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390 to 429 swap

Started by Frozentoad, March 06, 2015, 07:00:05 PM

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Frozentoad

can anuone tell me if i can put a 390 in a 67 devill where a 429 was?will the exhaust manifolds from the 429 fit the 390 so i can use the same exhaust system?

Jason Edge

I am assuming this is a 1963 390 as the 1962 and earlier 390 is very different design. 

If you have a 63 390, this Help article on the 1963/64 Cadillac Website detailing differences in the engines and transmission from 1962 to 1965 will cover some of the items you will have to deal with when installing a Hydramatic 390 in a 1967 with that came with a Turbo Hydramatic 429 : http://6364cadillac.ning.com/profiles/blogs/enginesandtransmissions

It is definitely doable but you will have some things to address including different motor mounts, the difference in diameter between the THM flexplate (3") and HM crank end (3 3/16"), and various engine components such as exhaust manifolds, oil pan (63/64 were rear sump), front engine cover and water pump due to differences in radiator hose routing and probably a few other things the 67 guys can point out.  Personally I would hold out for the correct 429 block and rebuild if you have to.
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Frozentoad

thanks for the help.an dyou are right. i will stay with the 429 and rebuild it when i find a ne w timing cover

Scot Minesinger

I would stay with the 429 as you intend right now.  Swapping a different displacement engine lowers the value of the car and limits your future options.  If you did plan to switch engines a 472 might be better, as the 68 Cadillac used that engine, and transmissions were similar.  I think USA Parts 304-724-6600 has the 429 front engine covers.
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