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Discussion Starter #1
So, for the majority of my petrol-head forming years, my (old school) father was of the opinion that Champions were crap and that NGKs were the best... (I think that at some point a bad/worn/burned old Champion must have screwed him over on the side of the road one night and he just simply never recovered from it...) :D

Consequently, I have a good feel now for the temperature-ranges of NGKs. I don't though for the others such as Bosch, Denso, Autolite etc... :eek: Any way, I think that the stock 24 valve cars call for an NGK R (somewhere LOW down - like a 6...) Cross-referencing that with an Autolite (that I have been using in the 164 LS/Qs with good success), I see that their temp ranges go hotter as their numbering goes up - 1 is cold and 3 is hot and then that's it...!? :confused:

Also, the 24 valve has this funky small wrench-head on it too and not any plug-socket can fit in the hole (no room for a plug-wrench to fit around it - so there are several variables here!) Any way, I was running the Autolite Double Platinums in the 3.7 race car (and that plug is already at - what they would consider - the cold end of their range!)

I was getting the 3K stumble that feels like spark-scatter and we think that the smaller plug-gaps will take care of this, but Dawie wants me to run an 8 (on an NGK scale) at a minimum and preferably a 9! Can't find any here! He also mentioned a c63c Champion, but I think that it plays out to be an 8 on the NKG scale!

Can somebody please suggest a 9 that would fit?
 

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Discussion Starter #2 (Edited)
As a cross-reference;

NGK BCP7ES is the right fit for the 24 valve head (and my high-compression setup for that matter) - as are Autolite APP 3923 - I think that they are part number 2613! I spent a good part of the afternoon staring at manuals and now I have a headache!

Saw a cross-reference for an NGK R5671A-8 (part number 4554) and R5671A-9 - part number 58?? - that they say fits... Since these are from the R range of the NGK catalogue, can I consider those last digits to represent a temp range of 8 and 9 respectively - similar to their traditional range of plugs???

By the way - 12.0:1 compression on race gas with fully-programmable fuel and timing...
 

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Richard Jemison
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Racing plugs

The pics attached are of 3 race plugs, with two stock type on the right.
I only used the Bosch Super B241 09 6936 (dome surface gap) and early on the Champion N57 & 59. All were designed for aluminum heads, and have 5/8 hex. Easy in & out.
The Bosch plug was faultless. And no ceramic or electrode to burn or detonate apart.
 

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Discussion Starter #5
Thanks guys - ended up getting some NGKs from their racing "R" range... -8 and -9... We'll see next week.
 

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When you say "R" range, do you mean as in "EGV" ending (palladium, narrow tip) or as in BCP-R which means "Resistor" as in Radio safe?

Also please not that tip protrusion is very important, it will affect ignition timing quite a bit. A protruding tip will act as more advance.


I see NGK are quite confident in their design "...in turbocharged engines with power boosts of 50% or more."
Compared to igniting it with a match?
 

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Seems like the NGK plugs are next to flawless. We used the stock NGKs in a supercharged 355 Chevy (350 bored .30 over) that we were running a bit hard. It had an MSD mag system and ran on alcohol with a bit of nitro thrown in. That car would run a 3.9 second 1/8 mile with a .9 sec 60 foot. It was pretty quick and the plugs were never changed in a season of screwing around. We would check them and they were always fine so we left them in. I'm sold. I have used them in all my cars for years.
Paul
 

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Discussion Starter #8
I was out at the Performance Racing Industry (PRI) trade show in Orlando last week and dropped in on the NGK booth there. Got all the dope I need for now.

So, say on a 24 valve BCP R 6 ES plug for example;

BC = A 14mm thread on a 5/8" (16mm) hex size
P = A projector insulator (versus say a compact, or surface discharge type.)
R = Resistor type plug
6 = the heat rating with 2 the hottest and 12 the coldest
E = Thread reach - 19mm in this case (3/4")
S - A standard 2.5mm diameter center electrode

In the "R" plugs that I got ("R" is for "Racing" and not to be confused with "R" as in "Resistor-type" in the plug mentioned above) Those are from their racing-series plugs (within their V-Power family) and they don't offer warranties on those BTW (due to the application...)

The R 5671A-8 and -9 that I am going to try in the 3.7 have specifications that cross-reference back to the BCP R 6 ES mentioned above for example (other than the fact that they have a much colder heat-range for a higher compression/race-gas engine.)
 
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