[Jimbro727]

Originally Posted by Doug Christie

There were many heat activated vacuum switches to control various pollution control devices back in the day. The heat from the manifold or water crossover would activate the switch and allow a vacuum signal to activate another switch at a pre-determined temp.

You can check your PCV valve by pulling it out of the valley pan and shaking it to see if it rattles. Best to just buy a new one if in doubt. As far as hooking it up with the new manifold, it just heeds a large full vacuum port, like the one that my be on the back of your carb.

The line for your modulator should be hooked up tp a full vacuum source like from the back of your carb that feeds the vacuum to your brake booster.
If you have a vacuum guage, you can check the ports on your carb to see if they are ported or full vacuum. The ports that are near the base of the carb are usually full vacuum.

OK cool, thanks! I'll definitely check the PCV valve.. and maybe this is a stupid question, but how come mine is in the valley pan instead of on the valve cover like in the pic Serge posted? My Holley has a port that the instructions say is for the PCV, so when I change the manifold should I just hook up the PCV valve to that? It looks like it's the correct size. Also, I looked for a vacuum guage at AutoZone, and all they could show me was a boost/vac guage for inside the car, nothing for a diagnostic purpose.. I looked all around and couldn't find one, where would you guys recommend I find one? Is there a website or store or something?

Oh, and when I change my intake manifold, I heard that it's a good idea to change the valley pan, too.. is this true? I looked around for a valley pan, but couldn't find one, just lots and lots of gaskets, so if you think I should change it, can you recommend somewhere to pick one up?

Thanks again for the responses!

--Jimmy