Spark Plug Price

[W.J.Langholz]

A.E.R.O. has URHM40E for sale @13.50 ea for 12 or more is this a good price?

W.

[Brad Brady]

Anything under $20.00 is a good price. But those are Unison, aren't they?

[W.J.Langholz]

I read too fast...went back and brought up the main page and yes they are.

My annual is in april and I thought maybe I would put in a new set, all at the same time. I currently have some single and some double fine wire 38's and the last time I cleaned them I thought that maybe the next time they should be changed out. The ones that look good I would keep for spares. Always looking for a special on something

W.

[Zreyn]

23 years with this airplane & the only "spares" I ever needed were not spark plugs! One spark plug WIRE,one tail wheel tire&tube,one tail wheel spring.I finally threw out that box of spare spark plugs I was saving for years.
P.S. I guess we should be clear on what "spare" means. In this case I mean it is something that you need before you can can continue the trip.Although I will admit that I flew on home when I broke the tail wheel spring.

[W.J.Langholz]

You know I've done that too.....hang on to something forever, move it 2-3 times cause it's in the way, and as soon as I throw it out.....the next week I need it



W.

[Zreyn]

My hanger got so bad I had to recruit help from non airplane family members to clean it out.The dumpster is parked in front of the doors as we speak.

[GAHorn]

I read too fast...went back and brought up the main page and yes they are.

My annual is in april and I thought maybe I would put in a new set, all at the same time. I currently have some single and some double fine wire 38's and the last time I cleaned them I thought that maybe the next time they should be changed out. The ones that look good I would keep for spares. Always looking for a special on something

W.

Dubya,.. those on-sale are massive-electrode aren't they? (Your fine-wire plugs are much more expensive than massives. and they will outlast massives by a long shot, too.)

[W.J.Langholz]

George

You are correct on both issues. I just feel like I'm doing something half-A## by only replacing 3-4 out of 12, but @ $80 bucks a pop I wasn't feeling real good about 12 fine wire ones either. I'll look hard at them when I get them out.....I don't want to be in the would a, could a, should a, spot after I get it all back together and be on my way to a TIC170 outing.
The massives are advertised at 13.50 ea. so for 12 it would be like 4 fine wire ones.

W.

[GAHorn]

Yeah... fine wires can last an entire engine TBO if they are not aggressively sand/bead-blasted each annual/service period. More have been destroyed by eager cleaning than by actual wear as long as they are properly rotated to even-out the positive/negative firing sequences of magnetos.

[W.J.Langholz]

George
Could you explain the rotation thing, you lost me there. I put them right back in the hole the came from. As far as cleaning I try to watch as I clean and do a little picking between the blasting but yes I maybe at fault for being a bit aggressive. I afraid if I didn't have gloves on my fingers would be bloody by the time I was done.

W.

[GAHorn]

If you were to observe how a magneto "fires"... each successive/sequential spark plug receives a "postive" or a "negative" charged spark. This is due to the North/South poles of the magnetic field. Therefore one plug's spark will jump from center electrode to the side electrode...and the next plug in the firing sequence will jump from side electrode to center electrode.
After a period of service each plug's firing electrode will have eroded more than the receiving electrode. By proper rotation of plugs, one can extend the service of plugs. By "polarity" rotation one can more evenly spread the "wear" from the difference.
In addition, many like to rotate their plugs from top to bottom and bottom to top, etc. as lower plugs tend to foul more readily and thereby usually require more aggressive cleaning. By top/bottom rotation, one can more evenly spread the "wear" from the cleaning action.

[N2255D]

Taken from
TELEDYNE CONTINENTAL ® AIRCRAFT ENGINE
SERVICE INFORMATION LETTER SIL 03-2A
GENERAL INFORMATION:
The following Tables number 1, 2, 3 , and 4 list the most commonly used spark plugs by engine model. Additional listings of approved spark plugs may be found in the engine’s FAA Type Certificate Data Sheet and the spark plug manufacturer’s data.
Refer to the spark plug manufacturer’s data for spark plug servicing information and required specialized tools.
Spark plugs must be removed, cleaned, inspected, gapped and position rotated every 100 hours. Refer to Chart 1 for spark plug rotation sequence. Always install a new spark plug gasket when servicing spark plugs or installing new spark plugs.
Chart 2 provides spark plug electrode gap specifications using an alpha code referenced in Table 1, 2 and 3.

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 anit-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.
7. Before installing the spark plug lead connector, wipe it clean using a lint-free cloth moistened with MEK, acetone, wood alcohol or naphtha.
8. Ensure that inside of spark plug barrel is clean and dry.
9. Insert spark plug lead connector into spark plug barrel with fingers in a straight line with the spark plug.
10. Screw connector nut into place until finger tight.
11. Tighten an additional 1/8 turn with the correct size open end wrench while holding the spark plug lead ferrule stationary.
WARNING: DO NOT INSTALL OR USE ANY SPARK PLUG THAT HAS BEEN DROPPED OR HAS ANY MECHANICAL DAMAGE.

Chart 1
SPARK PLUG ROTATION CHARTS
6 CYLINDER ENGINE
SPARK PLUG ROTATION
FROM CYLINDER NUMBER------ TO CYLINDER NUMBER
1 TOP --------------------------- 6 BOTTOM
1 BOTTOM---------------------- 6 TOP
2 TOP--------------------------- 5 BOTTOM
2 BOTTOM --------------------- 5 TOP
3 TOP--------------------------- 4 BOTTOM
3 BOTTOM---------------------- 4 TOP
4 TOP--------------------------- 3 BOTTOM
4 BOTTOM--------------------- 3 TOP
5 TOP-------------------------- 2 BOTTOM
5 BOTTOM -------------------- 2 TOP
6 TOP-------------------------- 1 BOTTOM
6 BOTTOM -------------------- 1 TOP

[HA]

W -

#1 top swap with #6 bottom, #6 top with #1 bottom, 2 to 5, 3 to 4 the same. every time you clean the plugs. they'll all wear more evenly that way.

I see your airplane is for sale, if so then don't pop for fine wires because you won't get the payback from them. those are pretty much "lifetime" plugs in an O300. Unison plugs work just the same as Champions, buy them.

[johneeb]

This is from the end flap of a Champion spark plug box. It appears to be the same as the information posted by N2255D.

I wonder if it makes any difference between engines (0-300's on C-170's) that have their plug wires from one mag go to the top plugs and one mag go to the bottom plugs and engines that have their plug wires from each mag change from top to bottom from side to side?

[W.J.Langholz]

Walt and John
Thanks for the info charts and diagrams.....I like pictures.

HA
Yep the plane is up for sale...I have alot of mixed feelings about that but I can't afford 2 at this time. If my son was a little older and I was a little better off I'd keep it for him.
The massives should last 300-400 hours so and who ever buys it may only fly 30- 50 hours a year so they would last a long time, if it doesn't sell well they should last me 2 years. Either way I want it in top running condition.

Would any of you guys run both kinds ie: if I had 6 good fine wires put them all on the bottom and 6 massives on top? Or am I smokin weed again

W.