Technical WCFB vacuum advance port thread size?

Hello, I'm currently in the process of putting dual WCFBs (list 2197, for a 322 Buick) on my car, and am wondering what thread size and pitch the threaded vacuum advance port is? Only need to use one carb's port, obviously, so I need to plug the second carb's fitting. I don't have any thread chasers or taps that will thread in far enough for me to trust them, and don't want to just cram something in there that won't seal properly. If anyone knows I'd appreciate the info, thanks!

Lucas

 

try 1/8 NPT

 

Thanks, Jim. Will do.

 

I believe originally they are reverse or inverted flair, something like that.

 

I doubt it...the WCFB on my Vette has a br*** adapter to go from 3/16" inverted flare, to 1/8" NPT. Another WCFB I have sitting here has a 1/8" NPT pipe plug in it.

But it would be a good idea to look in the hole, if there's a seat for an inverted flare, try a 3/8 fine thread bolt to see if it screws in easily. But I'll bet it's pipe thread.

 

Correct, has an adapter, but the carb itself is 1/8" NPT. Lowes to the rescue for a couple bucks. Thanks again for the help, I appreciate it.