I recently bought a new master cylinder for my 90 FC RX7. The new master cylinder has a threaded port on the bottom. The old one does not have this port. Its just a flat spot with no tapped port there. My question is, is there a plug i can buy to plug this port? I can not find anything with that fine of threads. It appears to be a really fine thread. Something around the size of a 14mm bolt.

 

It's a spot for a pressure sensor.
When your "pedal hits the floor" due to a leak that sensor lights up the light in your Idiot cluster.

I may have one..If you need it.
Just BUG me for it..Pm me..I tend to get "busy"..!

 

its for the AAS brake pressure sensor, there are i think 5 different master cylinders for the FC, there is the normal one, then with AAS (that sensor), then AAS and ABS, and then ABS without AAS, and then the S5 turbo. there is a 6th, in japan for the non ABS cars

 

Long story short, I think i am just going to tap it out to a 3/8" pipe thread, and put a pipe plug in it. Problem solved.

After doing a lot more research i am starting to see all of the different ones available. Just to bad that most sites online do not differentiate between them.