spark plug gap?
12-23-2005, 08:22 PM
#1
17,16,15,14,13,12,11 Drvr
Thread Starter
iTrader: (10)
Join Date: Aug 2003
Location: Mont Belvieu, Texas
Posts: 6,713
Likes: 0
Received 0 Likes
on
0 Posts
spark plug gap?
ok so if the plug is gapped at .35 its a colder spark? and if its gapped at .60 its a hotter spark? confused, some say the closer the the gap the hotter it burns and the farther its apart the colder it burns or is it a more controlled spark with it closer? 
so
so
12-24-2005, 06:44 PM
#3
Baltimore Whore
iTrader: (95)
Join Date: Apr 2004
Location: In a van DOWN BY THE RIVER
Posts: 16,820
Likes: 0
Received 2 Likes
on
2 Posts
The gap has to do with how well the spark ignites the mixture with reguard to how much juice the ignition system can provide. A hotter plug sticks in the combustion chamber farther then a colder plug.
12-24-2005, 11:38 PM
#6
17,16,15,14,13,12,11 Drvr
Thread Starter
iTrader: (10)
Join Date: Aug 2003
Location: Mont Belvieu, Texas
Posts: 6,713
Likes: 0
Received 0 Likes
on
0 Posts
I have the gap tool lol, just need the info for what is the hotter burn .35 or .60, like i said some people say the closer the gap is the hotter the burn is, is that right? or is it the closer the gap the colder the burn???? they say when you run nos to get tr6's and there gaped at .35 for a colder burn confused on this part lol
12-25-2005, 12:08 PM
#7
Tribe Shaman
iTrader: (4)
Join Date: May 2004
Location: Texas
Posts: 3,050
Likes: 0
Received 0 Likes
on
0 Posts
it depends on the plug it self and what is on the inside.
some are made to deliver a hotter spark and others are made to deliver a colder spark.
i know on some plug types you can burn a hole in your piston very easy because the rating on them is just too hot.
the smaller gap insures fire with out blow out under boost and under high compression in the upper rpm range.
some are made to deliver a hotter spark and others are made to deliver a colder spark.
i know on some plug types you can burn a hole in your piston very easy because the rating on them is just too hot.
the smaller gap insures fire with out blow out under boost and under high compression in the upper rpm range.
Trending Topics
12-25-2005, 01:02 PM
#8
11 Second Truck Club
iTrader: (31)
Join Date: Jan 2005
Location: Breaux Bridge, LA
Posts: 5,861
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by mangledgmc03
The gap has to do with how well the spark ignites the mixture with reguard to how much juice the ignition system can provide. A hotter plug sticks in the combustion chamber farther then a colder plug.
12-25-2005, 06:45 PM
#9
This bit of info came off of NGK's website:
"Too much gap can result in a higher rate of misfires, loss of power, plug fouling and poor fuel economy. It is always best to check the gap against the manufacturer's specifications.
Another consideration that should be taken into account is the extent of any modifications that you may have made to the engine. As an example, when you raise compression or add forced induction (a turbo system, nitrous or supercharger kit) you must reduce the gap (about .004" for every 50 hp you add). However, when you add a high power ignition system (such as those offered by MSD, Crane, Nology) you can open the gap from .002-.005"."
"Too much gap can result in a higher rate of misfires, loss of power, plug fouling and poor fuel economy. It is always best to check the gap against the manufacturer's specifications.
Another consideration that should be taken into account is the extent of any modifications that you may have made to the engine. As an example, when you raise compression or add forced induction (a turbo system, nitrous or supercharger kit) you must reduce the gap (about .004" for every 50 hp you add). However, when you add a high power ignition system (such as those offered by MSD, Crane, Nology) you can open the gap from .002-.005"."
12-25-2005, 07:31 PM
#10
TECH Fanatic
Join Date: Oct 2005
Location: Woodstock Ontario Canada
Posts: 1,379
Likes: 0
Received 0 Likes
on
0 Posts
I always thought that in the reference to hotter or colder plugs was the plugs ability to conduct heat from the plug itself into the cylinder head, thus into the engine's coolant. A cold plug transmits heat quicker into the head, a hotter plug is actually hotter because it transmits heat more slowly into the cylinder head.
In nitrous/forced induction you want to use a colder plug or the electrode will start to act as a glow plug pre-igniting the a/f charge ahead of schedule. This gives you detonation.
The colder plug will get the heat from the electrode into the plug, then into the head faster than a colder plug. The colder plug doesnt transmit this heat fast enough into the head, so it backs up and starts to make the plug electrode to glow.
You run smaller gaps with nitrous and forced induction because the increased cylinder pressure makes the atmosphere inside the combustion chamber more dense and can cause the spark to not jump across the gap. This is because under pressure there are more molecules to be ionized for the spark to travel thru. You either have to increase voltage or decrease the number of molecules the spark must ionize, you do the latter by reducing plug gap.
If you close the gap too much, not enough molecules will be exposed to the spark and the flame kernel may "blow out" before the a/f charge is completely combusted, thus power production drops way off, and emissions go thru the roof.
If you have too cold of a plug, deposits will not be burned away and the plug will foul rather quickly. A happy median between plug fouling and pre ignition must be found.
