[Scott65]

As promised, here is the consolidation of information from the spark plug thread last week(ish). And, simply put, that's ALL it is. It is not a recommendation THAT you change, or a claim that one is better than the other.
Things to keep in mind:
1.) This is NOT intended to be a comprehensive spark plug cross reference! Those are available elsewhere. This is only to cover popular Pontiac applications, as a convenience to NOT having to search those. It is focused on NGK as their numbering methods do seem more confusing to folks.

2.) This discussion took place in the STREET forum, and originated in the form of a question about plugs for Edelbrock heads. So this will stay within that general realm, and without discussion of the racing plugs. I am including a link provided by johnta1, that would be helpful for those interested in that.

https://www.dragstuff.com/techarticl...reference.html

We covered the Edelbrock(and possibly other Alum. heads that use the same plug construction), pre '71 gasketed, and later tapered seat plugs.
Attached is an image with the cross information, and an NGK nomenclature document(pdf) The cross reference information provides an NGK starting point from a known quantity in other brands. The pdf should help those interested in experimentation with materials i.e. taking the known nickel/copper plug provided and finding an iridium etc. if so desired.

I am NOT a computer person...There, I said it... I made an excel spreadsheet, because I thought it would be neat and orderly(nice rows and columns) and easy to see and use. Unfortunately, it's not a supported file for upload(at least the way I did it, and this size) SO, what you have here is, my best effort at a carefully cropped screenshot of it that I hope will be useful still. It does print nicely in landscape, for me anyway...
To any of you, members, mods, administrators, who have the skills to improve the appearance, while maintaining the accuracy, or have the necessary permissions to directly upload the original document to the site, or use some kind of hosting site to provide it, feel free(I'll send you the original). This isn't mine, I just grouped it together in one place.
Bart said he'd leave it for a while, then sticky it, if appropriate, and deemed worthwhile. So there should be time for improvement if needed, or desired. But not by me, this my contribution...
Alternatively, if it's helpful with no extra improvement required, Bart could delete everything after the link(my ramblings) and sticky it

Hope this is helpful for someone. Thanks to all who contributed and Formulajones for proofing my spreadsheet.

[Scott65]

Update... I did forget to check the appearance in mobile view, but did just now. Looks like it works there too, so that's a plus. (And just luck on my part, but I'll take it!)

[ZeGermanHam]

Where to NGK R5674-6 plugs fit into the picture?

[Scott65]

Originally Posted by ZeGermanHam

Where to NGK R5674-6 plugs fit into the picture?

Racing plugs... Check out the link provided for those. I believe non resistor. 6 heat range. But not really the target of the info here.

[ZeGermanHam]

Ah, gotcha. Please forgive my total ignorance on this topic, but what are the drawbacks of running the R5674-6 plug in my low-compression 400ci? I bought them from Butler simply because their website said they were suitable for a pump gas engine with "normal" (i.e., not high) compression.

[1968GTO421]

Originally Posted by ZeGermanHam

Ah, gotcha. Please forgive my total ignorance on this topic, but what are the drawbacks of running the R5674-6 plug in my low-compression 400ci? I bought them from Butler simply because their website said they were suitable for a pump gas engine with "normal" (i.e., not high) compression.

On a phone call with Butler, I was recommended the same plugs (R5674-6) for my 428 w/ 6X-4 heads and "normal" compression. Same questions as above ^. I'm running MSD distributor with the "old" analog 6AL box so I think these plugs will fire fine (or will they?) . Thanks for the advice.

[Scott65]

I don't think there's a problem with them as long as rfi isn't a concern. And I'm no authority on that application, I "think" the racing plugs are non resistor. I, and others with sensitive electronics would do better to stick with a resistor version.

[ZeGermanHam]

You are correct that the R5674-6 plugs are resistor-less. In my case, I'll be running them with a Performance Distributors D.U.I. HEI distributor. I'm not running any other sensitive electronics, so hopefully RFI shouldn't be a factor.

Thanks for the info, and for taking the time to pull some plug info together!

[1968GTO421]

I'm having a "stupid" day. Is there a resister verson of the R5674-6 plugs that you know of or is there a site where I can find this info. I've looked at the NGK site and came away confused.
If I'm using resister wires (spiral bound, etc) will that generally resolve any RFI issues from the plugs?
Thanks.

[Scott65]

Originally Posted by 1968GTO421

I'm having a "stupid" day. Is there a resister verson of the R5674-6 plugs that you know of or is there a site where I can find this info. I've looked at the NGK site and came away confused. Thanks.

I believe, if you look in the chart attached, it lists a UR6 in that application. It will be resistor, heat range 6, and have an extended tip, where the R5674-6 is likely NON projected tip. But that's a guess, as I don't use them.
All the ones we included on the chart should be resistor version, projected tip, for the heads listed.
ETA: The control factor is, we started from known resistor style, projected tip plug, of a known existing plug to cross from. NOT the racing plugs. But it is still a pretty simple cross once you understand the starting point. The NGK "5" heat range is ~= to Autolite 24. NGK "6" an Autolite 23. Bigger gets colder, smaller gets hotter.
To go from an NGK racing non resistor, the "-6" is the heat range, 6, look for a resistor version in heat range 6 also. In the example above, UR6...

[johnta1]

Send me the xlsx file and I can put it on my site where it can be downloaded from a link.


johnta1@wallaceracing.com

[1968GTO421]

Scott, Really appeciate the help. I'll try a different method to download your charts and that should help alot. And thanks for all your work on the charts! Once I get them printed out where my ancient eyes can read them better, all will be well.

[Scott65]

Originally Posted by 1968GTO421

Scott, Really appeciate the help. I'll try a different method to download your charts and that should help alot. And thanks for all your work on the charts! Once I get them printed out where my ancient eyes can read them better, all will be well.

No problem. The screenshot printed well for me in landscape and was not too bad size wise.(I didn't try it without my bifocals... but I can't read anything without them anyway)
John has offered to host the document. From it's original condition, it printed as 2 sheets, so maybe that will help. Thanks to John for that. ( and I did send it, fyi)

[johnta1]

NGK Excel file


Right click and 'save as' should work.

[Scott65]

Thank you John

[Formulajones]

Glad to see you got this up Scott

Those R5674-6 plugs are in fact the racing plugs that are non-resistor. In the plug thread that Scott mentioned earlier we briefly talked about those because I pulled a set out of dad's engine that Tony Bischoff installed.

Dad had already been running EFI with them and having no issues but I never liked the plug design to start with so I wanted to take them out. They are of the non projected tip variety which we always used to call "oil burnin' plugs"
Personally I prefer extended tip electrodes to put the spark out in the combustion process further. That and I would rather run resistor plugs anyway so because of those 2 reasons those were pulled for a set of BKR6E's.

[Goatracer1]

Thanks for the chart. I asked the original question and this helps more than anything I found on NGK's site.

[Scott65]

Glad to help. Hope you find benefit from the available NGK options.