Lycoming cam inspection question

[jcarne]

Okay I went down another rabbit hole into the late hours of the night on understanding Lycoming engines. I understand that there really isn't a good way to inspect a cam on one with flat tappets. However, theoretically if the engine has roller tappets couldn't they be pulled to have access to inspect cam lobes? Am I missing something?

I am in no way asking because I plan on doing this to my new engine, I am just trying to understand Lycomings a bit better and need to call in those with more knowledge. Thanks!

[vic syracuse]

No, you need to pull a cylinder to see the cam.

Vic

[DanH]

Lycoming, no, as Vic says. Some Superior engines with roller tappets, yes, but the whole point of roller tappets is to not eat cam lobes.

[rocketbob]

On the 540 you can look at the middle cam lobes thru the dipstick hole.

[jcarne]

Originally Posted by DanH

Lycoming, no, as Vic says. Some Superior engines with roller tappets, yes, but the whole point of roller tappets is to not eat cam lobes.

I understand the point of roller tappets but why do you say only some superior engines? It's my understanding that even a Lycoming factory engine like an M1B could have the roller tappets pulled without taking the case apart. Is that not true? If the tappets are out I would think that would expose the cam lobe the roller rides on. Am I missing something?

[Jim Ball]

Lycoming(R) and Titan roller lifters are interchangeable but cannot be removed without splitting the crankcase. This is due to the way that they are anchored from rotating in the case. SAP rollers are designed differently and can be removed without complete disassembly. There would be very little reason for doing so, though. The cam lobes do not wear down due to rust or contamination. Spalling is not an issue with roller lifters.

[jcarne]

Originally Posted by Jim Ball

Lycoming(R) and Titan roller lifters are interchangeable but cannot be removed without splitting the crankcase. This is due to the way that they are anchored from rotating in the case. SAP rollers are designed differently and can be removed without complete disassembly. There would be very little reason for doing so, though. The cam lobes do not wear down due to rust or contamination. Spalling is not an issue with roller lifters.

Thanks for the reply Jim, now I understand! I wasn't aware that the Lycoming rollers couldn't be removed.

Understood on why rollers are used. Definitely a requirement when I bought my engine. (queue all the roller haters now...)

[Marc Bourget]

Supplement to "have to pull a cylinder"

If you're careful you might be able to un-nut a cylinder and pull it away from the case without removing the piston from the cylinder - take your "peek" at the cam and reassemble.

Saves a hone and new rings, etc.

FWIW

[PCHunt]

Originally Posted by Marc Bourget

Supplement to "have to pull a cylinder"

If you're careful you might be able to un-nut a cylinder and pull it away from the case without removing the piston from the cylinder - take your "peek" at the cam and reassemble.

Saves a hone and new rings, etc.

FWIW

Or, remove the wrist pin, and take the cylinder and piston off as a unit, no honing needed when replacing. A new cylinder base O-ring would be a good idea.

[DeeCee 57]

supplement to supplement

Before doing such work, Mike Bush offers some excellent advice here https://m.youtube.com/watch?v=I4tzOAaNfyQ

Also of note, to inspect all lobes of said camshaft, you would need to pull a second cylinder, for instance 1 & 4, or 3 & 2...