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1941 engine swap: will 1941 hydramatic tranny fit an engine with 3-speed manual?

Started by smstalter, June 04, 2014, 09:04:58 AM

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smstalter

Hello folks,

This is my first post here, so forgive me if this is a silly question, but after a short search, I couldn't find the answer, so here goes:

My dad has a 1941 Cadillac 61 Series 2-door fastback sedanette with a hydramatic transmission. Unfortunately, the original block is cracked and cylinders have already been bored out to maximum, so we located a donor 346 L-head V8 engine for it.

But the concern I have is whether the hydramatic transmission we originally had on the car will fit this new engine (which came from a car with a 3-speed manual (?) transmission)?

Also, I noticed that some 1941 owners have swapped out the 1941 hydramatic and replaced it with a 1951 hydramatic (improved reverse mechanism) or, in some cases, just went to a manual transmission.

I'm open to ideas on this, because I'm kind of in a position to go either way depending on which is the better option (we don't have the engine in hand yet, and I'd like to settle this question before we do). I kind of like the idea of installing a 1951 hydramatic transmission to replace the 1941 hydramatic, but where would I find a 1951 transmission and at what cost?

Any ideas?

Thanks in advance!

Brett Baird

It will, but the alignment dowels on the back of the engine block where it mates to the bell housing are different between manuals and automatics. It simply requires you to remove the incorrect  dowels from the new engine, and install the correct dowels from the old one.
B Baird
17764
'41 Fleetwood 60 S  http://bit.ly/1jwgEWm
'59 Sedan DeVille 6339 "Flat-top"  http://bit.ly/1jwgUF1

Martin Michaels

Call Eddie Jones,I bought my '51 transmission from him when I swapped out my '47. See his ads in Hemmings.
Marty  CLC#26833
1947 6269  Cavern Green
1980 CDV D Elegance  White

joeceretti

Seems to me the biggest problem with swapping out the hydramatic for a manual will be the shifter linkages. I am far from an expert in this regard though.

I like my 3 speed manual.

Keeping the existing transmission is probably the easiest and least costly option. It will fit.

smstalter

Wow! Thanks so much for the input, guys! I really appreciate it.

The original transmission on our car is the hydramatic, so if I understood correctly, the hydramatic transmission we have should fit onto this donor engine (which came from a car with a 3-speed transmission) without too much difficulty, is that right? It's essentially a question of correctly lining up the mounting dowels? If so, that's really great news!

I'm still thinking that picking up a '51 hydramatic might be a good option for upgrading the hydramatic we have, so I think I'll contact Eddie Jones or Ed Cholakian about that.

Thanks again for your input!

Brett Baird

Yes, the trans will attach to the donor engine.  But it isn't a matter of lining up the dowels, it is a matter of changing the dowels from the original engine to the donor engine.  The hydromatic dowels are a different size and located in different casting holes - at least they were on the '46 hydromatic donor engine that I swapped into a manual '41.
B Baird
17764
'41 Fleetwood 60 S  http://bit.ly/1jwgEWm
'59 Sedan DeVille 6339 "Flat-top"  http://bit.ly/1jwgUF1

smstalter

Does anyone know whether a 1951-55 Cadillac hydramatic transmission will fit a 1941 Cadillac 346 L-Head V8 engine that originally had a 3-speed manual transmission attached to it?

I'd sure appreciate it if you can let me know.

Thanks!

jackworstell

......I've been told that for 1941 ( and maybe for 1942 )  that the blocks came drilled EITHER for alignment dowels for the manual OR for alignment pins for the Hydramatic.     I believe that starting with 1946 ( or for 1942 ) blocks were drilled for either set of alignment pins.

     I think it would be tough to drill a block for a set of missing holes for the alternate alignment pins.......they have to be just right.

     I've heard a suggestion that in a case like this...just pull the existing alignment and go without any.  But this seems iffy to me...

     Doug Houston or Jack Hoffman will probably know more.

Jack Worstell       #7558

Brett Baird

Jack is correct - 41 blocks are not drilled for both type of transmission alignment dowels.  They are drilled for one or the other.
B Baird
17764
'41 Fleetwood 60 S  http://bit.ly/1jwgEWm
'59 Sedan DeVille 6339 "Flat-top"  http://bit.ly/1jwgUF1