The International Cessna^® 170 Association

What is the torque spec for the C-145 spark plugs? The Continental Overhaul Manual sez "tighten to specified torque"; but nowhere in this grossly overpriced pub can I find the number.

Couldn't fint a reference quickly myself but found this on the web.
Continental Eng 25-30 Ft Lb (300-360 In Lb)
Lycoming Eng. 35 Ft Lb

Here is a link to Sacramento Sky Ranch where they quote this info from a Champion Service manual: http://www.sacskyranch.com/faq_spark_plug/FAQ00010.html

TCM SIL 03-02A says, in part:

CAUTION: Failure to install a new spark plug gasket each time the spark plug (s) are installed may
result in incomplete sealing of the combustion chamber, loss of spark plug heat transfer,
spark plug over heating, possible pre-ignition / detonation and internal engine damage.
GENERAL INSTALLATION PROCEDURES:
In the event spark plug manufacturer’s instructions are not available the following procedure may be used.
1. Always install spark plugs with new copper gasket.
2. Sparingly apply anti-seize to the spark plug threads. DO NOT APPLY ANTI-SEIZE TO THE FIRST
THREAD.
3. Always use a six point deep socket.
4. Thread spark plug by hand into cylinder to within one or two threads of the gasket. If this is not
possible, cylinder head threads or spark plug threads need to be cleaned.
5. Torque spark plugs to 300 to 360 inch pounds using a currently calibrated torque wrench.
6. Handle spark plug leads with clean, dry hands.

George Highlight # 2 also, you have probably seen how some people apply anti-seize. You know the one's, if a little is good then alot is even better; now why is this thing missing?

gahorn wrote:TCM SIL 03-02A says, in part:

CAUTION: Failure to install a new spark plug gasket each time the spark plug (s) are installed may
result in incomplete sealing of the combustion chamber, loss of spark plug heat transfer,
spark plug over heating, possible pre-ignition / detonation and internal engine damage.
GENERAL INSTALLATION PROCEDURES:
In the event spark plug manufacturer’s instructions are not available the following procedure may be used.
1. Always install spark plugs with new copper gasket.
2. Sparingly apply anti-seize to the spark plug threads. DO NOT APPLY ANTI-SEIZE TO THE FIRST
THREAD.
3. Always use a six point deep socket.
4. Thread spark plug by hand into cylinder to within one or two threads of the gasket. If this is not
possible, cylinder head threads or spark plug threads need to be cleaned.
5. Torque spark plugs to 300 to 360 inch pounds using a currently calibrated torque wrench.
6. Handle spark plug leads with clean, dry hands.

"If a little is good,more is better,and too much is great!"

Eric

See, it was Eric.

There are at least two types of copper spark plug gaskets; the crushable type, which clearly should not be re-used and the solid ones.
Why can't the solid copper gaskets be re-used if they're not deformed ?
Rudy

Re-using the spark-plug gaskets would slow the constant influx of the pilot's money ,which we all know is what makes an airplane fly!

Eric

rudymantel wrote:There are at least two types of copper spark plug gaskets; the crushable type, which clearly should not be re-used and the solid ones.
Why can't the solid copper gaskets be re-used if they're not deformed ?
Rudy

The solid copper gaskets are the only type of gasket for aircraft spark plugs that I know of. There are no "crushable" ones used on aircraft.
When the solid gaskets are used, they are usually marred slightly, and may no longer be exactly flat. It's a simple matter to use a peice of safety wire and heat them with a propane torch 'til they anneal, then drop them into water or light oil. Then they may be reused. (Of course, most people simply look them over, and if they're not badly damaged, reuse them.)
The copper gasket performs two important functions. One, they seal any possible leaks between the spark plug and the cylinder because copper is a soft metal that will easily conform to any machining marks or irregularities in the cylinder boss or spark plug base. Secondly, and very important, copper is an excellent conductor of heat. This allows the spark plug to pass it's absorbed heat onto the cylinder where the cooling fins carry it away to the atmosphere. Your spark plugs are designated with a specific "heat range" than keeps it's electrodes operating within a narrow temperature range. This keeps them hot enough to stay clean, yet cool enough so as to not cause pre-ignition when the fresh fuel/air mixture is introduced to the cylinder. That copper gasket must be in good condition, without scaling or crusty oxidation on it in order to efficiently conduct that heat away from the plug.
New gaskets, (should you desire them) are cheap and readily available from Aircraft Spruce 877/477-7823. I buy a couple extra-dozen when I'm ordering something else from them, so I don't pay extra freight just for gaskets.

It's a simple matter to use a peice of safety wire and heat them with a propane torch 'til they anneal, then drop them into water or light oil.

I was going to bring this up earlier as well. At my last annual th eIA had a large coffee can of annealed "used" gaskets.

To anneal them, shouldn't they air cool? Dropping them in water would quench (harden) them and that is what we are trying to get away from in the first place. The light oil would be somehting in between quenching and annealing.

...just wondering if I remember my strength and materials class correctly...

Bruce[/quote]

>> ...just wondering if I remember my strength and materials class correctly...


you do.

I air cool mine but most everybody I know quenches them in water. I think it makes no practical difference because I don't think it's a heat-treatable alloy. We're annealing them to relieve the work hardening.

Off subject
Hey, Paul what did you do with those wings I sold you?

spiro wrote:>> ...just wondering if I remember my strength and materials class correctly...


you do.

I air cool mine but most everybody I know quenches them in water. I think it makes no practical difference because I don't think it's a heat-treatable alloy. We're annealing them to relieve the work hardening.

>> Off subject

Hi, Tim,

nothing yet. Taking up room in my garage. I've all kinds of useful space being occupied by Cessna parts awaiting my attention...

Copper and brass will work harden any time it is bent, crushed, stretched, etc. To anneal copper or brass you heat to red and quickly cool, as in water. It acts the opposite of steel, which will harden. Hand loaders will sometimes anneal the case mouths of shells by standing them in water, heating the mouth of the case then quickly tipping them over into the water. You can try it with a piece of scrap tubing and you will see what happens.

Well it's a good day when you learn something new! Thknas.

Bruce