Stumble

[Geoff 2]

As I also pointed out in post #118, the position/threads of the spark plug will affect how the plug body heats up & how the GS temp is affected.

 

[1STMP]

I have two or three NGK catalogs. None of them describe the GS colouration as a means of determining heat range. Nor have I seen any other plug manufacturers [ not mechanics ] use that description.

The colouring of the GS is dependant on a few factors/variables, as I described in post #118, making it unreliable.
From NGK catalog. I know the writing is small but the GS colour is not mentioned in any of the captions

View attachment 1527768

Straight from the horses mouth....
NGK
"The ground strap indicates the heat-range of the spark plug, and if the "color" of the ground strap changes too close to the ground strap's end, then the heat-range is "too cold," meaning that the strap is loosing heat too quickly to the base ring, and is not able to burn off deposits until near its end"
These guys are in the sole business
of designing and selling spark plugs.
I should think they know what they're
talking about.
Also, if clocking the ground strap
mattered, how would one install a
plug where it would be at it's optimal
position? Seems to me this would be
a great advantage to those seeking
maximum advantage for an engines
perfoamce. I guess that's why some
run EC-3's.

 

[Photon440]

Straight from the horses mouth....
NGK
"The ground strap indicates the heat-range of the spark plug, and if the "color" of the ground strap changes too close to the ground strap's end, then the heat-range is "too cold," meaning that the strap is loosing heat too quickly to the base ring, and is not able to burn off deposits until near its end"
These guys are in the sole business
of designing and selling spark plugs.
I should think they know what they're
talking about.
Also, if clocking the ground strap
mattered, how would one install a
plug where it would be at it's optimal
position? Seems to me this would be
a great advantage to those seeking
maximum advantage for an engines
perfoamce. I guess that's why some
run EC-3's.

Indexing washers are the usual method of locating the ground strap in the desired location.

Gapping and Indexing - NGK Spark Plugs

What does gapping and indexing mean for you? Check out this article to learn more about spark plug gap tolerances and indexing for race applications.

ngksparkplugs.com

 

[1STMP]

Indexing washers are the usual method of locating the ground strap in the desired location.

Gapping and Indexing - NGK Spark Plugs

What does gapping and indexing mean for you? Check out this article to learn more about spark plug gap tolerances and indexing for race applications.

ngksparkplugs.com

Thanks. Learn something new every day.
Do you use them?

 

[Geoff 2]

I could not find any info on the web that comes from NGK talking about ground strap colour.

The Bosch Automotive Handbook, 9th edition, 1500+ pages has 5 pages on spark plugs. Nowhere is ground strap colour mentioned. What is mentioned is the working temperature range of the centre electrode, which should be between 500 & 900*C. Below 500, the electrode may not self clean. Above 900, it could overheat.

 

[1STMP]

I could not find any info on the web that comes from NGK talking about ground strap colour.

The Bosch Automotive Handbook, 9th edition, 1500+ pages has 5 pages on spark plugs. Nowhere is ground strap colour mentioned. What is mentioned is the working temperature range of the centre electrode, which should be between 500 & 900*C. Below 500, the electrode may not self clean. Above 900, it could overheat.

Geoff2,
Please don't get the wrong idea that
some here my be disagreeing with
what opinions/knowledge you
possess. We're all here to offer
suggestions to help others.
That little something they missed,
or those that have been thru the
the same symtoms and know from
past experience.
What I quoted from NGK was straight
from their website on how to read
a sparkplug.
The engineer in me could not help
but look up some info on indexing
washers. And as usual, benefits of
using them are all over the map.
I did learn that indexing plugs has
a main purpose of clearance between
the GS and a domed piston, that
there's no definitive proof that indexing
results in a cleaner burn (thus a
cleaner burn of deposits on the GS),
or that indexing increases
horsepower.
I've as well as most here have pulled
a set of plugs only to find that deposits
and wear are identical, no matter how
they were indexed.
Put your thinking cap on and let's help
the OP resolve his issue.

