I believe Offenhauser has been out of business for a long time.  You should be able to get a intake gasket kit for an aluminum manifold on an Olds through any speed shop or order online from Summit or Jegs.

Yep still cant find anything that matches up. Looking up 455 Olds manifold gasket and they just dont match the ports, so I am assuming it's gotta be an Offenhauser gasket I need. Been difficult finding parts for this engine seems to be a lot of vintage parts I'm replacing here. Took me a bit to figure out my Frantz oil cleaner runs a roll of toilet paper LMAO was trying to find a filter for it

What?? I'm lost. Gaskets don't match the ports of WHAT? Ain't seen that yet on a 455, well, unless something weird like W2 heads or something.

455 gaskets are 455 gaskets, as far as I've seen. Only thing I know of first hand to NOT do on a boat is use the cheapass bathtub style. Use the independant Fel-pro's with gaskacinch and a generous bead of good gasket silicone on the end rails. 

Gaskets gotta match the heads, not the manifold, and if the maifild don;t match the heads, well, different matter. Perfection would dictate "gasket matching" both, but for most of us, who has time for those few ponies?

Are you serious on the oil filter? My Unc used to tell me about those, and yes they exist. Lose it on gthe boat, maybe sell it at a swap/nostalgia meet.........

Ray

That center set of holes is for the EGR/heat riser passages. Not used here unless you're smog testing the thing for some reason.......Everybody, even on the street, blocks them things off. Your intake probably doesn't have those holes either if it's a single plane.

Use 'em as they are! 

Remember, gasacinch and sillycone though! 

Ray

Are the valley pan gaskets any good? Still a lookin

What the copper gasket didnt seal?     go figure         run a straight edge on the heads and the exhuast logs if there not straight meaning FLAT no gasket will seal. you may have to have the logs machined flat. or the exhuast side of the cylinder heads machined flat!!good luck!!!

Just got the copper exhaust gaskets today so I will know tomorrow if they seal or not What I'm lookin for now is the intake manifold gaskets. Can't seem to find any with the same center hole like the pic I posted above. I have found some valley gaskets that are an exact match so I was looking to get some input on the valley type gaskets...

Thanks

Dont run the valley pan and the center holes are the when and u don't need them the gasket Will block them fine if it makes u feel better about It u could cut it out but i wouldn't its smog shit and not needed

X2. Don't cut the center holes out and stay away from the valley pan dealio. They are notorious for sealing problems causing milkshakes. The pic of the ones you were looking at are fine, Felpro Permaseals even better.

Somewhere, Don't remember if it's on this site or another, but Barry (obnoxious001) has a great step by step post on intake manifold installation. If I find it, I'll link it here for ya, but just remember to use Gaskacinch around the ports, and wipe some clear gasket silicone around the water jacket ports. Yes, both sides of the gasket, and I do the heads and mani also. I also throw the rubber end gaskets away and use the same gasket silicone (In a caulking gun) to lay down a nice thick bead on the ends instead of those things. If you're gonna use them, then the same thing, wipe some silicone on them, the block, mani and a little bead above and below them on the corners to help them seal.

Ray 

Glad to hear there is another 455 running now I just gotta get mine back together and we can have a olds race

Sweet im workin on gettin my boat together I'm down for some olds races when I finish it

Sweet u get urs back together?