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[EMAIL PROTECTED] wrote:
What plugs are in the engine and what fuel are you burning? Continental and Champion both list several different plugs available for the C 85 engine. Check the web sites to see what is recommended. You also may need a plug with a different temperature range to prevent fouling. Several alternatives are available depending on how the plugs are fouling.
If you are burning pure 100 LL you could be getting lead fouling. If you are using mogas, make sure its fresh, non-contaminated, and free of alcohol. Also to consider is any additives that have been or are being used. My experience is that they are seldom needed and sometimes do more harm than good.
Once you get it solved, be sure to post the answer so that all Coupers can learn from it.
Good luck,
John Roach
N 2427H
Don,----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----Anyone:We have a 415 C with a 75 Continental upgraded to a C-85 and with a Stromberg Carb. The engine has about 300 hours on it since major overhaul and about 150 hours since a top overhaul. It was brought back into service about 18 months ago after sitting idle for about three years.After a carb problem, which was fixed by replacing the needle valve, we have flown the plane about 60 hours in the last 18 months. In the last month or so we have had a rough mag check on the left mag and our A&P checked everything over and found nothing wrong with the ignition system. i.e. mags, wriing, plugs etc. As a last resort he switched the plugs from the top cylinders to the bottom and the problem went from the left mag to the right mag. He concluded that it was a plug problem and suggested that we pull all of the plugs and have them cleaned and gapped. This we did and the problem went away for awhile.After the plane sat idle for several days it started easily but the problem occured again but now ot was the right mag. Out of desperation and because we don't have a mixture control to lean out the engine to clear out the problem we ran it up to about 1,800 on only the bad mag and the problem went away. Now we had a good mag check. Problem solved - no! A few days later we tried to fly again and the same problem came back. This time we didn't have time to run it and try to burn out the fouled plug.Because we had some oil on the bad plugs we had our A&P do a compression check to see it there was any blow-by that was fouling the lower plugs. The compression check found every cylinder in the high 70s over 80 which was good news.Does anyone have any ideas about how ot solve this problem. We would like to hear from anyone who might have some suggestions.Thanks for your help.DonN93334==============================================================================
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What plugs are in the engine and what fuel are you burning? Continental and Champion both list several different plugs available for the C 85 engine. Check the web sites to see what is recommended. You also may need a plug with a different temperature range to prevent fouling. Several alternatives are available depending on how the plugs are fouling.
If you are burning pure 100 LL you could be getting lead fouling. If you are using mogas, make sure its fresh, non-contaminated, and free of alcohol. Also to consider is any additives that have been or are being used. My experience is that they are seldom needed and sometimes do more harm than good.
Once you get it solved, be sure to post the answer so that all Coupers can learn from it.
Good luck,
John Roach
N 2427H
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