Van's Air Force
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Spark plug life
- Thread starter Cadstat
- Start date
Keep them gaped and cleaned regularly and test each one with an ohm meter whenever you remove one. Any that read above 5000 ohms, throw it out. Also if you ever drop one while handling it on a cement floor, pick it up at once and drop it again on purpose,,,,then throw it out. You should get engine TBO if cared for properly.
The are good a lot longer that that.
Get a Go / No Go gauge and let that be your guide other than time in service as to good or not.
All the other good or not good factors still apply but if they pass the Go / No Go Gauge, I would keep using them and have for more than 1,000 hours.
Get a Go / No Go gauge and let that be your guide other than time in service as to good or not.
Last edited:
Greg Arehart
Well Known Member
Gary,
What's the hole diameter? That tool seems like something fairly easy to make unless the hole is some funky size.
greg
What's the hole diameter? That tool seems like something fairly easy to make unless the hole is some funky size.
greg
Yes. One ohm lead probe needs to touch the metal contact inside the barrel of the plug where the harness contacts and the other lead to the center electrode. You may have to modify the probes plastic insulator to fit inside the plugs barrel. This is just a basic test to help weed out a definite bad plug.
I have not measured the hole size. It also has a tapper (countersink) to it. Typically if you stop by the Champion booth at an air show, they will give you a gauge FREE.
Neal@F14
Well Known Member
Aviation spark plugs very well can be resistor plugs. In fact, most of them are resistor type. The "R" in the part number means resistor. See http://www.aircraftspruce.com/catalog/eppages/champsprkplugs.php for details.
The nearly brand new UREM-37BY plugs in my Cherokee measure about 1000 ohms from the wire connector to the tip electrode.
The nearly brand new UREM-37BY plugs in my Cherokee measure about 1000 ohms from the wire connector to the tip electrode.
Neal, just because I never saw one with a resistor I assumed they were all like that, the more modern technology is the key word, thanks for getting me straight, Mike
Inside the insulator and inline with the electrode is a resistor. This resistor serves to limit the peak electrical discharge current when the plug fires, thereby reducing electrode wear. The resistor of the plug can be manufactured in a number of different ways: either as a multi-part assembly or in a monolithic fashion ? "doped" into the glass seal. The monolithic resistor is a more modern technology and offers improved reliability, longer life, and is more economical to manufacture.
Inside the insulator and inline with the electrode is a resistor. This resistor serves to limit the peak electrical discharge current when the plug fires, thereby reducing electrode wear. The resistor of the plug can be manufactured in a number of different ways: either as a multi-part assembly or in a monolithic fashion ? "doped" into the glass seal. The monolithic resistor is a more modern technology and offers improved reliability, longer life, and is more economical to manufacture.
Greg, The hole size is .26
The wear happens between the center and the inside of each side post. So when you gap the plug, you are pushing the side post toward the center post. When the measurement O.D. of the posts is less than .26 then the plug is considered junk.
The hole gauge is just an easy way to check if the plug fits in the hole it is no good. The taper on the hole of the gauge is there to make it easier to see if it went inside. You could just measure the O.D. of the posts with a caliper. You are measuring just the tip because it is tapered due to the adjustments of the gap over time.
Lead balls in bottom spark plugs
Inspected spark plugs today on Lycoming O-320, previously swapped plugs from bottom to top at 50 hours. Now at 100 hours inspected again. All four bottom plugs have lead balls deep inside. Cleaned, reinstalled, didn't notice any changes in engine performance.
Inspected spark plugs today on Lycoming O-320, previously swapped plugs from bottom to top at 50 hours. Now at 100 hours inspected again. All four bottom plugs have lead balls deep inside. Cleaned, reinstalled, didn't notice any changes in engine performance.
Sam Buchanan
been here awhile
Yep, that's what happens with 100LL. Leaning aggressively on the ground will help but you can expect to see lead balls in the bottom plugs. You handled the situation properly.
RV10inOz
Well Known Member
Vlad
Looks perfect except I would check the gaps with a wire plug gap gauge.
16-18 though is where to set them and any over 22 will not be performing at their peak. There is a go no go set, at 15 and 19 though I think on them.
Aircraft spruce sell all the bits you need.
Looks perfect except I would check the gaps with a wire plug gap gauge.
16-18 though is where to set them and any over 22 will not be performing at their peak. There is a go no go set, at 15 and 19 though I think on them.
Aircraft spruce sell all the bits you need.
