big block is a big block?

[BlackTA]

Ok Im swapping out my 403 for something else because it blew. Please spare me the lectures on changing over to Poncho Power trust me I would love to change over but it will be easier to stay Oldsmobile and with lack of a parts car for the stuff to switch over everything I will just stay Olds. Anyway I have read posts of people switching from 403 to 455 olds but havent seen anything of switching over to 400, or 425 olds big blocks would the exact same problems show up as the 455 or will I need to watch out for other things also

[BlackTA]

Ok Im swapping out my 403 for something else because it blew. Please spare me the lectures on changing over to Poncho Power trust me I would love to change over but it will be easier to stay Oldsmobile and with lack of a parts car for the stuff to switch over everything I will just stay Olds. Anyway I have read posts of people switching from 403 to 455 olds but havent seen anything of switching over to 400, or 425 olds big blocks would the exact same problems show up as the 455 or will I need to watch out for other things also

[Bill Morgan]

You will encounter the same problem with a big-block 400 or 425 that you would with a 455, because the block dimensions are identical for all three.

You can replace that 403 with a 350 Olds as a straight bolt-in.

[Mr. P-Body]

Another issue regarding Olds 455 versus the 400 and 425. parts. 455 parts are still readily avilable from most aftermarket suppliers such as Sealed Power, Clevite, etc. You will jump through hoops, or go to an Olds-specific place, to get pistons for a 400. 425 parts? ***gettaboutit.... The 455 would be a much easier ordeal.

[BlkBird]

The 400 Olds is a different family then the 403. Everything will most likely be different and it will be a difficult swap. I loved my 403 so I would never try to talk anyone out of one but Im not sure why you think it would be difficult or you would need a parts car to swap in a Pontiac motor. The 400(Pontiac) will drop right in with no other mods. All you would need is the complete motor.

[BlackTA]

the pontiac 400 motor has different engine mounts as well as brackets and other things or so im told