[ponyakr]

Gonna buy some new plugs for my Super Low Budget 455 bracket engine. Has 6x-8 heads.

After I had a Champion plug come apart at a race, I always used Accel plugs, in all our race cars. Never had another plug problem. But, Accel plugs are now above my budget. And besides that, I don't know if they are still good quality or not.

It has Autolite #26 plugs in it now.

Have been reading a lot of online plug info. Seems that I don't need resistor plugs, since I won't have a radio or any electronic gizmos that would be affected by non-resistor plugs.

Lots of guys like NGK plugs. And, the non-resistor plugs I'm considering are only a couple of bucks each.

I'm considering the R5673 or R5674 series plugs. Looks like the R5674's are projected tips, & the R5673's are not.

(1) Is there some reason why I should use projected tip plugs, for my app ?

(2) Advantages & disadvantages of each type.

Considering a #6 or #7 heat range.

(1) What would likely be the best NGK heat range, for my app ?

(2) Which heat range would be less likely to foul, with lots of in-shop starting & tuning, or would it make a difference ?

Any other $2 non-resistor plugs out there that are better than these NGK's ?

Not interested in any fancy, high dollar plugs. But, help with these specific questions would be appreciated.

PS: Please don't tell me to do a search. Almost every topic here has been discussed MANY times. We all like current info & fresh discussions, REGARDLESS of how many times the subject has been covered before.

[ta man]

Find AC DELCO r44's or r45's

[ponyakr]

Originally Posted by ta man

Find AC DELCO r44's or r45's

So, what would be the part numbers for NON-resistor AC's ?

[johnta1]

44S or 45S
The 'R' means resistor

[johnta1]

Those NGK's you posted are too long threads?

Something like R5670-5 would be the short threads I think.



I also liked the projected tip plugs for the heads.

[Steve C.]

Interesting tid bit.....

Market Share in the US
The companies holding the largest market share in the Spark Plug Manufacturing industry include DENSO Corporation and NGK Spark Plugs (USA) Inc.


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[ponyakr]

Originally Posted by johnta1

Those NGK's you posted are too long threads?

Something like R5670-5 would be the short threads I think.



I also liked the projected tip plugs for the heads.

Those are gasket seat plugs. As mentioned, I have 6x-8 heads, which require the 14mm tapered seat plugs.

https://www.summitracing.com/parts/ngk-2298/

Here are the Autolite #26 plugs that were in the engine when I got it. They are 14mm, tapered seat, .460 reach, projected tip, resistor, heat range 6.

https://www.summitracing.com/parts/a...xoCU9kQAvD_BwE

What would be the advantage/disadvantage of projected tips, in my app ?

[ponyakr]

Originally Posted by johnta1

44S or 45S
The 'R' means resistor

I think a 44TS or 45TS would be the tapered seat plugs I'd need. Did a search for 'em. Apparently they are no longer made. All I found were some NOS on Ebay, & a few singles left at Rock auto. When you Google those numbers, what you get mostly are links to R44TS or R45TS, resistor plugs.

https://www.ebay.com/p/1825005986?ii...BoCBu8QAvD_BwE

OK, I think the R in the NGK part numbers means Race. At least the one's I posted are non-resistor.

Also found that the heat range numbers are backwards. Higher NGK numbers are cooler, lower numbers are hotter. According to this first site, the heat range of Autolite plugs is hard to compare with other brands.

https://www.ngk.com/learning-center/...nversion-chart

https://www.briskusa.com/spark_plug_...at_range_chart

https://www.sparkplugs.com/learning-...or-hotter-plug

https://www.dragzine.com/tech-storie...-from-opinion/

[Half-Inch Stud]

my read on crooked AC Delco Plugs are those were hecho en mehico

[Sirrotica]

Working in a various GM dealerships over the years I've seen plenty of defective brand new AC plugs. And yes 2 brand new ones that the ceramic blew out as soon as the engine was fired up. One hit a cement block wall and took a good size nick out of the block.

I've always used Champion plugs because Milt Schornack used them at Royal for the Bobcat tune. They've worked really well for me, but just as any other brand, QC is now probably crap too.

My fathers 63 Bonneville used to always foul #6 plug with ACs, after switching to Champion it never fouled out that plug for years after that until the car got scrapped in 1972, the plug never fouled again.

I did a tune up in a Mazda piston engine back in the late 70s and had 2 brand new dead champion plugs, that was the only time I had a defective Champion plug in many years of installing them. As Mike said they all screw up at some point.

People have reasons for brand preference, those are my reasons.

[ponyakr]

So, if I go with NGK non-resistor plugs, should I get projected tips ?

And what heat range ?

Hey, these are all the same price, so I'd like to buy the best ones for my app, the first time.

One online article said that a rule of thumb, for slightly modified engines, is to go 1 heat range colder. So, I assume most 6X head cars came with R45TS type plugs, maybe ? If so, I assume that R44TS plugs would be one step colder. So, what NGK heat range would equal the heat range of an AC R44TS ?

[ponyakr]

Well, I suppose the word I'd use to describe my reaction to the response, or lack of it, that I've gotten from my questions on this thread is "surprised".

There are lots of guys here who go into GREAT detail, about many very technical subjects.

But, for the answers to my main questions, I'm hearing "crickets".

So, let me ask some different questions.

(1) Has anybody here run a strip only Pontiac powered bracket car, which had the later iron heads, such as 4X, 5C, or 6X ?

(2) Of those who have, what brand & number plugs did you run ?

(3) Did you ever change to a different brand, type, or heat range, to see if there was a performance difference ?

(4) Did you ever try non-resistor plugs ?

(5) Did you ever try plugs with non-projected tips ?

(6) Does anybody here know of any online articles, showing dyno or strip results comparing different types of plugs ?

[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 ?

[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.


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