What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Spark plug and adaptor torque

togaflyer

Well Known Member
Looking for install and torque setting for auto plugs and the adaptor.

EFII instructions say put the plug in the adaptor then torque the spark plug while in the adaptor to 30 lbs to set both the plug and adaptor.

EMag instructions say plug into the adaptor and then 18 lbs torque applied to the plug.

I have also read, plug in the adaptor, torque plug at 18, then torque adaptor at 20 lbs

I get the plug into the adaptor and then torque the plug in the adaptor, but big point spreed between 18 and 30 lbs.

So what is the tried and true method.

I’m installing Denzo spark plugs with a Surefly ignition and an auto plug harness set.
 
I follow emag specs. A quick web search indicates that both Champion and NGK say proper torque for a 14 mm plug in an aluminum head is 18-22 ft lbs
 
I’ll just note that I hope you meant ‘foot-lbs’, definitely not ‘in-lbs’.
As to torque values, there are lots of variables, such as recommended lubricant (or none), etc. And even TCM and Lycoming recommend different (25 and 35, ft-lbs, respectively) torques for standard aviation plugs, in very similar circumstances.
 
Also

When you settle on the number. I find it helps to scribble it in sharpie on the outside of the baffles for next time.
 
As another point of reference, Lightspeed provides the following guidance:
- Install adaptors in cylinder head using the supplied copper washer. Torque to 35 - 45 ft-lbs using anti-seize compound.
- Install automotive style spark plugs with their washer. Torque to 20 ft-lbs using anti-seize compound.​

Lycoming SSP-1776-5 (Service Table of Limits and Torques) says to torque the 18 mm spark plug to 35 ft.-lbs., so that is what I use for the 18mm adapter. (Lightspeed says 35 to 45 ft.-lbs. for the adapter)

Steve
 
Hey Bob, yes definitely foot pounds. I have been setting my aviation plugs at 30 ft pounds with a touch of anti seize on the first couple threads. Been doing this for decades. I understand that putting to much torque load on the adaptors can damage them. Also do you normally remove the adaptor when you pull the plugs for inspection?
 
I have wondered about this for quite a while and had a list compiled of the various instructions copied from their manuals.

Note, the adapter material for lightspeed. I remember a thread some time ago saying their adapters were superior and you should buy those.

Also note the variations on anti-seize.

Light Speed
-Install adaptors in cylinder head using the supplied copper washer.
Torque to 35 - 45 ft-lbs using anti-seize compound.
-Install automotive style spark plugs with their washer. Torque to 20 ft-lbs using
anti-seize compound.
Adapter material: "Made of high strength aluminum bronze"

SDS-CPI2
-Install plugs into adapters and slide the copper washer over the adapter.
-Thread the spark plug into the adapter 2. Torque the assembly into the cylinder head using the PLUG hex
to 19 ft./lbs.
-Torque the ADAPTER further to 25 ft./lbs. Use only a thin stripe of anti-seize compound
on the plug and adapter. Do not coat the threads.
Adapter material: "We provide brass adapters"

EFii
Always install the brass spark plug adapters onto the spark plug first and then install the assembly
into the cylinder. Never torque the spark plug adapters into the cylinder without a spark plug installed – this
could damage the spark plug adapter. With spark plugs and adapters installed into the cylinders, torque the
spark plug only to 30 ft lbs. This will seat the washers on both the adapter and the spark plug with one step.
Adapter material: "Brass"

Emag
First,install adapters with the supplied gasket on the spark plugs
finger tight.
Then, insert the combined assembly (plug with adapter) in the engine
and tighten to 18 ft/lb (standard auto plug torque) through the spark plug ONLY. Do
not torque the adapter itself.
Note 1: If you install and torque the adapters separately, stresses will be
focused at the adapter neck and can cause it to fail during installation.
Adapter material: I cannot find it stated anywhere
 
I have wondered about this for quite a while and had a list compiled of the various instructions copied from their manuals.

Note, the adapter material for lightspeed. I remember a thread some time ago saying their adapters were superior and you should buy those.

Also note the variations on anti-seize.

Light Speed
-Install adaptors in cylinder head using the supplied copper washer.
Torque to 35 - 45 ft-lbs using anti-seize compound.
-Install automotive style spark plugs with their washer. Torque to 20 ft-lbs using
anti-seize compound.
Adapter material: "Made of high strength aluminum bronze"

SDS-CPI2
-Install plugs into adapters and slide the copper washer over the adapter.
-Thread the spark plug into the adapter 2. Torque the assembly into the cylinder head using the PLUG hex
to 19 ft./lbs.
-Torque the ADAPTER further to 25 ft./lbs. Use only a thin stripe of anti-seize compound
on the plug and adapter. Do not coat the threads.
Adapter material: "We provide brass adapters"

EFii
Always install the brass spark plug adapters onto the spark plug first and then install the assembly
into the cylinder. Never torque the spark plug adapters into the cylinder without a spark plug installed – this
could damage the spark plug adapter. With spark plugs and adapters installed into the cylinders, torque the
spark plug only to 30 ft lbs. This will seat the washers on both the adapter and the spark plug with one step.
Adapter material: "Brass"

Emag
First,install adapters with the supplied gasket on the spark plugs
finger tight.
Then, insert the combined assembly (plug with adapter) in the engine
and tighten to 18 ft/lb (standard auto plug torque) through the spark plug ONLY. Do
not torque the adapter itself.
Note 1: If you install and torque the adapters separately, stresses will be
focused at the adapter neck and can cause it to fail during installation.
Adapter material: I cannot find it stated anywhere
Great summary!

If you want stronger adapters - not saying you need them - you can buy them in steel.

https://www.gsparkplug.com/1x-spark-plug-thread-adaptors-18mm-down-to-14mm-steel-m14-m18.html

I use the emagair method, and so far my spark plugs have stayed in the hole.

BTW, emagair adapters appear to be some kind of brass/bronze material.
 
Back
Top