more newb engine questions (spark plugs)

[delemorte]

So speaking to the old man last night he advised that i should not run this motor with the plugs that where put into it. He states they are "too cold" and that i should purchase and install "hotter plugs"...
WTF is he talking about? isnt a plug a plug essentially?
thanks.

[GofastRacer]

Here, this should help!..
SparkPlug Overview! (http://www.ngksparkplugs.com/techinf...s/techtips.asp)

[SmokinLowriderSS]

So speaking to the old man last night he advised that i should not run this motor with the plugs that where put into it. He states they are "too cold" and that i should purchase and install "hotter plugs"...
WTF is he talking about? isnt a plug a plug essentially?
thanks.
Not quite.
Spark plug "heat" relates to how fast it cools itself by conducting it's heat to the cylinder head metal.
A "colder" plug shunts it's heat away faster.
A "hotter plug does it slower.
A "too-hot" plug will risk being a hot-spot in the cylinder for detonation and dieseling (run-on).
A "too cold" plug will tend to foul up, but will otherwise cause no damage.
You need the middle spot in the 2.
Most spark plugs have several plugs identical except in this respect, a comon example:
The Big Chevy, Ac Delco R-44T
The "44" is the "heat range" reference number in this code.
An R-43T is 1 step "cooler", An R-42 is 2 steps.
An R-46 is 2 steps "hotter".
Other plug mfrs. code it differently, but the effect is the same.
On a full-throttle "plug coloration mixture test run", you can also determine the heat range of the plug by a "line" on the ground electrode where the tip heat discolors the steel. a "perfect" heat is the line at the bend in the electrode.
Closer to the tip, to cold (cooling too fast.)
On the side shank of the electrode, too hot.
general rules:
If you get plug fouling problems arround idle, install a hotter plug.
Detonation troubles (minor), try a step colder plug.
Nitrous oxide usage generally increases cylinder heat so much that generally 1 or 2 steps colder plug than "perfect" is a good practice to avoid detonation.

[delemorte]

Not quite.
Spark plug "heat" relates to how fast it cools itself by conducting it's heat to the cylinder head metal.
A "colder" plug shunts it's heat away faster.
A "hotter plug does it slower.
A "too-hot" plug will risk being a hot-spot in the cylinder for detonation and dieseling (run-on).
A "too cold" plug will tend to foul up, but will otherwise cause no damage.
You need the middle spot in the 2.
Most spark plugs have several plugs identical except in this respect, a comon example:
The Big Chevy, Ac Delco R-44T
The "44" is the "heat range" reference number in this code.
An R-43T is 1 step "cooler", An R-42 is 2 steps.
An R-46 is 2 steps "hotter".
Other plug mfrs. code it differently, but the effect is the same.
On a full-throttle "plug coloration mixture test run", you can also determine the heat range of the plug by a "line" on the ground electrode where the tip heat discolors the steel. a "perfect" heat is the line at the bend in the electrode.
Closer to the tip, to cold (cooling too fast.)
On the side shank of the electrode, too hot.
general rules:
If you get plug fouling problems arround idle, install a hotter plug.
Detonation troubles (minor), try a step colder plug.
Nitrous oxide usage generally increases cylinder heat so much that generally 1 or 2 steps colder plug than "perfect" is a good practice to avoid detonation.
Good info. i thought the only diofference in plugs where the gaps. Ill have to pull mine and see what exaclty they are. I would assume the plug should be marked with what kind of plug it is?

[H20MOFO]

My post suks compared to smokin but isn't it the last # ,in other words when you say 44 is colder than 46, It's a scale of 1-10. I always thought 7 was kinda "middle ground" I run a v-power ngk but maybe thats a whole nother thread.

[BDMar]

My post suks compared to smokin but isn't it the last # ,in other words when you say 44 is colder than 46, It's a scale of 1-10. I always thought 7 was kinda "middle ground" I run a v-power ngk but maybe thats a whole nother thread.
With NGK plugs a "9" is colder than a "6". Standard Mercruiser uses an NGK "6". A '7" is a good starting point for most applications.

[Jetaholic]

On a full-throttle "plug coloration mixture test run", you can also determine the heat range of the plug by a "line" on the ground electrode where the tip heat discolors the steel. a "perfect" heat is the line at the bend in the electrode.
Closer to the tip, to cold (cooling too fast.)
On the side shank of the electrode, too hot.
Actually, that discoloration on the ground electrode is your timing indicator.
Closer to the tip, too retarded (flame front created too late, piston too far up the bore for the flame front to spread throughout the combustion chamber, thereby heating the tip)
On the side shank of the electrode, too advanced (flame front created too early, piston far enough down the bore to give enough time to allow the flame front to spread all the way to the side shank)
The threads of the plug are your heat range indicator.