merc 454 intake gasket square or oval ?

[2kjs]

Hello all, I'm getting ready to replace the intake manifold gasket on a 1980 mercrusier 454 (330hp) would like to order gasket before I start the project, but looks like i need to verify whether this engine has square or oval ports. It has a 4 barrel quadrajet carb on it. Thanks in advance for the help !

 

[picklenjim]

Re: merc 454 intake gasket square or oval ?

This can be very confussing as different people use different terminology when identifying big block heads. They make a rectangular port head which some will call square port. Then they make a large oval and the peanut port head which some call small oval. The peanut port (small oval) is actuall more square shaped. So when they say square port are they talking about small oval (peanut port) or rectangular? When they say oval are they talking about large oval or small oval?

I can tell you this, the rectangular port is the high performance head. The large oval is also a more high performance head.

To the best of my recollection all 330's came with the small oval (peanut port) head which is actually more square shaped. In the Mercruiser Service Manual it says a 330 has cast iron oval port heads.

The peanut port (small oval) are 1.6" high by 1.7" wide.
If you pull your valve covers off you can look at the casting number under there and maybe that will help.

 

[tpenfield]

Re: merc 454 intake gasket square or oval ?

Hello all, I'm getting ready to replace the intake manifold gasket on a 1980 mercrusier 454 (330hp) would like to order gasket before I start the project, but looks like i need to verify whether this engine has square or oval ports. It has a 4 barrel quadrajet carb on it. Thanks in advance for the help !

Double-check the model year on that Mercruiser 454 . . . you can go to http://www.mercruiserparts.com or http://www.perfprotech.com
to verify serial number and year, then look up the correct intake & gasket . . .

It is likely the oval port style, base on 330 hp, but you should be sure. Also, you may be able to tell oval versus rectangular, just by looking at the manifold.

 

[picklenjim]

Re: merc 454 intake gasket square or oval ?

There's no way it's rectangular if it's a 330. As stated the different terminology used is what's going to confuse you. Will it be large oval or small oval? Small ovals are also called peanut port yet they are more square looking than oval.

 

[wingless]

Re: merc 454 intake gasket square or oval ?

My 454 MAG MPI 380hp Horizon uses the rectangular gaskets.

Use the engine serial number to discover the correct gasket part number.

 

[2kjs]

Re: merc 454 intake gasket square or oval ?

Thanks for all the info guys its greatly appreciated, i'm going to get the serial number and go from there! And hopefully this will end the ongoing issues with my normally reliable 454.