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Will TH400 bolt to a 390 block?

Started by Mike D #19390, March 07, 2005, 05:10:58 PM

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Mike D #19390

Anyone happen to be familar with trans bolt patterns?

Question - will a standard BOPC pattern TH400 (probably 1968 and on to avoid switch pitch trans) bolt up to the earlier 390 or 429 blocks?  Specifically, want to replace the Jetaway in a 1960 with 390 engine with a TH400. Also have a 64 with a 429 that has the early TH400 trans, but would like to replace it with a later year.

(Reason for avoiding the switch pitchs is theyre real expensive to rebuilt vs. a standard TH400.  Also easier to grab a std TH400 from a junkyard.)

Mike #19861


 The THM400 will bolt to the 429s from the 1964 deVille and Fleetwoods, not the 62s or 75s. They will bolt to the 1965-67 429s. The THM400 will not bolt to any 390s.

  Mike

Doug Houston

I did that once, and heres what I know. The 390 went through 1963, and became the 429 in 1964.

I had a 63 CdV that I wanted to have a THM400 transmission in. I bought a 65 engine and transmission from a salvage car. The transmission had a different length tail shaft/housing, so I had to get those pieces from another transmission. That worked O.K. Once the proper trans. was on the engine, I lowered it into the chassis. WHOOPS!  The mounting ears on the 65 engine (a 429, of course), were either forward or rearward (Ive forgotten) from the mounting holes in the 63. So, I had to elongate the holes to accomodate the 65 angine, and it finally went in. The bell housing was a tad too  close to the firewall, so on heavy acceleration, the engine would hit the body. It was a wonderful car to drive, and I put about 20K miles on it. However, it wasnt a good conversion. That was around 1969, when who ever cared what youd do to a junmker of a 63. Its different now.

NOW, heres what I should have done: Use a 64 429 engine and the TYM400, as it was done on the 64. The engine mounts were in the right place. Part of your original question: the THM400 wont bolt to the 64 engine. The Jetaway was used in the 1965 series 75 cars, and had some sort of adapter plate to put a Jetaway on a 429 engine.

Mike #19861


 From what I understand, and I am remembering this from a past thread on another site, is the block and crank were differant on the 429s that used the THM400 and the ones that used the Hydra-Matic. Only the deVilles and Fleetwoods used the THM400 in 64. The 62 and 75 Series cars still used the Hydra-Matic.

 The Cadillacs for 1965 were all new, and I would expect some changes may have been made to the powertrains because of that. They remained similar through 67 (but the 67 429s had their own unique qualities) and you cannot put a 472 in a 67 without some major modifications, even though the cars look almost identical.

 The 1963 390 was unique from all the 390s that came before, and actually had more in common to the 429. The engine was re engineered for 1963 and employed the new thin wall casting techniques and the accessoory drive was changed to an aluminum front cover. The distributor and oil pump locations were moved to the front of the engine as well. This lightened the engine considerably, but basic specifications did not change, such as bore and stroke and power output.

  Mike

Ben H.

Lemme see if I am learning this correctly.

I have a 63 commercial chassis. If I want to put in a trans from a 64 I need to use one from a Ser. 75 and not a Fleetwood?

I found both a 64 Series 75 and a Fleetwood at a pick n pull. I need to know what I should grab from either car. Both are really picked apart, and the engine is already gone from the Fleetwood.



Warren Rauch

 Why don't you ask something easy ,like what the stock market is going to do today? The answer to a 68 or newer trans. in a 60 is most likely no.
  There is a lot of wrong information on avalible ,so I hope I get this right. The 1959-62 390 engine was replaced in 1963 with a reworked lighter version. ( the cylinder head from 63 fits back) This engine was enlarged in 64 to 429. The 64 (&6575)block is all by itself as the 65 exc 75 block had new engine mounts for the new frame and a change in trans. mounting.The cranks were different for turbo trans and Jetaway (hydromatic) this meant different part numbers that year.To make the turbo work on the same block an adapter was used for 64 ,and 65series 75.The adapter was dropped for the other 65 models and newer by changing the engine casting.
The transmissions were changed almost annually and the series 75and CC were not the same as the lighter models.In 64 both turbo (60s andDeVille) and Jetaway (series 62 and75)were used. As metioned above they used a different crank and a block adapter on the turbo models.In 1965 the series 75 used a modified 64 turbo .The adapters were gone on the other models
The flywheels fit 61-64with jetaway; 64 and 6575 turbo; 65 exc 75 and 66-67.The cranks are the same 59-62;63;64jetaway;64turbo&65 all;66-67. THe 472 in 1968 was a new engine and almost nothing works back.Warren