Ive got large oval port cc heads, should I only use an oval port intake? Or can I use a rectangle port manifold as well?

I've got large oval heads (215 casting) and am running an Offenhauser rect. port intake, no problem! Just use the rect. port gaskets to seal it up.

Sounds good, thanks Rich. Im still debating what manifold I will get. I read alot about those Offenhauser intakes, I will probably end up with an edelbrock air gap 7561.

Racer1320 uses a rectal port intake on oval port heads also.

EDIT: minor port done to the heads to get a better match to the rectal intake.

I ended up using the Offenhauser (rect) intake because I wanted a low rise (not tunnel ram) intake that I could run 2 holley carbs inline on. From what I've read and been told, there's not a big advantage to running rect port intake on oval heads, but it definately does not hurt performance.

Originally posted by rich1978:
I ended up using the Offenhauser (rect) intake because I wanted a low rise (not tunnel ram) intake that I could run 2 holley carbs inline on. From what I've read and been told, there's not a big advantage to running rect port intake on oval heads, but it definately does not hurt performance. =
In my opinion when just bolting on an intake, this is simply not true, it will hurt potential performance.
There was a very good reason to use the GM rect port intake about 30+ years ago & it was because it was better than any of the crap out there.
This is no longer true, there are some excellent intakes now & to run a rect intake on ovals without some kind of port matching is very much going to hurt airflow.
Don't believe it?? Spend some time on a flow bench & see what the difference in cylinder head flow is between a bare port & one with a radius entrance. It is huge.
Think about what is going on here. Air is not "drawn" into the cylinder, it is being forced in by a higher pressure area above the cylinder.
When the air hits a small hole or port without some sort of guide or no "entry" the air has no clue what to do, fuel if present is separated from the air stream, the air that hits the head has no where to go, the boundary layer is completely upset & it causes the port to "look smaller" the higher the velocity gets, the list goes on & these are all very bad things when it comes to airflow & even worse when a liquid is added to the mix upstream of the sharp edged smaller hole.