Questions on Super Turbin 400 on my 401

[old28]

This is the first time that I have been on this site. I have spent the last 4 hours going over threads on 401 Nailhead motors and some on the Trans.

To give you a little background, I just purchased a 1929 Ford RPU project with a 401 motor. The block casting # indicate that it's a 61-66 block with 59-66 heads. The trans that came with the setup appears to be a one year only model that was built for the 1966 401 nailhead. The best I can put togeather from this site is that it is a "Super Turbin 400" that has a case that is round at the top, unlike the later TH400 that have a saddle at the top.

I have attached a few pic's of the trans. The case at the top has a 6" crack in the alum and I have no idea on the inside condition.

Question? Will any of the later BOPC trans bolt up to the block? What do you have to change? Are there any of these old ST400 that are rebuilt and can be purchased?

This is one real nice site with a lot of information. I have been building drag race BBC motors for our cars for the last 30 years. This 401 Nailhead is the motor I always wanted to build and put in a RPU and at 65 I'm going to get a chance.

Any help or ideas on the trans situation will be helpfull.

Thanks, Tom

[old28]

Missed the pictures, hope the come through this time.

[BigRivy]

The later transmissions will obviously not bolt up without an adapter of some sort. The early cases like you have should have almost the same availability as the Nailhead engines that they were behind as most Buicks had automatics. Any tranny shop that can do a later model TH400 aught to be able to overhaul that one without too much trouble. There are some differences in the early ones but nothing too drastic. If you have trouble finding a replacement you could probably have yours welded if its not in too critical of an area. The pictures you provided are not real clear on where the crack is. If it's in the center of the top of the bell housing I think welding would be a viable option, provided someone in your area can do a decent job with a welder. I ran a TH 400 behind a a 455 for years that had one of the lower mounting holes below the dowel welded back on.

[old28]

Thanks for the information. I have little to no experience with TH400 type trans. I have used PG on all my race cars.

The crack is from the top center and runs down towards the rear about 6". I'm sure it can be welded if needed. Because the location of the crack is not in a critical area and is on the open part of the bell housing I might be able to drill a hole at the end of the crack and JB Weld it up.

Do you know if anyone or company that has rebuilt ones for sale?

[nailheadnut]

Look on the passenger's side of the transmission and find the data plate. There will be a date and model number stamped on it, most likely a BT. There were two kinds of ST400's that came behind a nailhead. In '64, a one year only model, the transmission is like any other 3 speed automatic from the TH400 family. The kickdown is electronically controlled and there's a one prong sender on the driver's side of the transmission to control it. The 65 and 66 transmissions were equipped with a dual position torque converter, commonly called a switch pitch converter because the pitch of the vanes in the converter is controlled electronically. If the sender on the driver's side is a two prong unit, then the trans is a 65/66 model. The same innards were in the '67 ST400, but they were now housed in the saddle backed bellhousing style trans. After 67, the switch pitch was dropped.

Open google in your browser and enter "ST400 switch pitch" and you'll probably find a lot of info on it.

You can determine the exact year and hp rating of the engine by locating a two letter code on the top surface of the block, passenger side, right in front of the valley cover. T = 401, W = 425. J = 63, K=64, L=65, and M=66. Therefore a MT would be a '66 401. A KW would be a '64 425.

This site has a ton of information in the Shop link. Lots of pictures and data.

Here's the link that shows where to find the engine code

http://www.teambuick.com/forums/view...t_engine_where

Here's the link that shows the transmission codes.

http://teambuick.com/reference/auto_400_codes.php

Ed

[old28]

Ed,

Thank you very much for all the information. I will check the code and see what I have. You guys are great. I always wanted to to build a 28-29 RPU with a nailhead in it and my time has finally come. This is all new for a BBC/PG guy to get hold of, but with your guys help I know I will get through it.

Thanks again, Tom