Engine questions A-65 / Champ

[softlanding1]

During my last annual (completed last week), my mechanic pulled #2 cylinder because he thought there might be an issue with leaking lubricant around the spark plugs. This cylinder was a year old, so he wanted the engine shop to look it over. The paint on the cylinder had also turned pink, suggesting that the exhaust gas had been overheated at some point. The engine shop checked things out, found nothing wrong, and cleaned up the cylinder again (new rings, paint, etc). When we went back to install the cylinder, we discovered a strange condition. The valve rocker oil ports did not match the front cylinder on the left side. We checked the rocker arms on the right side, and found the same thing. Per my mechanic, the left valve, being the exhaust valve, needed oil over the top, so the oil port was on the top of that rocker arm. That would imply that all cylinders should have rocker arms with an oil port on the top of the left rocker arm.

Last year, I had to replace the # 2 cylinder because it had issues with compressions (might have been a valve issue). All 4 cylinders show some heat on the exhaust port side, and the engine shop suggested that the engine was running lean. Also, the left exhaust port puts out a dark sooty residue on the cowl, and that has been the case since I bough the plane two years ago. All compressions are great, so I'm not "concerned", but I need to know if anyone has any thoughts on this. The engine was overhauled about 10 years ago, sat for four years, and has about 280 hours since OH. I have flown it over 100 hours since I got the plane two years ago.

bruce marchionda
N84168 - a-65 '46 Champ

[joea]

Bruce,

As I said in my email, have never heard of this on a Continental engine but agree it would be nice to see if any others had this situation or any ideas.

Please let us know what you find out.

Joe

[Paul Agaliotis]

Bruce,
There are actually 3 different style of rocker arms. One has no provision for oil other than self lubrication, this is an Intake. The 2 other have oiling holes for the valve gear. The first has a drilling in the shaft boss under the arm for squirting oil twords the exhaust spring. The last has a drilling all the way to the rocker tip for lubrication. This one has the drive screw to plug the manufacturing hole. All of these can be interchanged but only the exhaust side needs to have added lube holes. If you get them mixed up you will have exhaust valve and spring issues. Refer to the Continental manuals for the proper installation.
Paul

[Roger Anderson]

Hi Paul. Run that past again. Are you saying that in my A65 the intake and exhaust rocker arms are different (I'm certainly not an authority).. I looked in my A65 service manual and in the exploded view it only shows one rocker arm (with a plug screw in the back) and I can't find a mention of a difference to watch for in the installation paragraphs. My A&P shop that installed my cylinders are mostly a big engine outfit. I wonder if they know that and should I pull my rocker arm covers off to take a look? Thanks.

[Paul Agaliotis]

Roger,
The exhaust rocker is drilled for lubrication. Either by a hole at the tip or from the boss. The intakes had no oil to the tip.
Now it has happened in the distant past where two exhaust rockers were installed on each cylinder to provide added lubrication for the valve tips. Works great.
The ratios on the arms are the same and will interchange. I think CMC has a Service Letter on this subject.
Paul

[Roger Anderson]

Thanks Paul. Now that you mention it, when I was cleaning up the parts waiting for the cylinders to be done, I feel pretty sure each rocker arm had the hole in the tip. New rocker arms were installed when it was last overhauled. Great info to watch out for though. I think I'll run it past my A&P just for their info if they don't know that. Thanks a bunch. Roger

[softlanding1]

Paul,

So all the exhaust rocker arms should have the opening at their tip to lubricate the exhaust valve from the top? That's how we ended up doing things, but what a crazy situation. Any ideas on the other items I mentioned? The sooty exhaust out of the left exhaust pipe?

Thanks for the input!

[Paul Agaliotis]

Bruce,
That's an indication that it's running rich. Clogged air filter, primer leaking, carb heat not fully closing many different reasons. If you run car gas it will always be sooty.
Paul

[gusc]

Paul has a good point about mogas causing sooty exhaust pipes. It took me a long time to get used to this because in the old days this meant a rich mixture, often a stuck automatic choke on autos.

[softlanding1]

Paul,

I'll have the mechanic check for leaking primer or carb heat not closing all the way. This is a pickle since the heat indications are that it is running lean (hot exhaust gas). I haven't run mogas in it, so that's probably not it. Thanks for the input everyone. I'll update this if I find anything interesting.