Spark plug deposits
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Joined: Aug 2011
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Member
Joined: May 2012
Posts: 166
Likes: 0
From: Missouri
Year: 1996
Model: Cherokee
Engine: 4.0
Curious what the difference is between the NGK 7373 and the 7252 plugs? The 7373 looks to have a Projected Insulator Type vs the 7252 has a Non-Projected Insulator Type.
When I looked up my 96, it told me the 7252 was the correct ones.
What does this Projected vs non Insulator Type do?
And what kind of issues would running a Projected in an application designed for a Non-Projected cause?
When I looked up my 96, it told me the 7252 was the correct ones.
What does this Projected vs non Insulator Type do?
And what kind of issues would running a Projected in an application designed for a Non-Projected cause?
Member
Joined: May 2012
Posts: 166
Likes: 0
From: Missouri
Year: 1996
Model: Cherokee
Engine: 4.0
Curious what the difference is between the NGK 7373 and the 7252 plugs? The 7373 looks to have a Projected Insulator Type vs the 7252 has a Non-Projected Insulator Type.
When I looked up my 96, it told me the 7252 was the correct ones.
What does this Projected vs non Insulator Type do?
And what kind of issues would running a Projected in an application designed for a Non-Projected cause?
When I looked up my 96, it told me the 7252 was the correct ones.
What does this Projected vs non Insulator Type do?
And what kind of issues would running a Projected in an application designed for a Non-Projected cause?
http://www.hotrodders.com/forum/spar...ip-221790.html
Spark Plug Basics
The spark plug has two primary functions:
To ignite the air/fuel mixture
To remove heat from the combustion chamber
...
It is important to remember that spark plugs do not create heat, they can only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat.
The rate of heat transfer is determined by:
The insulator nose length
Gas volume around the insulator nose
The materials/construction of the centre electrode and porcelain insulator
The spark plug has two primary functions:
To ignite the air/fuel mixture
To remove heat from the combustion chamber
...
It is important to remember that spark plugs do not create heat, they can only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat.
The rate of heat transfer is determined by:
The insulator nose length
Gas volume around the insulator nose
The materials/construction of the centre electrode and porcelain insulator
A projected style spark plug firing tip temperature is increased by 10°C to 20°C.
Member
Joined: May 2012
Posts: 166
Likes: 0
From: Missouri
Year: 1996
Model: Cherokee
Engine: 4.0
More info.
The P, with the projected tip, will tend to run cleaner and cooler.
The non-projected type of plugs are said to reduce compression ever so slightly, as well as start the flame closer to the top of the cylinder head.
Thread Starter
Junior Member
Joined: Apr 2012
Posts: 89
Likes: 0
From: Tampa
Year: 1993
Model: Cherokee
Engine: 4.0
Shop is going to fix my plugs next week. Had no insight as to why number 2 and 6 look fine but the rest have ash deposits.
I'm about to go out and spray some carb cleaner.
I'm about to go out and spray some carb cleaner.
Thread Starter
Junior Member
Joined: Apr 2012
Posts: 89
Likes: 0
From: Tampa
Year: 1993
Model: Cherokee
Engine: 4.0
My jeep doesn't care for the 7373's, I ran it to work and back today. MPGs seem lower(maybe), and it idles slightly rough.
No effects from the carb cleaner, except for a cleaner intake lol.
I did some reading, and with the ash deposits being on just one side of the plug, that points to the valve seals leaking.
I'm going to go rent a compression gauge after dinner.
No effects from the carb cleaner, except for a cleaner intake lol.
I did some reading, and with the ash deposits being on just one side of the plug, that points to the valve seals leaking.
I'm going to go rent a compression gauge after dinner.
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