caught my interest enough to check some data. They probably did have thicker tips ten years ago but at about $910/oz it's probably so thin now that it would blow out on the next exhaust cycle if it did come loose. Come to think of it the newest NGK have a wire like electrode polished flush with the ceramic insulator. Interestingly its resistivity goes way up with increasing temperature, but apparently not enough to hurt its performance. It is the king of the platinum metals though with a melting point of 3200 F. The bit about an improved alloy is probably just creative marketing to save bucks. Because the others: iridium, palladium, rhodium, and few more or their alloys don't quite match up. And they're all cheaper. All I know for sure is that the family beater still has its original NGK platinums and at 155k doesn't miss a bit. Though in the background I can hear someone quietly asking (read nagging)"Have you changed those plugs yet?"
Tom Lains
 
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