Titan 0-340 Burnt Intake Valves

[lr172]

Pics from O/P. Definitely looks like burnt intake valves. I speculated they started from a small angle error when the guide was reamed or possibly setup error when the valve face or seat face was ground. The slight leakage at the contact area would allow the flame to propagate just a bit past the seat into the intake chamber. Over time, that clearance would grow, from flame activity, to the point of allowing greater and greater heat retention in the valve at that area and the burning seen.

Larry

[RV6_flyer]

Originally Posted by Mike Macon

Thanks Gary. I know you were not a big CA fan but are you missing the left coast at all?

I miss my friends, I miss the scenery, and I miss the climate. I do not miss the congestion, I do not miss the high cost of living, I do not miss the regulations, and I do not miss the politics. More bad than good.

I have flown there commercially twice last year and once this year. Almost everything I saw as 140 to 150% more than what I pay here in North Carolina.

[FORANE]

Originally Posted by Mike Macon

Also curious if anyone else makes replacement cylinders besides Titan for this engine.

As a new Titan x-340 owner I too would like to know this for future reference.

Originally Posted by RV6_flyer

I am not aware of anyone making cylinders for the 340 other than Titan.

As I understand it, the 320, 340, 360 all use the same head, head parts, and bore but have a different stroke. The different stroke requires a different crankshaft, connecting rod, and cylinder barrel.

So o-320 cylinders wouldn't fit?

Can anyone confirm this?

[BillL]

Originally Posted by Mike Macon

Gary - This is my second one. #1 cylinder at 600 hrs. and now #4 at 650 hrs. There is a definite burn mark at the valve head edge. I used to be a little better at posting pictures to this site and I will work on that. CubCrafters replaced the first cylinder after me and a mechanic gave up chasing what we thought was an ignition issue because it only missed on one ignition. Ran fine on the other. They had never seen a burnt intake valve before mine. They chased the ignition for awhile also.
I have only found one similar burnt valve issue with the 0-340 on the internet and his picture was identical to mine. I was just curious if there were any more similar issues out there or am just I just the only unlucky dude. Also curious if anyone else makes replacement cylinders besides Titan for this engine.

I would bet on either poor sealing from the beginning (bad seat geometry), or push rod length or basically lash setting. I would expect that ignition would yield other issues long before it would burn an intake valve.

Now, this is assuming that the valve was new, and had a proper thickness from the beginning. A thin edged valve can still burn even with proper lash and seat contact area.

The fact that all cylinders are doing the same thing indicates it was built improperly and consistently in some way. It could even be poor metallurgy of the valve heads, but that would be low on the list of potential causes. Replacement of all intake valves would be required.

[RV6_flyer]

Originally Posted by FORANE

As a new Titan x-340 owner I too would like to know this for future reference.


So o-320 cylinders wouldn't fit?

Can anyone confirm this?

The Titan replacement document uses different part numbers for 320 and 340 plus shows different stroke on the cylinder wall.

[rocketbob]

Intake valves not rotating suggest tight guides and/or rocker geometry not spinning valve.

[Full Throttle]

What rotates the valves in a Lycoming engine?

[rzbill]

Originally Posted by Full Throttle

What rotates the valves in a Lycoming engine?

The rocker contact point is not centered on the valve stem by design.

[lr172]

Originally Posted by rzbill

The rocker contact point is not centered on the valve stem by design.

I kinda question if lyc got that geometry right in the early design. Why else would they have added the rotator cap to the exh valve, if the geometry was set up properly to drive rotation. I assumed the offsets were built into that cap and not the rocker geometry. Why else put it there, where it forces the use of those compromised keepers.

Larry

[Full Throttle]

Originally Posted by rzbill

The rocker contact point is not centered on the valve stem by design.

So if one was to use roller rockers on a Lycoming engine, all the valves would have a good chance of burning. Is that correct?