I've got lead balls

s_tones · #1 02-23-2009, 05:57 PM

I pull my plugs and clean them at every oil change (typically about 35-40hrs).
Of course there are always lead balls, particularly in the lower spark plugs.
(I lean aggressively on the ground and 75-100 ROP in the air.)
I also fairly commonly see material lodged in the spark plug gaps of the lower plugs. I assume this is lead as well. The last time I cleaned them I believe there were at least 4 bridges formed in the lower plugs. These are REM37BY plugs so if one gap is bridged, the other may not be.
What is surprising to me is that the engine runs perfectly normally with normal RPM drops during mag checks despite this finding.

Do you think these plugs fire normally with these deposits on them?

Do you guys see this accumulation?

Steve

David Clifford · #2 02-23-2009, 06:10 PM

Those are the same plugs I am using in my O-235 and are supposed to be the best choice against lead fouling according to Lycoming. I replaced the old ones with brand new ones about 125 hours ago and I see no difference in engine performance or time before build-up than with the old plugs. I pull and clean the plugs every 35 hours or so and the bottom plugs are always full of lead,,,,just like the old ones. Scared me the first time I pulled a bottom plug,,,,I thought the piston was melting and filling in the electrode gap with melted piston dome!

s_tones · #3 02-23-2009, 06:32 PM

I had the same experience the first time I pulled the lower plugs.
Little green balls rolled out!
I am still perplexed however as to how the plugs can be firing, apparently normally, with obvious lead deposits in the gap.

Steve

Mel · #4 02-23-2009, 06:35 PM

Try running TCP. It softens the lead and lets most of it pass out the exhaust. It won't get it all, but it helps. I have one particular customer who doesn't run it and his lower plugs are almost shorted every year at condition inspection time.
There's also Decalin. It does the same thing.

JonJay · #5 02-23-2009, 06:46 PM

that does not sound very good though. I just completed my conditional this weekend 75 hours since last plug inspection. I was surprised how clean all the plugs where with no difference between top and bottom and only very tiny amounts of lead depost, I mean specks, no balls.
I wonder if quality of fuel or brand might have something to do with it? I run my IO360 LOP some, but not obsessively? My engine is also 165 hours news, maybe that too?

mannanj · #6 02-23-2009, 07:04 PM

For some reason, O-235's are particularly plagued with lead fouling. Mel's advice on TCP is spot on.

TCP really helped on my 65hp. Aeronca Champ. When they quit making 80 octane I had to use 100LL or auto fuel (which I hated).

The 65 Continental was designed for a minimum of 67 octane fuel. 100LL has at least 4 times the amount of lead that 80 oct. had.

Years ago, TCP used to be provided in the blend of auto fuel that boasted the "ethyl" Logo. (TEL; or Tetra Ethyl Lead.)

Get some TCP, use it regularly and I think you will be pleased with the results. In fact anyone with a compression ratio of less than around 8.5:1 could probably benefit from using it.

IowaRV9Dreamer · #7 02-23-2009, 07:13 PM

The Skipper has lead balls, too. Many of the low compression engines foul badly on the high lead concentrations in 100 "Low Lead". Cessna 150s are known for this behaviour also.

The Lycoming Flyer states that one way to help is to idle at 1200 rpm, to keep the plugs / cylinders hot enough to activate the lead scavenging additive in the fuel.

I have about 70 hours on the Skipper plugs now (the REM plugs listed above on the top, fine wires on the bottom due to oil). So far still no problem on the mag check, but every mag drop is proceeded by a short 2000 rpm "lean off" event. This seems to help, along with incredibly aggressive ground leaning.

I'm hoping they do something like a 95UL aviation fuel that us low compression guys can use.

RScott · #8 02-23-2009, 09:45 PM

FWIW, if you fly a certificated aircraft while working on your RV, Decalin is now approved for certificated aircraft. Not as hazardous as TCP and it can be carried safely in the aircraft. ACS sells it; I don't know who else does.

David-aviator · #9 02-24-2009, 05:57 AM

Quote:

Originally Posted by RScott

FWIW, if you fly a certificated aircraft while working on your RV, Decalin is now approved for certificated aircraft. Not as hazardous as TCP and it can be carried safely in the aircraft. ACS sells it; I don't know who else does.

You can buy it direct from the guy who invented it, Chris Lowery. He is a very smart chemical engineer.

http://www.decalinchemicals.com/

Chris is a successful Subby aviator.

My take on the lead balls is it is caused by running too rich.

Remember the 0235-L2C in the Tomahawk and C-152 in a training environment, they had to have the plugs cleaned every 50 hours. I had the same engine on a Long EZ and its plugs would go from one annual to another with almost no lead build up whatever. The difference was operating technique. The trainers flew around all day at full rich. The only time my engine was at full rich was on take off and on a hot summer day it was leaned slightly on the roll. After take off, it was throttle back just bit to get it below 75% and mixture back to get a good rise on EGT. I do the same with the 0360. There is very little lead fowling. And the REM37BY's do help.

David Clifford · #10 02-24-2009, 07:10 AM

I never heard of TCP before this post so did a Google search and came up with a comparison with that of Marvel Mystery Oil. http://www.pipercubforum.com/marvel.htm Anyone try using this? Readily available just about everywhere and inexpensive.