Are 65-67 Cadillac switch pitch 400's BOP pattern

Are the Turbo 400 transmissions (which used a switch pitch converter) used on 65-67 Cadillacs a BOP bell housing pattern?
If so were they designated with a different model number?
Buick designated their 400's SP400'S.

 

I know they used them in Buick's and Cad's so I would say yes!

 

Sorry the answer is NO!

That tranny only fits those years. But all the internals will fit into any other TH-400.

Mike

 

So if they are not BOP pattern, then what are they? Are they nailhead pattern or something? I know Cadillacs did indeed use SP tranny, but would they change over to some odd housing pattern for 64-67, then go to BOP? Hmmm?

 

They were an odd caddy pattern, not the same as the earlier ones, not the same as the later ones.

Do you need a trans, or what?

 

Cadillac THM400 bellhousings were initially unique:
'64 Cadillac has an even radius top flange, the 'round top'. This case also fits ONLY the '64-66 Buick TH400s behind the 400, 401 & 425.
For '65-67 Cadillac has a unique TH400 bellhousing with a flat section on the top ('flat-top') - fits nothing else.
Finally, the 'twin-eared' bellhousing fits all Olds, all Pontiacs, Cadillacs '68 and later, and 300 & 340 Buicks.
This info comes from Ron Session's book 'How to Work With and Modify the Turbo HydraMatic 400'- a great reference that also includes all THM400 codes and what it came out of.

 

Thanks for the information, especially the book info. One other thing, Oldsmobile used an SP type 400 from 65-67. Does that mean that those blocks were unique too?

 

Seems to me that Olds was the same as Pontiac back then....at least the Olds switch pitch TH400 transmissions I've had all look like typical newer BOP cases.

 

The 'twin-ear' case TH400 fits the '65-67 Olds, and all '68 & later Olds. Cases via pics clearly do not interchange: '65-67 Olds' blocks must've had the same bolt pattern as the later blocks, since Olds' only used the 1 THM case design (with different internals).

 

D2W,

The pattern is the same as early 365 and 390 engines ! The bolt holes are smaller though ! I have a 62 390 adapted to a 1965 Cadillac SP 400 ! I had the Crankshaft machined to fit the 65-67 flywheel/flexplate ! The pilot bearing hole in the crank was enlarged slightly to accept the SP torque converter ! Studs were made to fit the larger holes in the bellhousing and the smaller holes in the transmission case ! The starter had to be moved to clear the Oil Filter Housing ! I plan to check an aftermarket high torque starter to see if it clears the oil filter better ! I hope that the aftermarket starter will fit the flywheel cover better ! The 65-67 flywheel covers are aluminum ! I have check the fit of everything , but have not reassembled the engine after a rebuild !

Good Luck,
Sonny

 

I tried to put a 66 Cad TH400 case on the back of a 58 365, it didn't quite line up, I think the dowels were off by 1/4" or something.

They look the same...but don't fit the same....so make sure you have your ducks in a row before you try to put a th400 on an early cad motor. Might want to do a bit of research.

 

Squirrel,

I knocked the Dowel Pins in ! I do not remember if they were off or just too large ! I will have to look to refresh my memory !

I am not the first to do this conversion !

Good Luck,
Sonny

 

Did you just run it without dowels?

 

Sonny, Squirrel: Thanks for the information on adapting a Cad Th400 SP tranny to early Cads. I plan on purchasing the book on turbo 400s. One question I had involved the Olds SP Turbo 400's, used from 65-67. I am under the impression that the newer Olds engines (POST 394'S) used the BOP pattern. If this is the case, then wouldn't the Olds SP Turbo 400 be a BOP pattern?

I wanted to bolt a SP Turbo 400 to a Buick 300 cid engine, which does have BOP pattern.

Comments welcome!

 

Squirrel,D2W,

I have not done anything about the Dowel Pins as yet ! All other bolt holes are the same , just smaller on the later transmission ! The engine is still disassembled !

I am not familiar with all GM 400 Transmissions ! I know that the Cadillac pattern changed to the BOP pattern for 1968 models ! I believe that Pontiac did the same !

Buick used the SP Transmission starting in 1964 ! The Transmission interchanged with the 1964 Cadillac ! The 64 Trans. used an adapter ! The 64 Transmissions have some different parts and shift pattern and are not recommended !

Good Luck,
Sonny

 

As far as I know, the 65-57 Olds SP th400 will fit a Buick 300 engine, it's the standard later BOP pattern.

Also you can put the SP guts in any pre-1980ish TH400 case, just need to put an orifice in the passage (some late 70s cases are not drilled, and 1980s cases don't have the casting for the SP oil passage). Caddy used the TH400 into the early 80s, chevy trucks thru 1990 or so.


Sonny--if it were me, I'd maybe put the bare trans case on the engine block, with the crank in the block, and dial indicate the pump opening in the trans case with the indicater mounted to the end of the crank, to make sure the trans is concentric. But that's just me. Maybe it works fine!

 

Unfortunately no they are not std. BOP

Sorry.There is and adaptor available www.cad500parts.com has them in their oldies but goodies section I believe.

Sent from my SM-G930R4 using The H.A.M.B. mobile app

 

Given all the preceding discussion of what is, and what isn't BOP, I think your post is too brief to make clear what you mean.

If you are answering the OP's question, post #1, confirming the '65/'67 Caddy trans IS NOT BOP then I believe you are correct. But the discussion shifted to '65/'67 Olds patterns and your reply, absent clarification, could be construed to apply to the Olds eng/trans patterns.

I believe all post 394" Olds V8 engines, 307/330/350/400/403/425/455 use what is commonly called the BOP pattern. Same for Buick 225/231/252 rear drive V6, 300/340/350/400/430/455 v8 and a bunch of Pontiacs and '68 and later Cad.

Ray

 

I have a SP TH 400 out of a 67 Buick if you need one.