Bennettre46

I own a 1968 Oldsmobile Holiday “S” 2 door coupe. I currently have the bone stock 350 rocket with an automatic 2 speed transmission behind it. I have found a 455 rocket block that I will be picking up on saturday to rebuild because I am looking for more horsepower, but want to keep it correct. What transmission should I put behind it? And is there anything I should be looking for in this motor other than obvious cracks? I only need the motor for the block, crank, and rods. I am planning to buy everything else aftermarket. Will some of my pulleys and brackets from the 350 work on the 455?
Thanks,
-Jayden

matt69olds

Technically, since it’s not a Hurst Olds, no 68 Olds A body cane factory with a 455 so technically, it won’t be “correct”. However, to do the conversion PROPERLY, you have a couple options. A TH350 trans could be built to handle the 455 torque. I have discussed the modifications needed to reliably build a 350. A TH400 trans is also a option, and will have far more power capacity, but requires driveshaft and trans crossmember modifications. Those modifications will require more changes to the emergency brake cables, plus some minor wiring changes to make the kickdown function work.

To make the 455 swap “correct”, as well as functional, most likely your going to need some cooling system upgrades. There are other little things that will need to be addressed to make this swap, but for the most part it’s about as close to a direct swap as can be expected. It’s been done to countless other A body cars, so your not on uncharted territory.

As for what to look for with your engine, I assume your looking to rebuild it? What year is the engine? What are your ultimate power goals? Find a machine shop familiar with Olds engines. While the machining of a Olds engine is no different than a ford or Chevy, the machining clearances are. If they machine clearances like a typical brand “X”, the engine will clearance itself, and “clearance” a bunch of space in your wallet.

Bennettre46

Thanks Matt, The motor is from 1975. I do not know what it came out of. And yes I am planning to rebuild it. I was leaning more toward a TH400 transmission. As far as power goes, I am just wanting some more get up and go that what I currently have. Probably upwards of 400 HP or so.

Koda

How can you plan to keep it correct when you are replacing everything above the short block? I recommend get the entire 455 engine, pan to air cleaner, flex plate to fan, and see what you got. A lot can be done to the stock parts without needing to get wild on aftermarket stuff, which will save a ton of money and fitment issues.

Bennettre46

Sorry, by "correct" I suppose I meant I'm not dropping an LS in it.

Koda

That's good. I didn't understand. A 75 455 will probably have J smogger heads on it. A set of C cores could be obtained and machined, and maybe an aftermarket intake, and headers, and different pistons and a good cam, and you could have something that looks stock but has 400 horse.

Bennettre46

Thanks, that's what I was thinking. And I am not as worried about stock look as I am performance and cooling. After some digging and questions, I figure I am going to have to get a bigger radiator. I have heard the "champion" and "be cool" brands are pretty good. Any preference here?

matt69olds

Unless you can capitalize on someone else’s misfortune, it’s difficult to properly rebuild cast iron heads economically, compared to aftermarket aluminum. Since your starting from scratch with the J heads, just go aftermarket. Shoot for around 9.5 to one compression, mild cam, and the aftermarket heads, you will be closer to 500 hp without even trying.

matt69olds

Let me know if you need any more LS swap assistance!

64Rocket

When installing the 455 in place of the 350, use the motor mounts for the 350 engine. which the part number is 2261 for both sides. will be a drop in.

Gene

Bennettre46

Good morning. I picked up the motor on Saturday and have cleaned off some of the grease. I have found the numbers but do not have a book yet that I can look them up in.
The casting number is: 396021F
The stamped number is: 35M159071
Thanks for the help.

joe_padavano

The VIN derivative shows that to be a 1975 smog motor (the "5" in the second position is the model year). I assume it has "J" heads and a smog-friendly cam.