 

[Geoff 2]

OK. But where is THAT quote on NGKs website. I have looked for it & could not find it.

 

[1STMP]

OK. But where is THAT quote on NGKs website. I have looked for it & could not find it.

Geoff 2,
I've wiped the history from my phone.
I could find it again but will take some
time.
If you zoom in tight to the GS over
the electrode (post #32) you can see
where the GS is discolored at the tip.
Also notice there is a notch developing
in the GS over the electrode. It's slight
at this point, but it's there. This is a
definite indication of a plug that is
rated too cold and concentrating heat
at the tip of the GS.
I'll poke around again tomorrow to see
where I can find NGK's explanation
I copied.

 

[1STMP]

OK. But where is THAT quote on NGKs website. I have looked for it & could not find it.

After searching again, I found this
from NGK:
"Proper heat-range is when the "color" is at the halfway point on the strap, neither too cold or too hot."
What I posted previously was a
summary from NGK with no direct
link back to their site.
Here is another site that states
the same.

How to read Racing Spark Plugs - Dragstuff

Learn how to read racing spark plugs for fuel ratio and timing.

www.dragstuff.com

 

[Aron Gleason]

After searching again, I found this
from NGK:
"Proper heat-range is when the "color" is at the halfway point on the strap, neither too cold or too hot."
What I posted previously was a
summary from NGK with no direct
link back to their site.
Here is another site that states
the same.

http://[URL]https://www.dragstuff.com/techarticles/how-to-read-plugs.html

[/URL]

According to what they're saying about the gs color. My plug is too hot. Meaning I should try a ngk 6 plug.

 

[1STMP]

Change of color confined at the tip
of the GS (about the same length/
diameter as the electrode) denotes
a cold heat range.
From what I could see with a cel
phones visual capacities, it looks to
me that you should drop down a
notch on the heat range.
Have you pulled all 8 and inspected
them?

 

[Aron Gleason]

Change of color confined at the tip
of the GS (about the same length/
diameter as the electrode) denotes
a cold heat range.
From what I could see with a cel
phones visual capacities, it looks to
me that you should drop down a
notch on the heat range.
Have you pulled all 8 and inspected
them?

Just the driver's side. They all show the timing mark close to where the strap is welded.

 

[1STMP]

Just the driver's side. They all show the timing mark close to where the strap is welded.

Thanks. Then you are correct, Up 1
range. I'd pull the other 4 and do
an overall comparison.
Have you had a chance to mess with the carb?

 

[Aron Gleason]

Thanks. Then you are correct, Up 1
range. I'd pull the other 4 and do
an overall comparison.
Have you had a chance to mess with the carb?

I haven't done anything since last Saturday. Been sick with the flu.

 

[1STMP]

I haven't done anything since last Saturday. Been sick with the flu.

Man, that sucks.
You starting to feel any better?

 

[Aron Gleason]

Man, that sucks.
You starting to feel any better?

A little, but hopefully by Monday I'll be back to normal.

 

[Geoff 2]

The GS colouring is an 'opinion', not from NGK Japan direct, nor any other plug manufacturer. That is because GS colour is not a reliable way of determining heat range because of the variables that will affect it, as mentioned in post #118.
The correct way to check heat range is to look at the colour transition of the insulator on the centre electrode; nothing to do with the GS. It is the centre electrode that can be too cold...or too hot, not the GS.

Well known racer Steve Morris of SM racing engines has a 6 min video on plug reading. He claims the GS colouring is related to ign timing [ not correct either ] & has nothing to do with heat range.

You will get lots of opinions...& little fact.

Aron.
Your plugs are not too hot based on the pics. Colder plugs would be a retrograde step.

 

[1STMP]

The GS colouring is an 'opinion', not from NGK Japan direct, nor any other plug manufacturer. That is because GS colour is not a reliable way of determining heat range because of the variables that will affect it, as mentioned in post #118.
The correct way to check heat range is to look at the colour transition of the insulator on the centre electrode; nothing to do with the GS. It is the centre electrode that can be too cold...or too hot, not the GS.

