Stuck Heat Riser

[jhdeval]

I am not finding much information on this. Mine is stuck really hard right now. I have sprayed it with PB Blaster Penetrating oil a few times tapped on it with a hammer still no go.

What does this do? I am planning on pulling the intake and exhaust off to clean, paint and replace the gaskets as I have a leak at the head. Any suggestions for loosening it?

 

[memike]

I removed my slant 6 exhaust manifold and it was stuck over half way closed
I did everything you did with no luck at all ,that 66 heat riser was there to stay...
I had a friend cut it out from the inside with a metal blade on a air driven sawzall.
I did not want it in there any way, it is to help get the engine up to temperature and living here in Arkansas with a manual chock I did not need it to restrict my exhaust
We was going to use a torch and heat it but no gas..... I still have the manifold if I ever go back to single exhaust

 

[jhdeval]

Okay now that I have the exhaust apart I can see the heat riser is mostly open. I have instructions for removing the counter weight etc on the outside but can you remove the plate and pin?

I would like to keep it but obviously it needs to be removed and at least cleaned to make it operate.

 

[demon seed]

Okay now that I have the exhaust apart I can see the heat riser is mostly open. I have instructions for removing the counter weight etc on the outside but can you remove the plate and pin?

I would like to keep it but obviously it needs to be removed and at least cleaned to make it operate.

There is a bimetalic spring on the shaft of the heat riser (unless it fell off), so when the engine is cold the counterweight keeps the plate closed. Or they use either a spring or the counterweight, can't remember. Either way when you start the engine the exhaust gases are now forced to go through ports in the head to a chamber beneath the carb. This heats the incoming mixture until the exhaust manifold gets hot enough that the valve now opens. Unless you live in subzero temperature in the winter and drive it in the winter it's not needed. Yes remove the plate but keep the pin or you'll have an exhaust leak.

 

[Inertia]

we used to have to free them up on the car.. What worked for us, was soaking the shaft and bushings with good penetrating oil, then take 2 hammers, and tap alternately at each end of the shaft, tapping shaft back and forth, and repeat process, 2 or 3 times,, usually frees right up..