I am almost 100% sure you cant make a plug colder or hotter by changing its gap, the heat range of a plug is determined at the time of manufacture by the amount of material between the electrode and the threads. The threads of the plug along with the seat of the plug is where the heat is transferred from the plug into the cylinder head thru conduction.
The smaller the gap, the easier the spark is conducted from 1 electrode to the other because there isnt as many molecules for it to travel thru. The greater the gap, the more molecules are present between the 2 electrode thus the more difficult it is for the spark to travel.
If there are too many molecules to, too high a cylinder pressure, or too much gap, the spark may not travel from 1 electrode to the other at all, thus a spark doesnt occur at all. Not good.
This why today's spark plugs have more gap than earlier ignitions, the stronger coils simply have more energy to penetrate from 1 plug electrode to the other, so the newer ignition can use more gap. More gap allows more molecules to be exposed to the spark, this produces a larger kernel around the plug which spreads throughout the combustion chamber.
Its like using either a match or a propane torch to light a campfire, the larger flame lights the campfire much easier. You want to use the largest spark you can get so long as the ignition has sufficient energy to jump the gap. remeber, no spark no combustion.
On a 1996-2000 Vortec 305, 350, 454 and 1996-2005 4.3V6 without nitrous or forced induction (NA) run the recommended .060" of plug gap.
On the 1999-2006 Vortec 4.8, 5.3, 6.0, 8.1 that is NA run whatever GM recommends. These have much shorter plug wores, so GM can use either a smaller coil to jump the same gap, or the same coil voltage to jump a larger gap. This is because the coil energy isnt being wasted to overcome wire resistance. Ideally you would have a spark plug with a coil right on the end of it. The 1999+ coil on plug sustem comes pretty close though.
The older TBI engines had weaker coils than the newer Vortecs, thats why their plug gaps are smaller.
On ANY engine that uses nitrous or forced induction reduce plug gaps, I usually hear 0.035" of plug gap recommended to people. The supercharger, turbo charger or nitrous manufacturer should supply the prodcts user with a suggested plug gap.
Does this make sense to anyone??? Discussion???
Sorry for the long post.
peace
Hog
In nitrous/forced induction you want to use a colder plug or the electrode will start to act as a glow plug pre-igniting the a/f charge ahead of schedule. This gives you detonation.
The colder plug will get the heat from the electrode into the plug, then into the head faster than a colder plug. The colder plug doesnt transmit this heat fast enough into the head, so it backs up and starts to make the plug electrode to glow.
You run smaller gaps with nitrous and forced induction because the increased cylinder pressure makes the atmosphere inside the combustion chamber more dense and can cause the spark to not jump across the gap. This is because under pressure there are more molecules to be ionized for the spark to travel thru. You either have to increase voltage or decrease the number of molecules the spark must ionize, you do the latter by reducing plug gap.
If you close the gap too much, not enough molecules will be exposed to the spark and the flame kernel may "blow out" before the a/f charge is completely combusted, thus power production drops way off, and emissions go thru the roof.
If you have too cold of a plug, deposits will not be burned away and the plug will foul rather quickly. A happy median between plug fouling and pre ignition must be found.
I am almost 100% sure you cant make a plug colder or hotter by changing its gap, the heat range of a plug is determined at the time of manufacture by the amount of material between the electrode and the threads. The threads of the plug along with the seat of the plug is where the heat is transferred from the plug into the cylinder head thru conduction.
The smaller the gap, the easier the spark is conducted from 1 electrode to the other because there isnt as many molecules for it to travel thru. The greater the gap, the more molecules are present between the 2 electrode thus the more difficult it is for the spark to travel.
If there are too many molecules to, too high a cylinder pressure, or too much gap, the spark may not travel from 1 electrode to the other at all, thus a spark doesnt occur at all. Not good.
This why today's spark plugs have more gap than earlier ignitions, the stronger coils simply have more energy to penetrate from 1 plug electrode to the other, so the newer ignition can use more gap. More gap allows more molecules to be exposed to the spark, this produces a larger kernel around the plug which spreads throughout the combustion chamber.
Its like using either a match or a propane torch to light a campfire, the larger flame lights the campfire much easier. You want to use the largest spark you can get so long as the ignition has sufficient energy to jump the gap. remeber, no spark no combustion.
On a 1996-2000 Vortec 305, 350, 454 and 1996-2005 4.3V6 without nitrous or forced induction (NA) run the recommended .060" of plug gap.
On the 1999-2006 Vortec 4.8, 5.3, 6.0, 8.1 that is NA run whatever GM recommends. These have much shorter plug wores, so GM can use either a smaller coil to jump the same gap, or the same coil voltage to jump a larger gap. This is because the coil energy isnt being wasted to overcome wire resistance. Ideally you would have a spark plug with a coil right on the end of it. The 1999+ coil on plug sustem comes pretty close though.
The older TBI engines had weaker coils than the newer Vortecs, thats why their plug gaps are smaller.
On ANY engine that uses nitrous or forced induction reduce plug gaps, I usually hear 0.035" of plug gap recommended to people. The supercharger, turbo charger or nitrous manufacturer should supply the prodcts user with a suggested plug gap.
Does this make sense to anyone??? Discussion???
Sorry for the long post.
peace
Hog