Well known racer Steve Morris of SM racing engines has a 6 min video on plug reading. He claims the GS colouring is related to ign timing [ not correct either ] & has nothing to do with heat range.

You will get lots of opinions...& little fact.

Aron.
Your plugs are not too hot based on the pics. Colder plugs would be a retrograde step.

Geoff 2,
As mentioned in previous posts, I'm
no expert on the tuning of Hollies.
The info I copied was from NGK
and I have no control over your
acceptance of that info.
We're not here to argue differences.
I argue that NGK would have a better
definition of what the readings are of
their spark plugs. I found the info.
This is just a piece of the puzzle
concerning the OP's original request
and you should concentrate on that
instead of fighting with me.
I offer my help as I was able to get
a larger than acceptable carb to
work when most told me it would not
work. I'll admit it took several
attempts, but, by gosh, she runs like a
bat out of hell.
There are ways to de-tune a Holley
where it's performance is acceptable.
The OP has a starting point. Let's go
from there. All we've heard from you
is there's no way to make the OP's
combo work, and the reputable
company that sold him the carb
says it will. Let's run on that premise.
By the way....
Feedback from the OP has verified
that his spark plugs are too high
of a heat range and I'm willing to
accept that info even though I
may have been incorrect in my
diagnosis. And we still don't know
the full story, as the OP has only
pulled one bank of plugs for a fair
comparison.

 

[Geoff 2]

1STMP,
You have not provided a link from NGK that says that GS colour is an indication of heat range.

I will keep arguing the point because you are suggesting going to a colder heat range....& I am saying he has the correct heat range. Fitting colder plugs is commonly done & is very often the wrong move.

I said early in this thread that this carb is too big & the stumble will NEVER be able to be fully eliminated. The single plane intake is making it worse. Unless the engine is winding to 7500+ rpm, it cannot use 950 cfm; & that is assuming 100% VE at 7500, which it will not be.

There are certain laws of physics that come into play....& not even Chrys engines cannot beat those!!

Stabbing the throttle on a carb with large throttle bores is not going to generate enough air speed to get fuel flowing...result is a stumble/bog. The large plenum of the single plane intake makes it worse because the signal has to 'fight' it's way through that large mass of air. I used the same M1 intake on a 440 I built two years ago & I made a turtle for the plenum floor to soak up some plenum volume because it was so huge. That engine has a 850 TQ on it. No stumble, as the small pri/triple boosters have high air speed....& get the fuel flowing. The air valve secondaries means the engine only takes the extra air when it needs it...& is not forced to take air as with a DP carb.

 

[1STMP]

1STMP,
You have not provided a link from NGK that says that GS colour is an indication of heat range.

I will keep arguing the point because you are suggesting going to a colder heat range....& I am saying he has the correct heat range. Fitting colder plugs is commonly done & is very often the wrong move.

I said early in this thread that this carb is too big & the stumble will NEVER be able to be fully eliminated. The single plane intake is making it worse. Unless the engine is winding to 7500+ rpm, it cannot use 950 cfm; & that is assuming 100% VE at 7500, which it will not be.

There are certain laws of physics that come into play....& not even Chrys engines cannot beat those!!

Stabbing the throttle on a carb with large throttle bores is not going to generate enough air speed to get fuel flowing...result is a stumble/bog. The large plenum of the single plane intake makes it worse because the signal has to 'fight' it's way through that large mass of air. I used the same M1 intake on a 440 I built two years ago & I made a turtle for the plenum floor to soak up some plenum volume because it was so huge. That engine has a 850 TQ on it. No stumble, as the small pri/triple boosters have high air speed....& get the fuel flowing. The air valve secondaries means the engine only takes the extra air when it needs it...& is not forced to take air as with a DP carb.

I humbly accept your expertise. You'll
get no argument from me.
I guess a very well known vendor
selling carbs to it's customers has
no clue as to what will work, or not,
under any given combo. Instead of
arguing your points with me, why not
e-mail them to tell them they're full
of crap.
My only effort here, is to help the OP,
not to attack those offering the help.