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After a little more than 3 years of flying, and 270 hours, I finally had an issue getting one spark plug out during my annual. It galled the threads in the aluminum head when coming out. Yes, I always use anti-sieze on the plug threads, but that only does so much. So I decided to remove both heads and use Time-Sert Spark Plug Replacement inserts. The kit plus inserts cost me about $200, and the work took me about 3 hours to do all 8 holes. I'll put the heads back on later this week.

1. If you are still building your AeroVee I would recommend doing this upgrade now, instead of later.

2. Heli Coils would not be recommended. I've use Heli Coils for other things, but for the spark plug holes they require removing too much material, and because the existing holes get drilled out, you risk making the holes crooked. The Time-Serts are DIRT SIMPLE and NEARLY FOOL PROOF.

3. The inserts I used were: M12x1.25x17.5mm spark plug insert p/n 42125, from Amazon. But I might recommend the slightly shorter M12x1.25x15mm spark plug insert p/n 42123.

If anyone would like to borrow my Time-Sert kit, please feel free to PM me. No need for everyone to spend $160 for the kit!

I agree, it is worth it to put them in before assembly. It isn't if it is when you will pull out the threads on one of these heads.

The timesert kit is super easy and quick to use as well.

I've used time-serts for a bunch of the aluminum threads on my motorcycles, as well as exhaust stud threads on the aerovee, and am a big fan. Last time I tightened one of the plugs on the Aerovee I didn't like the feeling, so I suspect that one's in my future, too. For spark plugs I wonder about differential thermal expansion and conductivity, though. Those inserts are copper-plated steel, right? It seems they'd really change how much heat is conducted away from the spark plug and make them run hotter. But I guess they're used successfully all the time, so they must work. The threads are probably long enough that there's enough area to not make it an issue.

Be sure to use the ones that are specifically for spark plugs and not general purpose ones. The spark plug serts are made to deal with the heat of the plugs vs the standard serts which are meant for regular bolts.

I too am a fan of Timeserts, and have done the plug holes on my AeroVee prior to first start. I am not sorry!! However, look carefully at the interior after the installation for extra long threads inside the chamber. I used Dremell tool to cut off the longer ones to prevent them from becoming a hot spot ignition source which can lead to damage from pre ignition.

here is a link, "that came up when i searched for time-serts" it is one of the EAA news letters , with a title of
""" EAA News Bits and Pieces Newsletter Spark Plug Hole Thread Repair Using TIME-SERT Inserts''''''
link =
https://www.eaa.org/eaa/eaa-news-and-av ... rt-inserts

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,hopefully this link works..good luck, good day rick

rick9mjn wrote:here is a link, "that came up when i searched for time-serts" it is one of the EAA news letters , with a title of
""" EAA News Bits and Pieces Newsletter Spark Plug Hole Thread Repair Using TIME-SERT Inserts''''''
link =
https://www.eaa.org/eaa/eaa-news-and-av ... rt-inserts

...
..
.
,hopefully this link works..good luck, good day rick

Perfect! That's exactly how it goes.

n502pd wrote:I too am a fan of Timeserts, and have done the plug holes on my AeroVee prior to first start. I am not sorry!! However, look carefully at the interior after the installation for extra long threads inside the chamber. I used Dremell tool to cut off the longer ones to prevent them from becoming a hot spot ignition source which can lead to damage from pre ignition.

I purposely did not grind down anything. If I did then I might have had a "wedge" of insert material that tapered to nothing, and that certainly would be a hot spot. And I didn't want the spark plug threads exposed to the combustion chamber where they would be susceptible to fouling with carbon, making them difficult to remove. This only goes for the plugs on the bottom of the heads, that go in at an angle. The top ones come in straight so no issues there.

All I did was to contour the end of the threadsert to the same contour of the head, wherever the serts protruded. I dont recall if the plugs themselves showed threads beyond the heads or serts. I am sure we are both in good shape anyway!

Please use caution when installing the Time-Serts for spark plug holes. I followed the directions and recommendations in this newsletter write up. I ordered the Time-Sert sizes stated in this article and installed them. Unfortunately, they were too long for my heads. When I tried to remove them, they stripped out the new threads in the heads and the correct size time serts would no longer fit. I then tried the "Big-Serts" but I believe the diameter of the holes required for the Big Serts is too large and will weaken the heads, thus requiring new heads.

Time-Serts cautions not to shorten or grind down the inserts as the lower part of the insert is what flares out slightly to lock the inserts in place.

Jake