Bennettre46

Thanks Joe, it does have J heads. Is there a way to tell what the motor came out of?

joe_padavano

Not easily, and frankly, I'm not sure it matters. There were only two 455s available in 1975, the VIN T 190 HP version and the VIN W 215 HP version. Both were single exhaust due to the catalytic converter. Both were 4bbl motors. Both were low compression with small valves. The real difference was the cam and distributor timing.

6T9442Drop

haha. Thats funny

Miles71

I have a 10% Horsepower rule!

You can upgrade the horsepower of most cars by 10% without modifying any of the supporting infrastructure (Cooling, brakes, suspension, etc).

And sometimes you may get lucky with a 20% Horsepower increase without major updates.
The 1968 stock 350 came with about 250 BHP.
At 10% increase would be about 275.
Sine you plan on going to 400 HP you will need to update the following items to support the new 400 HP beast.

Everything!

Transmission TH-350 to TH-400
Drive shaft (update to support 400+ hp)
Rear differential (update to posi traction and 400+ hp).
Front and Rear Breaks, convert to disk to make you STOP the 400 HP beast.
Radiator, convert to a 4 Core copper. Electric cooling fan optional.
Optional Oil cooler.
If your suspension system is old, then replace it.
Add a rear sway bar and all of the required supporting system [Boxed lower control arms, etc.]
Replace springs and shocks to support the greater weight and expected driving style changes.

You don't need to change the Paint or Interior.

bccan

My two thoughts are, budget allowing, go roller valve train to make initial break in easy and not having to worry about additive levels in oil for the rest of the engine’s life. Only TH350/400 transmissions have been mentioned, if starting from scratch I would suggest considering a well built 200-4R, especially if any stouter rear gears might be in the future. Any gear from 3.08 or lower loves the OD & lockup, some have even used them with higher gear ratios but I believe that to be marginal. The 200 would be more expensive than TH350 but they have become a very popular modification with easily managed peripherals akin to a TH400 swap, not sure of $ difference with latter.

My 2 cents contributed FWIW, kinda fun spending other people’s money!

Rocketguy

My '66 Toro powered wheelbarrow will blow the lid off your trash can.

joe_padavano

I gotta say, that's one heck of an impressive wheelbarrow.

Now post the video of you lifting it and pushing it around.

Rocketguy

I know right?

I pulled that engine from a car in a salvage yard with their portable hoist. I went to the front of the yard and asked how to pay for it. They said you have to put it in a wheelbarrow and bring it to the front building past the point of sale. I told them that engine would crush a wheelbarrow. They sent a guy out with me and sure enough, it held that engine. Now I'm a bit of a runt: 5'-11" but I only weigh about 150. After we loaded it I just looked at the guy, and he just looked back. It was about 100 yards to the front. I told him there's no way to push that wheelbarrow up there. He was shorter than me but more stocky. I'll be darned if he did not pick up those handles and push it to the front.

I was wrong a lot that day.



.

joe_padavano

Great story!

Back in my young and stupid days (mid-1970s) I pulled a 215 from the local yard for my V8 Vega swap. A dressed 215 weighs about 320 lbs. My friend and I literally grabbed the exhaust manifolds and hand carried that lump out of the yard and into the back of my 68 Vista. I can't imagine doing that today!

I should add that the 215 followed me from central MA to college in Cambridge and finally to the west coast when I got my first job in L.A. It didn't get rebuilt and go into a Vega until the early 1980s.

Koda

That's impressive. Best claim I can make is the entire interior of an El Camino, dash, bench, door panels, belts, trim, headliner, carpet, kickpanels, vents, back cab trim and its carpet, all stacked on the bench seat, and ceremoniously picked up, carried 5 feet across the "25 bucks for all you can carry in one load" special, and set down, and my buddy and I paid 50 bucks since it took two of us.

Rocketguy

Great story! Doubt that I could've done that in the 70s. Got any pics of the Vega?


Also a great story.

joe_padavano

I've got paper photographs someplace, but finding them is a challenge. I used the D&D kit for this swap and ended up getting the Motion four row Vega radiator.