National Aeronca Association Bulletin Board

I am new to flying with the A-65. I was discussing with a friend about flying with the engine at lower RPM settings. He stated that the 65 needs to be ran at full cruise RPM which is better on the engine. I wanted to get some other feedback on this.

Thanks,

Todd Wilemon

Hey Todd,

I cruised all day at 2200rpm on my A-65; that's where it was happy. If I wanted to loiter around quietly, the engine was just as happy at 1800rpm. It's only quirk was high oil temp: if it got above 215' valves would start sticking. I'd run your engine where it is smooth; be it 2100rpm or 2300rpm.

The hardest thing on an airplane engine is change. Jocking the throttle all day long doing pattern work is harder on it than a high cruise setting.

nkh

I tend to run my A65 at around 2150 where it's the smoothest, burns about 4 gallons per hour and I show around 85 mph hour, give or take a little. The A65's are pretty tough little engines probably due to the low compression ratios and low firing pressures.

Mike Berg

I appreciate your input guys.

Thanks,

Todd

Check out the TCM tech info site. There is a great booklet about engines that Continental hands out with new or overhauled engines.

What we have here are 1940's engines, a long way away from modern stuff and we have to consider how engines operated and how they were designed then.

The engines were always designed to work hard, that is why they have a high capacity for a low horsepower. The peak horsepower is generated at a low rpm, hence you have a lot of pressure on the pistons.

No problem, they are designed to take it, however, the integrity of the engine and the oil seals around the piston require a good seat between the rings and the cylinders.

If you loiter around and baby your engine, the blowby and products of combustion can get past your piston rings, carbonise with oil residue and glaze the bores - bingo, high oil consumption, low compression, mechanic gets a payday !

I'm not saying run it flat out all the time - just give it a workout regularly, a nice fast cruise at some point regularly, above all, regular - and I mean 10 hours regular oil changes on a non filtered A-65 will ensure a long, healthy and happy engine life.

For an A-65, don't spend the extra on multigrade - a good single weight, say 80 in winter, 100 in summer depending on your location will be fine - after all it is better than the stuff they put in it when it was new !!

Oh, and don't forget a splash of MMO in the fuel. It isn't snake oil, it is upper cylinder lubricant and keeps the valves sweet and stops them sticking. Look back in the old adverts or for those of us of a more - er - mature standing, we remember our Pop always putting Redex or similar in with the fuel to keep the auto engine sweet. Well that was in them old days when our engines were new

p.s. - maybe a Brit but I try speak American !

Mike

I fly at least 5 hours a week using Phillips 66 x/c 20w50. I have been changing oil ever 25 hours. Every 10 hours seems like to much to me but, I don't know much.

If the dicussion groups consensus is 10 hours I'll get more oil and start chainging it twice a month.

25hrs is perfect.

nkh

Nathan,
Are you recommending changing oil at 25 hour intervals even when you have a spin on oil filter? I had thought that the filter addition would double the interval to every 50 hours? At 25 hours, the new engine we have doesn't even dirty the oil, its still very hard to see on the dipstick.....

Comments?

Mike

On my personal airplanes yes; 25 hrs even with a filter, but if it stretches to 30, it's no big deal. My thinking is; oil is cheap and i want it as clean as possible. Plus, it's the best insurance you can buy for an airplane/motor.
For customer airplanes, I'll use discretion and change it at 50hrs per request, but no longer.

To show you how paranoid I am about engine oil, here's how I broke in my motor:
0.2hrs on the tach - oil change (first run, on the ground.)
1.0 oil change (second ground run and first flight)
5.0 oil change
12.0 oil change
25.0 oil change
50.0 oil change

If you change it often enough, the oil will never look dirty.

nkh

I use 20W50 (Phillips) and change somewhere between 18-22 hours. No filter just a screen. Usually the oil is getting dark by then. When I had my Cherokee 140 with a filter I changed somewhere between 20-25 hours. I probably only fly 30-50 hours per year so the intervals get shorter at times as I tend to not want to let the old oil set in the crankcase for more than 4 months regardless of the hours.

Mike Berg

I think Nathan is right on with a new engine. I remember getting a yellow tag crankcase from Divco that was pretty as a picture. It had a tag attached which said something like, crankcase not cleaned of chips. Don't remember the exact wording but something like that. The thing was clean enough you could eat off it but I did as the tag said and flushed the oil galleries. DAMN, I got about two table spoons of chips out of the galleries.

How good did I flush it? Did I inject any new chips or debres for assembly? So I also changed oil after first start up and then after two hours of flight and so on. Plus I got oil analysis done.

It sure got my attention! I still can't get over the amount of chips I got out of that engine when it was so prestine looking.

Dennis

Thanks for all the input guys. Very helpful info.

Todd