Here’s my setup, got it hooked up late tonight, I attached it to spark plug hole because I couldn’t find a socket to get the other hole opened up. in my excitement I pulled 5psi but I forgot to remove oil injection tube and I didn’t tighten down intake manifold… never do anything in a hurry I should’ve known. Hopefully that doesn’t mess anything up. Anyway it’s too late to continue tonight. 

I sat down and did a proper test tonight. Pumped 5psi into it and it dropped to zero in 10 seconds. I could here the bubbling of air coming out so I went and mixed a bottle of good ol soap water together and gave all the seals a good soak. Pumped it back up and what do you know it’s the intake manifold! I’ll have to order a new one and a gasket. Maybe yamabond? I haven’t looked into how that is connected yet 

Interesting for sure but it'll never seal there without the carb holding it flat. Remove that fiber spacer & try again & should be good. In saying that i've never needed to do a vacuum test but looks like you have a good setup there.

I was wondering if the carb was what kept the leak from getting out of control but there definitely seemed to be a large leak along that seal. This one was a pressure test also 

Yes, I agree.  You aren't going to seal that bakelite heat spacer the way you are testing.  You could make a block off plate out of flat 1/4" steel plate and bolt that down in place of carb using gaskets on both sides of spacer instead of using the expandable freeze plug. 

 

Very easy to trace out the carb... if you can, make it out of aluminum.. quite a bit easier to work with..
Sneezles61

I thought this is what I saw others do but maybe their intakes are setup differently. I don’t have much to do metal cutting with but I can try and figure something out. Where are you saying I should put the gaskets Mark?