heat rise valve blocked

hi all ! i' ve a problem: my heat riser valve is blocked, and i can't say exactly if it's in open position or closed. And for the moment , i' don't want to remove exhaust manifold , or pipe, because they are very very rusty and i' m afraid to break bolts. so, can you tell me: when the counterweight is high, the valve is closed, isn't ? and so, when his large end is looking down it's open..and i'll try to block it in that position.. Tanks. Phil.

Phil.....yes, when the weight is down, the plate inside should be open. The coil spring has two purposes. When the engine is cold, the spring constricts and closes the plate. This forces the passenger side exhaust to go through a passage in the intake manifold under the carburetor to warm it up. As the engine warms up, the spring gradually relaxes and the exhaust flows through the head pipe or "Y" pipe. The spring also is supposed to keep a slight tension on the counter weight to prevent it from flopping around. If you can move the counter weight freely, it is probably working properly......John