CHT's newly overhauled engine 0-200

[6597]

Is there a rule of thumb as to when I can start seeing CHT's drop some after an overhaul?

Currently ambient temps in the 60's, climb out CHT's 400+, drops to 375 after about 10 minutes cruise, and after about 20-30 minutes I'm down to 345-350. Oil temps a steady 180.

14 hours on the tach at the moment, burned about a quart and a half so far (steel Millenium cylinders).

Aeroshell 80 (40wt) straight mineral. We'll go to straight weight Aeroshell W100 at 25 hours.

I did do an initial oil change at 2 hours, boy that stuff looked pretty awful....

Traditionally pre-overhaul I had a hard time keeping the engine warm, CHT's in cruise were usually 275 or less.

[TheFlyingMechanic]

What was your power settings? We normally have 25 hours on a new overhaul easy... 3-5 on just a cylinder...

I know that this is Lycoming but it might help give you some answers...

https://www.lycoming.com/sites/default/ ... mption.pdf

[6597]

I usually run between 2200 and 2450 in cruise for now, normally 2450.

I've checked the baffles a dozen times, they are old but tight (I'm currently patterning new ones).

It just may be a combination of new cylinders, overhauled carb and overhauled mags that are contributing and making the previous old tired engine look it's age.

I know my static rpm jumped from about 2300 pre-overhaul to 2450, I had to adjust the linkage to drop it back a little. Hate leaving power on the table, maybe a re-pitch will be in the future.

16.5 on the tach now, the oil consumption is definitely settling down now.

We'll see where the temps are when the tach hits 25.

[6643]

I had to adjust the linkage to drop it back a little.

I don't understand what you're saying, unless you mean you limited the throttle to less than full open, in which case, well. static RPM is measured at full throttle...

When was the last time your tach was checked?

[6597]

John,

Yes, I limited my throttle 'throw' by adjusting the connection, you are absolutely correct. I don't like it but other than re-pitching the prop it's the only option I have in the short term. Regardless, I think my 'new' engine has more ponies than the old one.

NewThrottleLinkage.jpg (48.25 KiB) Viewed 1291 times

As far as checking the tach my ancient HeathKit analog handheld tach says all is correct, however my A&P friend has a more modern unit that I will check with.

s-l640.jpg (26.97 KiB) Viewed 1291 times

Here is the 337 response I have from Witchita regarding the particular prop I have, it's a 71/42 on the 0-200. My best guess is when an ancient owner decided to re-engine to the 0-200 he didn't want to shell out money for a new prop on the STC so he 337'd the McCauley he had. I can't complain on the performance but I do need to watch the overspeed when transitioning to cruise. The plane climbs like a rocket, 1100-1200fpm with me and full fuel at sea level where I'm at. Cruise is still at 2450-ish and 105mph indicated so I don't think I gave up much at all in cruise.

img220.jpg (122.43 KiB) Viewed 1291 times

I think Randy has done his homework extremely well and his prop requirements and advice would be much more appropriate for the 0-200. This just happens to be what I've inherited and I've learned to live and work with it.