100 octane exhaust valves

[KatieB]

During the course of my O-320-A2B's top overhaul and conversion to 160 hp (Experimental B2B) by Aero Sport Power back in 2006, they installed "100 octane exhaust valves." No specific part number is in the log book entry. Does anyone know what this means? Could they be the Inconel exhaust valves I read about in the overhaul manual?

 

[Boyd Birchler]

100 octane valves

The reference is most likely because the 150 HP version was a 80/87 octane engine and the 160 HP engine requires I believe 96 octane (which is no longer made) that now defaults to mean 100 Octane required. Lycoming must have up graded the valve metallurgy for the 160 HP version of the engine. These valves should be acceptable with 100LL or premium auto (if occasionally given a batch of leaded fuel) should you so desire.

The log entry means they did not short cut the need to upgrade the valves.

 

[KatieB]

I guess what I should have asked is, how do you tell what kind of exhaust valves you have? I haven't taken them out yet. Is there a part number on them somewhere? The overhaul manual says exhaust valves should never be reused after overhaul unless they are Inconel valves. Mine have less than 500 hours, so unless they are damaged, they should be ok, but I'd like to know what kind they are.

 

[az_gila]

I guess what I should have asked is, how do you tell what kind of exhaust valves you have? I haven't taken them out yet. Is there a part number on them somewhere? The overhaul manual says exhaust valves should never be reused after overhaul unless they are Inconel valves. Mine have less than 500 hours, so unless they are damaged, they should be ok, but I'd like to know what kind they are.

According to this Lycoming 2014 SI, all of the O-320 exhaust valves are "1/2 inch diameter chrome plated sodium cooled stem exhaust valve".

http://www.lycoming.com/Portals/0/t...I_1037_P_Approved_Pistons_Rings_Cylinders.pdf

None are Inconel valves....

 

[KatieB]

Thats interesting... I can't find an Inconel exhaust valve on the chart either!

 

[aerhed]

They won't be inconel. If they inspect really nice at 500 hours on my own experimental, I would regrind and reuse. Use the six hundred bucks elsewhere. Ex valve reuse is ok per lycoming except when overhauling I/A/W the mandatory replacement list. That's only required to claim a certified engine is "rebuilt" or "overhauled to new limits". If they don't inspect like new I'd go with Superior exhaust valves.