I'm confused dang it.

If you mill down Vortec heads for higher compression on a 305, don't you use a 305 head gasket, since it's a 305 block?

No article I've read addresses WHAT gasket the builders use, when putting Vortecs onto a 305.

They babble about thicknesses and CR's but never say whether they go with a 305 gasket or a 350 gasket.

Does anyone know which gasket to use?

A 350 gasket doesn't make sense to me, but what do I know... ha

Thanks guys.

 

I was always under the impression that the 305 and 350 gaskets were the same. But as you say "what do I know?"

 

That's weird because the bore is smaller on a 305.

 

They are not the same gasket. You should use whichever fits the head better. You do not want the fire ring of the 305 gasket to fall into the chamber on the head, that would be bad.

 

It's getting harder and harder to find a 305-specific gasket these days.

One is Felpro Q505SD.

 

Will those work with an aluminum head?

 

I was told also that the FelPro Z1094 .015 is a good one, at least for my setup, which will be 305 specific Vortec Heads.

 

If you are using the 350 L31 vortec heads or any other 350 head on a 305 use a 350 head gasket.. If you want a thin gasket use the felpro 1094 .015" shim 350 gasket
4.10" x.015" compressed.