Valve questions

I was running my TO20 the other day to burn a little old gas out. IT started right away and was running fine. When it quit running I put fresh gas in and it did not want to start, acted like it wanted to back fire. It did start but was running rough for a while then cleared out. I thought something might have been blocking the fuel flow and it cleared itself out.

I went to start it the next day and I had the same problems starting. I pulled the valve cover and took off the rocker arm and noticed several bent push rods. The rocker arm had been plugged in two of the center oiling ports.

I pulled the head and several valves were almost stuck and had to be tapped out with a hammer. They looked like the oil had been baked on them when looking at them from piston side.

Question 1. With the oil ports clogged I can understand the heat to bake on the oil but would there be enough oil for it to bake on them?

Question 2. After researching valve kits they all seem to come with pin type connectors. Are they safe and if I get them is there any other parts I should get like end caps, different type of stem guards etc.

Question 3. what about oil seals on the valves, I am not sure mine had them. What do they look like?

Thanks in advance

Jim

I think your first hunch was right. The sediment bowls tend to- not vapor lock, but trap an air bubble or plug up often, have a two stage needle valve etc. If it ran OK earlier, I wouldn't mess with the valves, but sounds like you already did...

Bent push rods are common on engines that thave sat unused for long period of time. The oil and combustion products combine to make a sticky mess that sticks the valves in the valve guides and the cam forces trying to lift a stuck valve will cause the pushrod to buckle. This is independent of poor oiling of the rocker arms and valve stems.

When I re-did the head on my TO-30 I had several bent push rods and luckily I was able to find some straight, used ones. The push rods can be straightened by tapping them carefully with a hammer on a flat surface and any remaining deflection in the push rod "adjusted out "but it"s best to replace them with straight ones if you can.

Thanks for the info. I have two TO20s, one for over 50 years, and this has never happened before.

I purchased some push rods off of ebay. Lets hope they are straight!

It sounds very similar to radial aircraft engines. They need the props turned through several times before engine start to get rid of oil build up on the lower cylinders.


Jim