Heat Riser Removal??? ... 68-70 340 HP Manifold
On my car, I decided to remove the heat riser flap but maintain the counterweight externally for original appearance. You will need to cut the welds on the internal flapper in order to slide the shaft and counterweight out. I simply replaced the shaft and welded it on the inside of the manifold to keep it from spinning.
If you have a replacement kit, it should include a new flap, thermostat spring and bushings for replacement.