Use wax to penetrate it plenty of threads on it. IT WORKS!
Also realise that you may or may not be able to get this valve to unstick and stay unstuck. After many decades and thermal cycles, sometimes they're just done, especially this early (pre-'71) type. /QUOTE]
Cool stuff Rusty. And I like the way you routed your heater core hoses away from the valve cover. Mine were shorter and went right over the top. And is your battery cable to starter routed to spec? I have that hangar on my manifold, but mine was wire tied to a power steering hose.
Just got it back on the road and the exhaust flapper valve that was feeling so nice and free out of the vinegar bath is sticking at operating temperature.
I hate to wire it open while I chase a couple dozen other more important tasks on the car but that may be where I'm headed. Letting it stick when the valve is closed seams like the worse of two evils.
There is no "open" or "closed" on the Slant-6 valve; that's on V8s. There's "heat on" (rotated full clockwise as viewed from the front) and "heat off" (counterclockwise).
I'll look for the grooves. Layson's is local to me, I'll see if they have the clips too.
Dude. No. Not unless you want to massively overpay. We're talking about ordinary, standard hairpin clips. Hardware store, outta the Hillman, Jandorf, or Dorman drawers. Like this or this.
Don't go running to throw money at specialty boutique suppliers for standard hardware items. And think very carefully and do a good bit of research before you decide to spend money at Layson's for clips or anything else. See, for just a few examples, here, here, here, here, here, here, here, here, here, here, here, here, and here. Much of what they sell is not of their own manufacture; a large proportion of their product line is bought elsewhere and marked up. They're almost never the only source for a part; see here for a listing of some more reliable vendors.