What is involved in mating a 62-401 nailhead to a TH400 trans? Here in Oz most people just heave the nailhead and Dynaflow trans and fit the usual 350/350 combo cos its cheap and easy to maintain. Buicks were pretty rare out here and nobody knows much about the engines and transmissions which is how I got a recoed 401 with a rooted Dynaflow trans. I did a search and 34cpe5w had a 401 with TH400 for sale which came out of a 67. Would that TH400 be the same as a Chev pattern version? Would the 401 flexplate bolt straight up, starter position be OK, etc? Thanx for any help, swifty
The TH400 you want is either a ST400 or a SP400 out of a 64-66 Buick with a Nailhead. The Chevy will not work without an adapter. If you search there are a few threads on it here...
64-66 Buicks came with the 401/425 and a ST400, which is a switch-pitch converter 400. Unfortunately the bellhousing pattern is unique to nailheads, nothing but a "round bell" 400 will fit. BOP and Chebby 400's will have to have an adapter. Also, there's differences between the crankshafts on a 'flow nail and a 400 nail. Pilot hole on a dyna crank is larger in diameter, there are adapters to help with that. You'll need the flywheel from a 400-equipped motor as well, and the center hole will have to be opened up to allow it to fit properly. I'm not sure if you'll have to space your starter out or not. You might be able to get lucky and use a 64-66 starter. I know on 57-60 blocks there's a hole to drill and tap to allow use of the later starter, but I'm not sure on 62 blocks.
Any idea on the dimensions of the pilot bushing so a guy will know what he has? Did they quit using the Dynaflows by 64? That's what my block is.
ST400 is the non Switch version... the SP400 is the Switch Pitch version.... Not all of them had switch pitch, as a matter of fact the majority did not...
I can't remember the dimensions off the top of my head, the last one I got I actually got from Carmen Faso when I was ordering a bunch of parts.... I ended up giving it to Stevie G, maybe he can measure it if it's not in a car yet...
Just FYI.... A source for TH400 trannys: wanted to give everyone a heads up on a good place to look for TH400 transmissions. keep an eye out for jeep pick-ups and wagoneers 1965 to 1972. they have the same bell housing as a 401 nailhead and are th400's. you can unbolt the transfer case adapter and bolt on a 4" tailhousing and your ready to go! the holander number is # 1331, so start looking. i had never seen one till today and stumbled across one. Also Rolls and Bentley you are correct about this trans bolting up to a nailhead, but the output shaft should be a course spline on the jeep & about 3.75" longer than a 2x2. Dave the one i found was out of a 1970 jeep p/u but the output shaft is the same length and spline as my 65 buick trans st400 i have! what do you think the deal is with that! maybe it was changed or something. Yea, sounds like someone changed the shaft to be able to use a later GM transfer case. Good deal for you tho. Just checked on the jeep cores I have & they both have the long course spline output shafts. But you will want to overhaul it anyway, so thats the time to switch shafts.I got tons of the 2x2 shafts if you need some. Dave Most of the nailhead cases in Jeeps have the fine spline short shaft used with the 4" extension housing for Buicks. the exception being the Quadratrac transfer cases. You can also find them in CJ7's until 1980. Even stranger, the Jeeps with a 350 Buick in them used the Nailhead case, with an adapter to bolt to the 350. this is the adapter that might be reversed and used to fit a BOP stick housing to a nailhead. Don't know that it would work, never tried it, May be impossible, I really don't know. The guts will interchange from any T400 to any other T400 case. there are differences. The Buick valve body will hold the trans in the gear selected, and not "blow" shift like a chevy T400.The ST400 parts will fit too, with qualifications. you have to use the ST pump with the ST convertor, and the is an orfice plug that has to go in an oil passage behind the pump at the top of the case. Also, you can use a ST 300 convertor in a ST 400 to get more stall out of the trans. The ST 400 convertor is 13", the ST 300 convertor is 11"
Hey thanx for all the replies and info even though it's not what I wanted to hear! Sounds like I am going to need a bell-housing and pilot bushing adapter and possibly a 64-66 starter cos I will have no hope of finding a ST400 or SP400 trans out here. Buicks just don't exist in wrecking yards. Who makes or supplies the adapters mentioned, I found a list of contacts for nailhead parts so should I start there? zman, the jeep pick-ups and wagoneers are probably rarer than Buicks out here so unfortunately that wont help me plus you need the Buick extension to add to it. Thanx for that info tho. Where did you find that cos I spent all last night reading posts on nailheads and didn't see that? Your name and lots of other familiar ones kept popping up tho.
I apologize for my naming error. Zman's previous post looks like a subject on the yahoo nailhead forum, in condensed form. Have you checked over there? Might find someone close with something you can use.
It's actually a cut and paste from an old thread that I saved... It's easy to get confused, I hope I didn't come off as an ass, though it wouldn't be the first time if I did..
Call Carmen Faso in Tonawanda New York... (716) 693-4090.... He'll have the parts or povide the informtion you require... He's the nailhead guru and a excellent guy to deal with !!!!
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