Just finished building my 525sc motors using eq320 heads and stock intake manifold. I used felpro 1275 gaskets. Started engines and discovered vacuum leaks out of the 4 unused bolt holes. Did I use the wrong gasket? If so which gasket should be used?

I've had to tap and plug those unused holes on other rect intakes installed on other performance rect heads that do not have the threaded holes in between the intake runners.. You'll have to take a look to see if you have to do the same.

Fel pro 17342 is what I used same engine going to start it this weekend. So we'll see

tap them to 1/4" pipe thread and install some plugs

I've seen the Felpros suck into the port, weirdest thing. I have a photo of it somewhere.

I used the MR. Gasket 121 on mine. My intakes also have the upper bolt holes (unused). When installing the gaskets, I put a light bead of "right stuff" around the ports, as well as the water ports. A little trick I learned from mike tkach years back. Its a bit of a pain to get off if you need to pull the intake off, but , those fukers are sealed up once its torqued down.

Thanks everyone. Guess I'm pulling intakes this weekend.

the problem with the fel pro gasket is it can allow air into the unused boat holes.i like the mr gasket 121,it does not have this problem.i have filled the unused bolt holes with the right stuff if using the fel pro gasket and it works.

i have plugged them with a 3/8 set screw and lock tight.then put the right stuff over it to seal it at the gasket.

So, the bolt hole in the head goes thru to vacuum?