[ponyakr]

" An extended tip plug will probably run slightly cleaner in an old carbureted engine. Slightly more of the spark kernel will be exposed to the mixture giving you a cleaner insulator, especially in prolonged idle, staging situations. No reason not to use them..."

That makes sense. The only possible problem that I've seen mentioned is that longer ground strap will expose more hot metal, which could possibly help promote detonation. Just something I read online. Don't know if there's anything to it or not.

But, if there is no downside to using the projected tips, and they'll run cleaner, sounds like the best choice.

The non-resister plug I'm considering is the NGK R5674. So, what heat range would you guys buy ?

Here's a #6 heat range.

https://www.summitracing.com/parts/ngk-4449/

Here's a #7 heat range, which is one step cooler.

https://www.summitracing.com/parts/ngk-5034/.

How does the NGK #6 & #7 heat ranges compare to AC 45TS, 44TS, & 43TS ?

Would I actually be able to tell any difference between the NGK #6 & #7 heat ranges ? Would the hotter #6 tend to foul less ?

[ponyakr]

Originally Posted by johnta1

NGK cross-referenced plug for the 6X head:


UR4

Yeah, I looked at those. But, they are resistor plugs, and they are a #4 heat range, which on the NGK scale is hot.

https://www.summitracing.com/parts/ngk-6630/

https://www.ngkntk.in/ngk-technology...of-heat-range/

Just assuming that a #6 heat range might be better, for a bracket racer, than a #4 ?

The R5674 plugs are available in a 6, 7, 8, 9, or 10 heat range.

https://www.summitracing.com/search/...rd=ngk%20r5674

[ponyakr]

https://www.hotrod.com/articles/spark-plugs-tips/

[Dragncar]

Originally Posted by mgarblik

An extended tip plug will probably run slightly cleaner in an old carbureted engine. Slightly more of the spark kernel will be exposed to the mixture giving you a cleaner insulator, especially in prolonged idle, staging situations. No reason not to use them. Everyone has their favorite brand, and anecdotal reasons why one brand is junk and another is God's answer to spark ignition. The Champion plug that "came apart" in your engine is the same Champion Spark Plug Company that has made ALL the ACCEL spark plugs since the 1960's. So anyone can have some defects. There is allot of love for AC branded plugs on this board, and I can understand that since they are OE GM. They have a high defect rate of the center insulator being crooked in the shell. I find about 10% of them having the insulator and center electrode so crooked, you have to bend the ground electrode over a significant amount to line them up. The NGK spec'd above is a pretty hot plug. Is there a problem with the Autolite 26's in the engine. How do they look?

I hate to disagree with you, I really do. But Accel plugs are made in Japan and have the same "U" groove that Denso plugs have. My understanding is Accel plugs are Denso plugs, not in any way Champion.
I am a racer that has had Champion garbage come apart on me, twice. The first time nothing fell apart, just all loose but plug still intact. Second time the plug wire was laying across the headers with "half" the large wire. The rest was gone, ate by my 455. I thought a finally blew my engine up. As far as I know nothing was damaged. This was years ago and the engine has not been apart since. Guy at the track said" that is why we have high lift cams". Got lucky. When the engine comes apart I will know the extent of any damage. But the old engine ran its best ETs many times after that incident.
Champions are garbage and should not be in any engine you care about.

ponyakr, just bite the bullet and by some Accel 138s and be done with it. Even my wife said the engine sounded so much better after I pulled the Champajunks for the Accells. And I have had that same set in the engine for many years, still perfect.
If not Acell plugs I would run NGK.

I just found the first plug that came apart but did not fall in engine. The 2 pics are of the same plug. I pulled the electrode back for the 2nd pic. JUNK!! STAY AWAY.

[johnta1]

I never ran NGK's in any of my race engines, so no knowledge about heat range for them. The cross-overs for them show their heat ranges are like 1 size fits all it seems? AC has like 4 or 5 and the NGK's have one for same part number.

The non-resistor plug not sure why one would need them?
With all the electronics around now, it would cause screwy things to the circuits.

I used Accel when I couldn't get the AC plugs. I also will never use Champions again, screwed up too many engines of ours.
(let alone others I know about)

[Elarson]

Boss Bird runs exclusively Champion plugs (C57HX), with zero trouble.
.030" extended tip, cut-back ground strap.

FWIW:
Eric

[Mike Davis]

Spark plugs are cheap. I say run a few different brands and see what your engine likes. Then you will know.
I'd start with a NGK in the -7 heat range.

[ponyakr]

"...The non-resistor plug not sure why one would need them?
With all the electronics around now, it would cause screwy things to the circuits..."

Don't have a radio or anything else that I know of that the plugs could affect. Just a self-contained big cap HEI.

My thinking is why would I want something in the plugs to "resist" the current flow, in a "strip only" car that don't have any electronic gizmos the non-resistors could harm ?

When switching from points to HEI, you have to remove or bypass the resistor wire, to get full voltage to the coil. So, why use resistor plugs ?

