[cajunchevelle]

69 Chevelle, which way is the exhaust heat riser valve full open? with the vac on the canister, or with no vac on the canister. need to know which direction to tie it off in until I change the manifolds to headers.

Sos

 

[rustbucket79]

Vacuum applies the heat riser. (closes the butterfly valve)

 

[cajunchevelle]

Vacuum applies the heat riser. (closes the butterfly valve)

Thanks, it comes off tomorrow. So when cold, the therm switch in the water neck is open, allowing vacuum from the manifold through the switch, then pulls in the vacuum piston. Once the water temp warms up, the switch closes off the vacuum, I suppose the switch also has a vent to release the vac as well?

Thanks for the info. I now know which way to tie it off until I install the headers.

 

[RB69SS396Conv]

Yes that is correct. No vacuum = valve open. No need to "tie" anything, unless the spring is broken or something. Not sure how that would be a good idea, regardless; if the car is otherwise stock, it's designed to be there, and the car will work better WITH it than WITHOUT it, hot-rod mytholgy and lore notwithstanding.