Interesting Valves

[Harold R]

After many distraction over the past few months, I decided it was time to jump back to the cub fixin mode and tear into the '69 FCUB fog machine. This was a great running....very straight cub with no problems except the smoke. I say its a '69....engine sn is 268xxx, with P casting codes. (Tag missing off bolster). I had used the tractor the past few years sparingly, only running a seeder used to spread fertilizer, but I didn't care for the smoke....so it now sits in pieces in my shop. The one interesting thing so far has been the engine valves. They are...I think....not original, even though it was my belief that the motor had never been into. I can't find any info on them, but the manufactorer certainly made a lot of automotive parts. They are in good shape and will go back in as soon as my other parts come in. The intake valves are concave on top but not centered, and the stems are cut down from 5/16 ths to about 7/32nds in the area where they are exposed in the intake. I suppose for better flow. Here are some pictures.......anyone else have these valves?

Standard intake valve on the left.

[ScottyD'sdad]

I've done a lot of valves. Never saw any like those!
Ed

[raystractors]

I had two of those in one of my cubs, but thought that someone was just using what they had. I broke one when I was freeing up some stuck valves, and replaced them with some that were stock. It does look like they would give more room for the intake gases.

[tst]

They are replacements, have seen several of them

[Gary Dotson]

I've never run into them on a Cub but have seen them on a lot of other applications. Yes, the cut down stem is supposed to improve port flow.

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

It has been a long time since I worked in an automotive parts place, but as I recall those valves were for building hot rods. The reduced stem both reduced the weight of the valve, and allowed increased air/fuel mix flow. The exhaust valve depression both reduced weight, and exposed more surface to allow faster cooling as the fresh charge came in. The stem of the exhaust may have also been sodium filled to carry the heat away from the head and dissipate it down the stem. All of those were good if building a 500+ horsepower, 8000 to 10000 rpm hot rod or drag racer, but kind of expensive for a 10hp 1800 rpm cub.

[Dave F.]

I've used the step down valves in my 48 cub, I belived they came from Tisco. At the time I thought they were strange also, But George Willer at the time said they were ok. So far no problems with them been going on 14 years Dave F.