I recently got a 50 Chevy pickup project. Had no engine or trans; and I didn't have anything sitting around in my garage to use. A good friend knew his neighbor had an Olds 455 engine that had been in his garage for long time; turns out 26 years! Long story short, I got a 1968 455 with a 1975 T400 for a great price. Engine turns over with good compression. I think it's mostly original, has the correct C heads (which are good ones) for a 1968 engine. There is an older Edelbrock "Performer Olds 455" intake and Edelbrock carb on the engine. Also has an HEI distributor which is not 1968 stock. Somebody along the line changed those parts out. Trans checks out as a 1975 Olds version long tail T400. The seller had gotten the engine and trans with another car he purchased, but he never did anything with the engine and trans beside putting away in a corner of his garage. In addition, at a big car show and swap meet last weekend, I picked up a 12-inch higher stall converter that was new and just installed, but never ran. Trying to get the exact info on what it is, but it has HS stamped on it. High Stall is what I interpret that to be, probably something between 2000 and 2500 given the 12 inch diam. Should work nice with the 3.73 gear rearend I have for the truck. I think it will be neat having something different than the typical SBC used in these AD trucks; or worse one of the LS engines. Give me some Olds 455 advice for those knowledgeable. I'm not an Olds guy, but learning fast! Since everyone likes pictures, here it is cleaned up.
Great engine for a truck, but it may have 10.25:1 compression, and want high octane gas. Don't rev it to the moon (over 5000), and don't expect much oil pressure. ~10 psi hot at idle in gear pretty typical.
I've got one of those outfits - 455 with T400 - which I got cheaper than you. It was free and they delivered it! Son has a 455 and tricked up T200 in his 55 Olds and it amazes me that he can park it in the underground car park at the hospital where he works. It's still LHD and he says the biggest problem is swiping his card at the boom gate.
Great engine for your new truck. Not sure how much you’ll like the 3.73s on the highway though, I’d shoot for 3.23s or 3.55s. Are you planning a beautification program for it or will it be a rough n ready parts chaser? Either way, it’s gonna be cool. Congrats.
I own one of those. 68 455. This one got raced for a couple of years but is now retired to street use in my Olds. 11:1, 60 over, rollers, Mondello built, still scares the crap out me. Congratulations on a great engine...if your friends need stumps pulled out of their yards, tell 'em to give you a call.
So on the Classic Oldsmobile forum, the guys there figured out the trans is actually a THM-375 (or T375 for convenience), which is a lighter duty version of a T400. Smaller output shaft and less robust internals, but with the T400 case design. I'm sure it is sufficient for the power levels I am dealing with. Will have to consider maybe running a 200-4R which would give me OD to go better with the 3.73 gears for highway cruising. Needs to be a built up 200-4R though to handle the torque without problems. Decisions, decisions.... Happy that the engine is confirmed as a early 68 big car 455, likely a Delta 88 based on the plant code in the engine stamp ID. It might even be potentially forged crank, but that's only icing on the cake as I don't intend to be racing this.
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