1968 Thermostatic Vacuum Switch: Seeing that a nice used one of these sold for $311 two days ago(Item 250094251473), it appears I'll be repairing the broken one I have.
Actually this should be simple if I use a good epoxy - right?.
Has anyone glued one similar to this - any advise?
Here's a picture if it. It appears to me that the hot coolant temperature causes the element to move out and slides the piston inside the case and switches the vacuum ports.
Ames has the five port, I bought one last summer. I beleive it sells for about $45 if I remember correctly. But they do sell them, and to my eyes, they look absolutely identical to the original...
My question is this, do these things even really work? I bought mine hooked it all up and could never tell if and or when they were actually working. I bought it because it looks stock and kinda looks cool to have. LOL
The TVS is a device that helps protect your engine from overheating. It functions from coolant temperature. In rest position ported vacuum from the carb controls the distributor advance. When it heats up above 230 degees F, it changes position and advances timing by 20 degrees which helps the engine cool down. After it cools down it switches back. Unless your engine overheats, you won't know if it works.
The Pontiac Service bulletins have removed the vacuum retard function from the thing so it should have no function if hooked up per GM recommendations.
I've often wondered if some of the people who have had overheating problems on the many threads here are the result of removing the TVS. The TVS is a safety device but a lot of people feel they have no purpose. I disagree.
The TVS is a device that helps protect your engine from overheating. It functions from coolant temperature. In rest position ported vacuum from the carb controls the distributor advance. When it heats up above 230 degees F, it changes position and advances timing by 20 degrees which helps the engine cool down. After it cools down it switches back. Unless your engine overheats, you won't know if it works.
The Pontiac Service bulletins have removed the vacuum retard function from the thing so it should have no function if hooked up per GM recommendations.
I've often wondered if some of the people who have had overheating problems on the many threads here are the result of removing the TVS. The TVS is a safety device but a lot of people feel they have no purpose. I disagree.
Jim, It is a safety device to help prevent engine damage from overheating. Good to hear you have had no problem but perhaps you have not encountered the problem that it helps guard against. A lot of people don't wear seatbelts either. They are fine until they need them.
![[Linked Image]](http://i26.photobucket.com/albums/c128/youngdw/TVS.jpg)
