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While I had my engine out, I thought I would pull the heads to recheck my compression ratio. Good news is that it is set correctly for 8-1. Problem is that Sonex recommends I change the copper head gaskets. How do you get the old ones out without damaging the aluminum head? Is it really critical that they be replaced? Only 100 hrs on engine.

Oil analysis came back clean so no excessive wear caused by out of tolerance end play on crank.

I was surprised by the amount of lead deposits I found inside the heads and on piston domes. Cylinders looked good.
Anybody have any experience with this?

Glenn Hunt Sonex N414SX

Glenn.hunt wrote:I was surprised by the amount of lead deposits I found inside the heads and on piston domes. Cylinders looked good.
Anybody have any experience with this?

Glenn Hunt Sonex N414SX

Are you using the Sonex-suggested lead scavenging additive?

Mike

Never heard of it.

Another way to keep lead fowling to a minimum is leaning. This is especially true on the ground while taxiing. There's no reason to be at full rich while the engine is basically idling. also, when flying at cruise power, go ahead and lean it out. Just watch the EGT and CHT to make sure nothing gets out of whack. You won't hurt a normally aspirated engine by leaning it once you're at cruise power settings or below, but you will help keep the plugs and valves clean by keeping the temperatures up. Too cool isn't cool when it comes to engine temps, especially when using leaded fuel.

I too notice that after a long cross country trip where I was required to use Avgas that a lot of lead buildup occurred. I lean very aggressively on the ground and air with an average fuel burn in the air of less than 3.5GPH. It looked almost impossible to get the head gaskets out. I was able to get them out really pretty easy with using a single edge razor and gently working it under the gasket around and around till it loosened. I have always replaced the copper gaskets each time I have had to remove the heads. But I know what you mean, they are a little expensive. I use to use TCP in my Maule and it worked great as a lead scavenger.

I always lean aggressively, in air and on the ground.

Joe Norris, I was going to email @ tech support but seeing you are online here, how would you suggest getting the copper head gaskets off.

GW, thanks for the razor idea, I will try that while I wait for Joe's reply.

Also, my plugs are always clean when I pull them.

Glenn.hunt wrote:Never heard of it.

In the AeroVee manual it recommends a TCP fuel additive. I bought a quart from ACS, P/N 05-21300. There is a dispensing syringe that you get for it as well, as it only goes in in small quantities (1 oz per 10 gal of 100LL).

Mike

Glenn,

I've never had any trouble getting head gaskets out of the heads. Just a thin blade or a pick to get under the gasket a little bit and it should pop right out.

TCP is a wonderful thing, if you can find it. It seems like the supply is a bit "off and on", so when you find some you should buy it. Good stuff for use in all engines that are burning leaded fuel but really don't need the lead.

Mike, can you elaborate on where you found the TCP recommendation in the Aerovee manual.

Ken W