I am changing the vacuum lines out on my 84 GSL-SE and broke this off. It looks like a one way valve but not 100%. Any one know what this is and where I can buy one?

 

Call Chris at rotaryperformance
He might have them laying around.He is helpful even with little things like that.lmk if you need his #

 

Yep, one way valve.

Mazdatrix sells them, but I'm sure you'll get a better deal posting a want ad or searching eBay.

 

That is the one way vacuum valve that supplies vacuum to the thermowax pellet at the firewall side of the throttle body. These typically run just over the upper intake manifold runners and just under the air tube leading to the throttle body. HTH,

 

How important is it? If I just run a line with out it, will it affect it much?

 

Without it you could damage the thermopellet