2002 harley fat boy spark plugs
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Road Warrior
Joined: Nov 2015
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From: anywhere
2002 harley fat boy spark plugs
My service manual tells me to torque my spark plugs to 12 to 18 ft. lbs. I know this is for when I install new plugs, but what torque do I use when I take the plugs out to check them and reinstall them
Thanks in advance
Thanks in advance
Road Warrior
Joined: Apr 2022
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From: Omaha
some say to go a little tighter than finger tight, then go a 1/4 turn. There is another thread on one of the harley forums where the OP called a spark plug manufacturer. I would not go to the documented torque spec since the crush washer is already crushed.
Seasoned HDF Member
Joined: Nov 2004
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From: Ottawa, CANADA
I always tighten them to 16 ft-lbs (halfway between 12 and 18). The crush washer makes no difference in the final torque. By the time you reach the torque spec it's crushed as much as it will ever be for that specified amount, and you're measuring the torque with the washer crushed.
Make sure you use the specified anti-seize, because that DOES affect the torque.
Cheers!
Make sure you use the specified anti-seize, because that DOES affect the torque.
Cheers!
Last edited by Clammy; Feb 9, 2024 at 09:40 PM.
Seasoned HDF Member
Joined: Sep 2008
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From: San Diego, CA
If you want to go by the book, this was on Champion's web site:
Screw in the spark plug finger tight until the gasket meets the cylinder head. Then tighten the plug as specified below:
(my note- there is a scale that shows how much to turn a plug after finger tight, based on thread size. Both 12mm threads and 14mm threads show 1/4 turn))
PLEASE NOTE:
The 2002 Fatboy Twin Cam engine uses a plug that's 12mm x 1.25mm threads, with a gasket.
Champion used to make the Harley Twin Cam 6R12 plug (unsure if that has changed in recent years). The Champion plug RA8HC is the exact same plug. As such, Champion recommends a torque value of 10-18ft lbs. or if no torque wrench, finger tight and then 1/4 turn on 12mm threads.
If you use a torque wrench on new plugs, make sure to adjust the torque down 20%-30% if you use anti-seize. I also stay towards the bottom of the recommended torque scale.
I personally don't use a torque wrench on re-used plugs or plugs with anti-seize on the threads. On these, I use the finger tight & 1/16- 1/8 turn standard. Remember, you have aluminum heads with aluminum threads...
I also use a thread chaser on the spark plug threads prior to spark plug installation... new or re-used.
On the subject of using anti-seize...
Almost all modern spark plugs use anti-seize threads with a Nickel or Zinc-Chromate plating. Most spark plug manufacturers DO NOT recommend the use of anti-seize when installing their spark plugs. Off the top of my head, I know both Champion and NGK recommend against using anti-seize when installing their plugs.
Hope some of this info helps...
"CHAMPION PLUG TORQUE SETTINGS
It is essential to tighten a spark plug to the specified turning angle or torque setting as torque directly impacts a spark plugs ability to remove heat from the combustion chamber. Over tightening can cause damage to the threads in the cylinder head and the threads of the spark plug, stress the spark plugs internal seal, or fracture the spark plugs insulator. Under tightening will prevent the spark plug from being properly seated on the cylinder head, resulting in insufficient contact with the head to transfer heat. Either of these would result in elevated combustion chamber temperatures, followed by pre-ignition and detonation.Proper Tightening Procedure
Clean the spark plug threads and ensure the cylinder head is clean of debris.Screw in the spark plug finger tight until the gasket meets the cylinder head. Then tighten the plug as specified below:
With a Torque Wrench:
To find Champion's recommended torque setting, please enter the spark plug number in the search box. While viewing the part detail page, click on the "specs" tab. If a recommendation has been made, it will appear under the "Specifications" heading.Without a Torque Wrench:
If a torque wrench is unavailable, finger tighten the spark plug, then use a plug wrench to tighten 3/8-5/8 turn on plugs with a gasket, 1/16 turn on plugs with a tapered seat.(my note- there is a scale that shows how much to turn a plug after finger tight, based on thread size. Both 12mm threads and 14mm threads show 1/4 turn))
PLEASE NOTE:
- Torque recommendations are for spark plugs with new gaskets.
- If using anti-seize compound, use sparingly and reduce torque by 30%.
- Champion has created their recommendations based on the general consensus of most engine manufactures. In the case of a discrepancy between the plug manufacturer and engine manufacturers recommendations, always default to the engine manufacturer."
The 2002 Fatboy Twin Cam engine uses a plug that's 12mm x 1.25mm threads, with a gasket.
Champion used to make the Harley Twin Cam 6R12 plug (unsure if that has changed in recent years). The Champion plug RA8HC is the exact same plug. As such, Champion recommends a torque value of 10-18ft lbs. or if no torque wrench, finger tight and then 1/4 turn on 12mm threads.
If you use a torque wrench on new plugs, make sure to adjust the torque down 20%-30% if you use anti-seize. I also stay towards the bottom of the recommended torque scale.
I personally don't use a torque wrench on re-used plugs or plugs with anti-seize on the threads. On these, I use the finger tight & 1/16- 1/8 turn standard. Remember, you have aluminum heads with aluminum threads...
I also use a thread chaser on the spark plug threads prior to spark plug installation... new or re-used.
On the subject of using anti-seize...
Almost all modern spark plugs use anti-seize threads with a Nickel or Zinc-Chromate plating. Most spark plug manufacturers DO NOT recommend the use of anti-seize when installing their spark plugs. Off the top of my head, I know both Champion and NGK recommend against using anti-seize when installing their plugs.
Hope some of this info helps...
Last edited by hattitude; Feb 9, 2024 at 09:54 PM.
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HDF Community Team
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If properly torqued, the washer will have been compressed, but not crushed.
What torque are you recommending instead?
What torque are you recommending instead?
Grand HDF Member
Joined: Sep 2017
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From: Dubuque, IA
Or use NGK DCPR7E and don't use anti-seize. Its not necessary with NGK plugs and can be detrimental doing so.
Many a head have been stripped out NOT using it with champions.
https://ngksparkplugs.com/en/resourc...ut-spark-plugs
Many a head have been stripped out NOT using it with champions.
https://ngksparkplugs.com/en/resourc...ut-spark-plugs