Mike- I just went through this problem on my '51's 1956 235 heat riser valve. I started on it last fall, spraying, tapping (then beating), heating it with propane and then switching from PB Blaster to Kroil, with no results. Then someone mentioned that he had gone a different route by disconnecting the exhaust at the manifold and working on it from underneath. I hadn't even thought of that, and was ready to pull the whole manifold system and carb off to get to it from the top.
But after dropping he exhaust pipe, I found that I could shoot the Kroil up into the rod and valve points and do a little gentle prying on the flap (it still didn't budge, yet).
But after getting the oil on the inside mounting and stuck surfaces, and THEN tapping the counter weight and rod end at the spring attachment point, and also removing the oil filter casing for a better shot at the weight end, I felt a little give. After that, it was just a few minutes of tapping backward and forward and re-spraying the Kroil before I noticed a little give, then some more, then some more. It was moving, but wasn't moving freely, so I sprayed all points, on top and up through the bottom again, then grabbed the weight with my channel locks and moved it manually until it finally moved free enough to return to it's open position each time I let it go. I then sprayed the heck out of all points again, and it seems to be working like a champ now. I just got my new bi-metallic spring, exhaust gasket and new oil lines in yesterday, so I'm getting ready to put it back together today or tomorrow. But that thing was stuck tight. I thought it was more to do with the flap inside being rusted to the manifold, but after I got it away from the point of contact, I still had to keep shooting kroil on the rod connections inside and out.
Can't remember who suggested going through the exhaust pipe connection (Keith, maybe?), but I thank him for the idea. It worked for me! Lee Butcher
Last edited by showme; 06/04/2022 5:05 PM.
