Its quite possible u have an obstrucion somewhere too. I have an 88 302 that I put an intake on and had a hell of a time getting the air bubble out. Took it everywhere, tried everything to find out it was still doing it. As luck would have it I had a lifter go bad and had to take the intake back off and when I put it all back together it was sooo much easier to get that air bubble out! 302 are notorious for being hard to get the bubble out anyway. I used the same gasket sets and everything,bmust have just been just one of those things, or maybe even a bad gasket...anyhow, that is another possibility.