1968_Post

I'm about to start the swap from the junkyard smogger 350 that exists in my 442 to a 68 455 I recently found. While the engine is at the machinist I'll be pulling the 350 and removing parts that will change over to the 455. I have a couple of questions about what will interchange:

Does the oil pan interchange or do I need to buy a 455 pan?

All the brackets are of a mid 70's design. As this is a driver and not a points car, I intend to use what I have, including the later style alternator. Posts I have read here state that all pulleys and brackets will interchange, but I guess I'm just looking for reassurance.

Other than motor mounts and brackets, is there anything else that I'll need to procure?

As always, I appreciate the input that comes from the site...

Thanx,

Jeff

Warhead

Oil pan will interchange, BUT the pan is different.
BB pan has slightly diff shape, and a baffle.
I have a greasy one for $25 and the ride.
You may need a bushing/spacer between alternator and power steering.
Headers are different.

1968_Post

Headers were another question... this car has a high dollar, professionally installed system with ceramic coated headers that have burned off most of the coating. I thought the exhaust preceded the engine swap, but since 350 and 455 headers aren't the same, then I dunno...

joe_padavano

NOOOOOOO....

One more time, so long as the rubber motor mounts match the frame mounts, ANY 1964-1990 Olds motor bolts in. More importantly, if the car you are talking about is a 1968, then the factory used the SAME motor and frame mounts for 350, 400, and 455 motors.

s i 442

But if you don't get the frame mounts for the 455 then the engine mounts are going to sit different.

joe_padavano

NOOOOOOOOOOO!

PLEASE READ THIS THREAD:

https://classicoldsmobile.com/forums...tion-list.html

The block is irrelevant - ALL 1964-1990 Olds V8s have the motor mount holes in EXACTLY the same place. So long as the rubber motor mounts match the frame mounts, the engine will NOT sit "different". And contrary to what many vendors list in their catalogs, for 1968 the factory used the same frame and motor mounts for big and small blocks in the A-body cars.

DO NOT change the frame mounts. DO use the motor mounts that match the frame mounts. DO NOT overthink this.

s i 442

I put a 455 in a 71 Supreme one time and used the 350 engine mounts and the headers would not fit, I went to the parts store and ask for 455 engine mounts and installed them and the engine sat up higher and the headers went in no problem???
(This is a true story)!

joe_padavano

I give up. Some one else feel free to jump in.

Kennybill

I was one of the lucky one! My headers fit in my Supreme. Lol My 1967 Olds 98 is rumored to have an internal roll cage. Ken

Warhead

Unsure of your vehicle, but the blocks are drilled in the exact same spot. I have done this sway plenty of times, and what Joe said IS correct.
BBO frame pads-BBO mounts
SBO frame pads-SBO mounts
Put a 455 into a 1978 and later 260 equipped car? Use the 260 mounts.
455 into a 330 equipped 65 F-85? Use the 330 mounts. Use the motor mounts for the pads that are in the car. Simple.

ALL of the blocks are drilled in the same place.
You will be okay.

joe_padavano

And just so we're all clear, prior to the 1969 model year, there was no "BBO/SBO" mount distinction. ALL 1965-1968 Cutlii used the same frame mounts and motor mounts (the 2261 equivalents) for ALL size motors. Full size cars have also always used the same frame and motor mounts for ALL size motors. The block doesn't care which mounts you use. The FRAME MOUNTS do care and thus the motor mounts must match the frame mounts.

Yes, I do get tired of typing this...

Rickman48

And if new motor mounts gave you more clearance for headers, it was because the old ones were probably mush from being oil-soaked, and collapsed!

RhinoGTO

Just went through this recently...

-You will need Big Block headers
- If your car came from factory with 350 and you have the original motor mount pads then you will use 350 motor mounts.
- I needed a spacer between power steering and alt bracket since alt bracket will sit higher than 350 due to taller deck height on big block.
- Also need a new longer alternator belt.

Thats it!

joe_padavano

This depends on the year of the brackets and whether they are for A/C or not. Non-A/C alternator brackets have two sets of holes in the strut that goes from the "Y" bracket to the water pump bolt, so it fits both deck heights. Even A/C alternator brackets on 68-70(71?) motors don't need the spacer because they don't touch the PS pump bracket. The pump bracket has the triangular link that goes to the front exhaust manifold bolt and it also has two holes for both deck heights.

455man

I almost threw out a set of alternator brackets that I could not identify or figure out where I'd got them. Then I read a post like this with a pic and realized(after I put a 1 in spacer in my brackets) that I had those BBO/SBO brackets.
Also you will need to move the brake proportioning valve for the BBO headers.