I recently purchased a 455 to replace the little 6 cylinder in my M715. I have been looking through summit and I see plenty of aftermarket stuff listed for the Olds and Pontiac 455 but not Buick. What if any are the differences in the different manufacturers engines. Can most of the external (bolt on) stuff be interchanged. I also assumed gaskets would be the same for similar year models? I am not sure on the stock specs for the motor (I know they are pretty decent) so if anyone could fill me in.. It is a 76 and model and out of a buick but I am unsure of the make of the car. I plan to use a TH400 from behind a Buick 350, from what I can gather from reading posts it should bolt up. Thanks for any information. -Steve
The BOP's share very little beyond cubic inch designations. You could swap a carb if necessary or maybe a distributor cap and rotor. They also share trans bellhousing bolt patterns. Beyond that, you're pretty much out of luck. You may want to check out www.taperformance.com for your Buick needs. You mention a TH400 behind a Buick 350. I'm assuming there was a swap done since that trans didn't come behind that motor in any car as far as I've heard. But, if it's mounted to a Buick 350 it should bolt up to your 455. Oh yeah, what's an "M715"?
Steve is right on the money, the three Corporate cousins all had 455s, but they are not the same engine by a long shot. Buick made it's own engines, except for the L6 six cylinder, until 1976. The reason Buick, Olds and Poncho have 455s is that GM removed a Corporate Ban on engines larger than 400 cubic inches in intermediate cars, that was in place until the 1970 model year. Chevy responded with a 454, all the others went to 455 (except Cadillac), which I believe was the new cid limit. Caddies were not intermediates and were immune from the ban. No parts will interchange and no gaskets will interchange other than the odd carb to air cleaner gasket or PCV valve or carb or power steering pump. Buicks used tolerances tighter than other divisions and require attention to tolerances and torque much more than say, a Chevy engine. Even the Q-Jet for each division was slightly different, Buick using a larger cfm unit, and is visually slightly different from a Chevy's- the fuel inlet, for example, is in front on a Buick Q-Jet for a 455. GM had bans before this, on cid up to 330, if I remember correctly, which is why you see a lot of 327s, 329s, 328s, etc. in the mid '60s GMs. If you have a Buick 455, look no further than TA Performance in Scottsdale Arizona. They have a banner link on the main page. The way to tell if a Buick tranny is a TH400 or a TH350, aside from the shape of the tranny pan, is look and see how the tranny is downshifted or 'kicked down' at full throttle: the TH350 Buick used a cable on the gas pedal just above the throttle cable in most cases, the tranny kickdown does not go to the carb in any that I've seen including mine, it goes to the tranny. Some other designs use the carb bracket to mount another cable, the Buick goes right to the tranny in my experience. Conversely, the TH400 used an electric downshift switch on the gas pedal.
The th400 I have is out of a Jeep Commando. I believe Jeep used the Buick 350 in commandos, trucks and full size Wagons. I think they called it the 350 rocket or something. As far as I know the 60's-70's Jeeps never used any auto tranny other than the turbo 400 until the 80's when they started using the Chyrsler 727, 999, and 904. It looks like a normal TH-400 cept for the two horns at the top of the bell. When I bought the transmission the guy tried to tell me it was a chevy 350 engine (and I told him I never saw a chevy with the distributer in the front like it should be). This motor is going to be used for pulling so I might be on the other side of the spectrum from most of the guys on here. I enjoyed reading through the posts ecspecially the kill stories. Wonder how a ricer would feel if he got dusted by a 6000 lb truck with 39" tires uzzled:
Since I know nothing about Jeeps this is all new to me. But the "rocket" designation usually refers to the Oldsmobile engines, kinda like how Buick used the "Wildcat" designation back in the 60's. Of course Pontiac, Buick and Olds all used 350's that, like the 455 s, didn't really have much in common.
I do believe he is correct about some Jeeps using bu350's, I dunno about the Rocket designation though
The M715's kick ass! They are basically Jeep one ton trucks, but have 1.25 ton off road rating capacity. They do need a bigger engine as the stock L6 is a gutless wonder, and I think the buick 455 you have is a good choice. You sound like you already have the 350 trans, I would probably suggest a turbo 400 if you were still looking, it is stronger and almost indestructible. Whereas the 350 has some weak links, especially behind a big block's torque. Many Jeeps did use a Buick 350 engine back in the later 60's. The Jeep term may have been rocket, but I agree that is normally used referring to Olds engines. Your 76 455 should have hardened seats and be low copmpression, probably fine for your application. If you want more performance, just talk to the mentioned supplier TA Performance. I have seen these M715's with all variety of engine swaps, from the usual small block Chevy, to big block Chevy's to Cadillac's. Any V-8 is an improvement over the stock engine. Why Kaiser ever put such a small engine with the rest of the overbuilt drivetrain and suspension is a good question.
I think for two reasons- 1. They didn't have to go fast. 2. They are geared all to hell and don't need a real torquey motor to go. well, three 3. The little L6 motor was probably easy to maintain and indestructable. Anyhow, the 455 is a great choice for this truck. You could keep it stock or go for an RV grind cam. Pretty much everything in a stock 455 would be perfect, just make sure the bottom end and oiling system are in good shape.
I picked the motor up yesterday and it was as promised. It also had a nice aftermarket HEI distributer on it (accel I believe). The transmission I have is definately a th400 not a th350. I will probably be letting the th400 thats behind the 455 go really cheap (like maybe a 6 pack of miller) if anyone lives in East TN and needs one. I got to figure out what stuff needs to be taken off (like cruise and EGR) and how to wire this beast now. Also I am going to have to figure out some hefty motor mounts. I plan to keep it pretty much stock until I see how it does (probably be way more motor than I need). Thanks for the help so far, I will probably pick your brains some more :grin: -Steve
