Valve Length

[Brad Sjoholm]

Hello All,
I have a 1953 Super A that I picked up with a frozen engine. I pulled apart during the winter. Lots of fun pounding out pistons and sleeves. Since engine was apart and going to replace pistons and cylinders, decided to have the head gone through. I did not pay much attention to the head when taken to the machine shop, but noticed when it was returned one of the exhaust springs appeared to be shorter than the others. I compressed the spring and took out 2 of the exhaust valves, only to find they had 2 differant part numbers. This appears to be from previous work done to this engine. I have looked up both part numbers and they are both listed for use in this Super A 113 engine. I plane to pick up another valve from IH dealer so they will all be the same length, but still wondering
WHY the differance. The length of the shorter valve is 4.83" vs. the rest of the valves at 4.94".

Does anyone have experience with this issue, and does it impact the operation of the engine, with one exhaust valve shorter than all the rest. Any comments or suggestions would be appreciated.
Thank you,
Brad

[John *.?-!.* cub owner]

I wonder if those lengths could be for different heads, such as gasoline only and dual fuel?

[Brad Sjoholm]

John, Thanks for the reply. I will check part number on the head and see if I can come up with a valve specification.

[Jim Becker]

I wonder if those lengths could be for different heads, such as gasoline only and dual fuel?

Yeah, depends on chamber size (compression ratio).

[Matt Kirsch]

According to the limited research I just performed:

The shorter 4-25/32" valves are for engines in Super As with serial numbers below 255418.

Serials 255418-310299 used the longer 4-57/64" valves.

Someone mixed a short valve in there.

As time went on they reduced the size of the combustion chamber in the head, necessitating longer-stemmed valves. The valves on my 240 were 5-15/64" long, as the head had hardly any combustion chamber at all.

[Brad Sjoholm]

Thank you Matt, I appreciate your research. I ordered the longer valve I needed and will be installing the top end this weekend. Have a great Independence Day!