66 Olznut

Looking for more stuff for my build and while looking up ARP's listings, they have stuff for the 350-425 and stuff for 455 specific. Can someone clarify this and tell me what I need for my 400? I thought 400-455 was the same?

joe_padavano

You are correct. All BBOs use the same bolts, some of which are different for SBOs. As usual, the catalog is incorrect. Just get 455 parts for your 400 and ignore what the catalog says.

cutlassefi

But if you're changing the bolts I'd have the align bore checked as well.

Fun71

Joe, the rod bolts for the 425 are the same as the SBO (330, 350) - so they are different than the other BBO rod bolts. The remaining bolts should be the same as the 455 and later 400, though.

64Rocket

early 400, 65 to 67 use the same rod bolts as the 330, 350, 425.
Rod bolts for the 455 are the same as the late 400, 68/69
You always re-size the big of the rod when changing the bolts
You hone the big end of the rod, align bore is for the mains, then you align hone to spec.

Gene

joe_padavano

I did not know that the early BBOs used the SBO rod bolts. I would have thought that the 3" journals required longer rod bolts for all BBOs (and diesels).

cutlassefi

Ummm Joe, the rod journals are 2.5", not 3".

But that doesn't make sense to me either. Then again I don't believe many of the part numbers given for Oldsmobile pieces.

joe_padavano

DOH!

Haven't finished my first cup of coffee yet.

66 Olznut

Dang, I just got the bolts here, time to exchange them. Just to clarify, the rods use the 350-425 bolts (#184-6021) and the mains use the 455 bolts (#185-5001)? Those were the only 2 that I wasn't sure about.

jensenracing77

I have a new set of ARP rod bolts in the package for a 455 if you need a set. I would let them go for $55 shipped. Send me a PM if it is something you need.

66 Olznut

Thanks Jensenracing but I ordered them before I asked and I now have them all here, lol. I'm guessing the rod bolts will need to be exchanged since I got the 455 ones and I'm seeing I need the 350-425 ones, I'm building a '66 400 and I thought all big block stuff is the same.