I bought a '42 SnoGo last fall (with a newer flathead in it, an 8RT) that had sat unused for some time, at least fifteen years.
Well, you just can't do that here in Alaska and hope to get away with it. With 150°F temperature swings between seasons, there's too much condensation. Plus, the engine had been poorly maintained when it was in use—the oil filter was so full of sludge I was able to scoop it out and bake cupcakes with it.
So it's little surprise that about half the valves were stuck.
Here's where I'm at so far on the project: https://youtu.be/sY185uY7vu8. (Was going to wrap it up for the winter, but changed my mind.)
I've got 'em all freed up except #s 5, 6 and 7 exhaust. They're still stuck in the guides and the guides are sliding freely up and down in the block. The retainer clips slide right out.
And that's where I sit.
If they were on the intake side I could soak 'em in solvent and be done with it. But they're on the exhaust side, which means that anything I put in there drains right down through the block into the manifolds.
I'm headed back over there again Thursday, when I hope to borrow a friend's pickle bar and see if I can somehow pry 'em loose (first time through on a flathead, for me). The only thing I can think of is to hope the tangs on the bar are thin enough to fit into the clip slots, hold tight against the opposite side of the intake hole and rubber mallet 'em on the driver's side of the block. (Prolly will ruin the guide that way. Yuk.)
Here's what it looks like (this is mainly #6, with #7 slightly visible to the left):