I apologize if this question has been asked before. I'm having a 455 built, but I'm still running my 350 2 barrel while it is being machined. I started thinking that while the engine is being built I could proactively be getting ready for the 455 by upgrading the radiator, picking up a fan shroud, rearend and of course the transmission. I know I can bolt the 455 to the TH350, but can you bolt the 350 to the TH400 and if so what are the specifics? I'm guess I would have to swap out the drive shaft, but are there any other gotchas I should know about or is this even possible? Thanks, Chris
Thanks. I read that you can bolt the 455 to the TH400, but i wasn't sure about the other way around (350 to TH400). I want to start getting ready for the engine, but possibly still enjoy the summer with the 350.
Unless you are going to race or install some really sticky tires I would see about freshening up the TH350 and run what you got. If your current setup has a 2pc (sleeved) driveshaft I'd get a new one made up though...
I have done many of those. The rear support needs to be 6 3/8" farther back for a short tail TH400, check out the mount and height. Get the right speedo gears for your TH400; if your speed is in error, measure the error and make allowance at this time. The shift linkage ought to work; adjust it for a right angle from the rod coming down to the arm into the trans, when in drive. I have always been able to put the shortest 400 yoke on my drive shaft and reuse it. Its close, check yours out. The 350 and 455 bell housings bolt up, but a 12" vs 13" torque converter mean you need 2 different sets of holes in the flex plate. Olds has both. A switch pitch TH400 is even better. Bruce Roe
Keep the 350 like Ken suggested run it till it pukes. The 350 72 GS I changed to a 455 still has the T350 in it going on 7 years now. Bob H.
I have a well built Th-350 in my car that has been putting up with a twin turbo 350 for years and year now...
