thread sizes

[mbarjbar]

I am eliminating the smog stuff on the balance tube on the intake manifold of my 1970 Z. I want to put a threaded plug into the larger hole near the PCV valve and in one of the smaller vacuum barbs on top of the balance tube. Standard NPT 1/4 and 1/2 plugs look close but do not work. Anybody know the correct (?metric) thread size for these openings?

Mike

[beermanpete]

We plugged most of the vacuum ports on ours and I recall using some 3/8 NPT plugs.

[Bruce Palmer]

Run the holes with NPT taps and they'll readjust the threads just fine and NPT plugs will work...... just fine. Maybe ad a spot of sealer.

In the words of Gunnery SGT. Thomas Highway "You have to learn to improvize, adapt!

[zKars]

Search here for BSPT and you fill find the exact sizes, but as Bruce says, and as I have done just about everywhere, run an NPT tap into them then use an NPT plug.

The recent thread I remember mentions Grainger and maybe McMaster Carr as sources for BSPT fittings if you must do it "right"

[mbarjbar]

Thanks Guys, all good advise.