[ponyakr]

Originally Posted by Mike Davis

Spark plugs are cheap. I say run a few different brands and see what your engine likes. Then you will know.
I'd start with a NGK in the -7 heat range.

Yeah, $20 a set is cheap, to most here. But I'm retired & on SS & Medicare. MUST do this project REAL cheap, or not at all.

Because of that, I'd like to get as close as I can, on the first try.

Since, according to info posted here, the UR4 plugs are what are the called for replacements when running 6X heads, and they are #4 heat range, I think I'll go down 2 heat ranges from that, & go with the R5674-6 plugs. Some say the hotter plugs are less likely to foul, with a lot of idle time. So, I assume that a #6 heat range MIGHT be at least SLIGHTLY less prone to fouling than a #7.

Does this all sound reasonable ?

This site shows the R-5674-6 plugs to be similar to AC 42TS & 43TS. So, that should make 'em a little colder than what came in mid '70s Pontiacs.

https://www.rrproducts.com/NGK-Spark...6-product52428

Best price I can find is $19.33 shipped. Anybody know of a better price ?

https://www.ebay.com/itm/8-pc-8-x-NG...rd!71251!US!-1

[ponyakr]

Nobody probably cares. But, I'll post this anyhow.

My NGK R5674-6 plugs came in. I was glad to see that they are shorter than the #26 Autolite, because the #7 plug is real close to the steering shaft. I really need either a 90° boot, or at least a 135° boot. But, with the shorter plugs I may be able to use the straight boot on my Taylor wires.

In the 1st pic, the plug on the left is a #26 that was in the engine when I got it, several years back. The middle plug is a #26 I bought a few months ago. Didn't really NEED plugs. But, after getting a new cam & intake, I decided to go with new plugs. Well, I had a few problems, but finally got it running fairly decent. Then it begin to run a little ruff. I'd had trouble with carbon tracking on quite a few HEI rotors. So, I checked my rotor. Sure enuff, it had some tracking. So, I replaced it.

Didn't help. Engine even developed an occasional pop. I checked the wires with a timing light. Several would miss a beat occasionally. I'd heard that the MSD rev limiter modules were prone to problems. But rather than change the module, I bought a rebuilt HEI, & a Pertronix rev limiter module. No change.

Well, I've had problems caused by bad caps. So, I swapped out the cap. No change. I've also had wires go bad. So, I swapped in the new set of Taylor wires I had. No change.

Well, I figured the only things I hadn't changed were the coil & the plugs. So, I pulled a couple of plugs. They were pretty sooty, as expected. But some were wet with gas. The only plugs I had were the old #26 Autolites, I'd kept. I thought at least they weren't wet. So, I cleaned 'em up & stuck 'em back in. That fixed it ! Ran great. No miss at all. Next time, I'll check the plugs first.

Anyhow, I have the new NGK's now. The last pic is a close-up of the tip. I noticed that the ground electrode does not extend all the way across the center electrode. I just looked it up. It's called the "cut-back" style. I've read that some racers cut off some, so more of the spark will be open towards the combustion. Maybe that's why NGK made it a little shorter.

https://www.ngk.com/learning-center/...ctrode-designs

[Sirrotica]

Two words, Fire Injectors, "Run your car without sparkplugs"!!!

[ponyakr]

Yeah, you'd think the guys at the big spark plug companies, like NGK, would know better than to do such a ridiculous thing as to make the ground electrode a little shorter. Don't they know those plugs won't work ?

[Steve C.]

One internet source....

Electricity follows the path of least resistance. It has nothing to do with a split tip or a fancy U groove! The sparkplug does one thing only. It acts as the grounding source for the ignition's electricity and that's it, period, end of story. The only difference with a sparkplug is that there is a gap in the current path which makes the spark. The size of the spark is dictated by the voltage and amperage output of your coil, and the output of your coil is dictated by the saturation (dwell) time of your ignition system.


.

[ponyakr]

"...the sparkplug does one thing only. It acts as the grounding source for the ignition's electricity and that's it, period, end of story..."

So, you're saying that as long as a plug will fit the hole, seal it off, & fire every time it's supposed to, one plug is just as good as any other ? Ground electrode shape/type, heat range, reach, nor any other specs mean absolutely nothing ? If not, exactly what is the point of what you are saying ?

Are you just trying to say that you think the NGK plugs I bought are junk & shouldn't be used ? Are you trying to say I should just go to Wal Mart & buy the cheapest plugs that will fit & seal ?

Whatever.

[Steve C.]

Just a another tid bit off the internet for conversation around the coffee table. Not directed at you personally.

When my car was raced for the most part we used only NGK plugs.

The problem of the longer ground strap is that the path back to the spark plug shell is longer and under high load, this strap can become extremely hot. If the fresh, incoming air-fuel charge doesn’t completely cool the ground strap, this glowing ground strap will become its own ignition source in short order.


.