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O-300-D, Plugs

2004-06-14 19:45:25

O-300-D, Plugs

Hello Out there,

We have a C-172H with an O-300, D Model in it. ONe mag runs a litlte roough, but clears when we lean it out on the ground. Any suggestions about the type of plugs we should have to keep them from getting fouled up (lead I suspect, but might be a litlte oil too)?

Thanks,

Stan

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2004-06-16 13:08:34

Re: O-300-D, Plugs

I would suggest that you lean the engine aggressively from the time that you start it until you are ready to takeoff.
Glenn

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2004-06-16 19:15:38

Re: O-300-D, Plugs

>We have a C-172H with an O-300, D Model in it. ONe mag runs a >litlte roough, but clears when we lean it out on the ground.

It should always be run very lean on the ground - and in the air as soon as you have finished climb. Otherwise you will soon be adding stuck valves to your problem.
It was never intended to tun on 100LL.

Some pilots buy the Mogas STC and claim that Mogas gets around the problem.

Tony

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2004-06-18 19:03:44

Re: O-300-D, Plugs

Thanks Tony and Glenn,

Yup, that is what I have been doing about the leaning stuff. Has anyone had any experience out there with a fuel additive called ALCOR TCP? I hear that 1 ounce of ALCOR TCP per gallon is about the right mixture to cut down on the Lead problem.

Evidently Iridium tip Fine Wire plugs are better. Would those be Champion RHM38S plugs?

Yes, the Mogas STC thing would work if I could get Mogas at the airports I fly to all the time or carry a hand pump and a a filtering mechanism with me:-)

I will keep leaning it aggressively after start and at cruise altitude I have also been leaning.

It does clear on the ground but not as much as I would like it to clear. It only does it on the left mag and I am pretty sure that the timing on that was set correctly about 25 hours ago when it was swapped out when the other one started to fail.

Thanks again for your inputs,

Stan

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2004-06-19 00:21:16

Re: O-300-D, Plugs

Hi Stan
Alcor TCP is kind of like the Loch Ness Monster of Bigfoot.
Everyone knows about it but nobody has seen it smile

I have been trying to find the stuff for 2 years. Alcor just put you on a waiting list if you call direct. I heard that they had a batch rejected about 3 years ago and since then it hasn't been around.
Having said that, if anyone knows where I can get some - actually get some, not just the promise - please let me know.
I would like to try it.

Thanks

Tony

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2004-06-21 16:37:16

Re: O-300-D, Plugs

Well I guess that slows down the quest for Alcor.

Thanks Again,

Stan

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2004-06-22 05:22:14

Re: O-300-D, Plugs

Stan, The left mag on your engine fires all the lower plugs, while the right mag fires the upper plugs. This is why your mag timing is slightly different between magnetos (28 Deg for left, and 26 Deg for right). And as has been mentioned before the lower plugs tend to lead foul sooner. I recommend cleaning your plugs every 50 hours on the O-300D. Leaning definately helps.

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2004-06-23 13:25:02

Re: O-300-D, Plugs

You might look into the fine wire plugs. They are expensive but are suposed to help. I know one owner that just put them on the bottom to save a few bucks.

Vin

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2004-07-16 16:29:22

Re: O-300-D, Plugs

Stan, I'm having the same problem with my 172G 0-300D on the left mag. I am going to try the Champion REM37BY plugs. My plan is to install them on the bottom and if I really like them then do the top next year. These plugs have an extended electrode and are supposed to be more resistant to fouling then the REM40E and surprisingly they cost the same as the REM40E (about $19). Champion designed these to address the problem with lead fouling using 100LL. The Iridium fine wire plugs would be a better choice but at about $60 a piece I'm going with the REM37BY first. The REM37BY are approved for use in the 0-300D.
Here is a link to a new bulliten from Champion on the 37BY plugs;
http://www.championaerospace.com/news8.html
And here is a link to an article on Sacramento Sky Ranch web site (great place) on preventing lead fouling with a pic of the 37BY plug;
http://www.sacskyranch.com/faq_spark_plug/FAQ00007.html