I'm trying to plug the 3 ports on my crossover tube to delete the smog stuff on my 72 with a 75 engine and mix of SU carbs. Can't seem to find what will go into these and close them up.

Found some rubber caps to go over the 2 matching fittings at Home Depot, inserted a threaded plug into the other, works fine.

Do you happen to remember if the threaded plug was NPT (tapered National Pipe Thread) or was is something metric? The 2 with vacuum hose attachments seemed to fit 10mm x 1.0m threads on the thread tester at OHS but they didn't carry anything with such fine threads (only 10mm x 1.25). I checked at Kragens and they thought it was 3/8" NPT and not metric.

I haven't even checked to see what I could plug the larger one with.

American Pipe taps are close enough to chase the threads and then install standard Allen head pipe plugs the soem teflon sealer. Don't have to chase arounf trying to find metric.

Those ports on the manifold and the fittings installed in same happen to be "BSPT".

BSPT is British Standard Pipe Threads and the size and thread count are close but different than the "NPT" common in USA.

A purist would take the time to buy plugs that fit properly. Parker Hannafin fittings which can be ordered via Hydraulic Fitting specialty shops used to stock BSPT plugs in different sizes and materials. I ordered plugs for my manifold thru a local shop.

If you are not a purist and respond WTF you can simply buy some NPT fittings in the ballpark and just jam them in and force the treads to adapt.

A "purist" would leave all that stuff hooked up. Factory original pipe plugs? Now that's too funny......

I would probably do some research and find all the proper hoses that go on those connections. That might not make me a PURIST, or it might it doesn't matter, but I would have piece of mind about what's going on under the hood. But that's just me. I actually ran a vacuum gauge off one of those fittings.

Tracking down a European E41 balance tube would make a clean set up.

agreed....get a euro balance tube with block plates installed so the air doesn't share, then run cable lifted carbs, instead of the SU carbs. Got ahold to (2) 42mm mikuni's i'm working on fitting to my 2nd 260 atm