Not going to be ideal be any stretch although it will work. Ive never found the rectangle port to be to lazy on a 454 anyway. Marine engines love free flow. That being said, I have 2 brass lined merc dual plan rect port intakes (spreadbore flange) for sale if youd like to do it right. 717 725 4508 dave

The rectangle port intake on a peanut port head is what works. Not the other way around. I advise you buy the correct intake for your heads.

The rectangle port intake on a peanut port head is what works. Not the other way around. I advise you buy the correct intake for your heads.

pm'ed you

Anybody care to elaborate on the mercruiser rec intake port with small oval port head combo...was it a crappy combo? Any better combinations?

There was an article in car craft on this. I cant find it though.....

Okay,listen,I am old and dealt with this back in the day. The Ford guys dealt with it too when there where only good intakes for the big port heads.

There where no good intakes for the smaller heads. So we used the rectangular intakes. Not a real good thing to do,but better than the alternative.

As of 530 million years ago the aftermarket came out with really good peanut port oval intakes and large oval port intakes. No need to deal with that mismathing stuff again.

And again,this thread is about oval intakes on rectangular heads.As imentioned before, good luck finding aovalport intake that will cover the rect ports on the heads and seal them.I believe there are only two. A Dart oval port single plane intake and some small 177cid or the like supercharger intakes.

like your quote.....................
as already mentioned,,would an oval port intake cover and seal on rect head???
i acutally did put rect port intake on oval port head ,,back ,,years ago when jimmy was president......car ran,,,but ..

Use a rectangle port gasket , put it on , and dont worry about it .
You will never know it , If you wanted to spend the money to dyno it , I bet it would hurt your feelings with the results .
It may show 1 or 2 HP either way . but usually in low rpm app , the mismatch of smaller intake and larger head sets up a reversion damn .
Its like using a 4 hole carb spacer on your intake. Helps with the plenum pulsing from reversion , Even bigger benefit if
you have a large duration cam.

So I finally got time to get out in the garage the other day and put the intake up to the head. The manifold itself does not cover the rectangle ports on the heads, they are too tall. Had it covered the port, I would have probably ran with these intakes. I appreciate all of the input from everyone