Trivia question: Why did the redesigned engine for 1963 stay at 390 cubes...

...and then the next year, in 1964, get enlarged to 429?

I would've thought that with Cadillac's going to the time, trouble and expense of re-engineering the old 331-390 engine into the next gen, they would've wanted to come right out of the box as a 429. 

Doing a one-year-only new gen 390 with the same hp and torque figures as the old engine, seems like a waste of effort. 

My only guess as to why it stayed at 390 cubes is that perhaps the Turbo 400 transmission wasn't ready yet in '63, and the 4-speed Hydra-matic couldn't handle the torque of the 429.

Any truth to this? 

Thoughts?  Information?  Guesses? 

Views: 135

Reply to This

Replies to This Discussion

The 64 Series 62, 75 and commercial chassis used the Hydramatic, so that can't be the reason. Not sure what it is though.

Good point indeed!   I'd overlooked that.   

Deepens the mystery even more. 

1962 & 1963 Cadillac Serviceman October issue might give a hint. At least partly.

I checked out the '63 and '64 Serviceman reports, and other than details of the new 390 engine for '63, I didn't see where it explained why the displacement, hp and torque were left the same as in the old-gen 390 instead of just going straight to the 429 they they knew was coming out in '64.  

As you know, engine programs call for planning years in advance of production, and so when the '63 390 was being designed, they already were aware of wanting to enlarge it to 429.

My question stands:  Why did Cadillac produce a one-year-only new-generation 390?  Seems like a lot of added cost and complexity, to do it that way. 

IMO: When engineering a new engine, don't hide that fact (and the advertising value) by using the same displacement and output as the engine it's replacing.

For those that have read about the new for 63 390 you know there were very significant changes made from the 62 390 - 52 lbs lighter, shorter block, different crank, distributor and other components brought to front of engine, etc.  Also, while the 1962 and 1963 390 blocks were very different, they used the same cylinder heads.  With the 429 displacement and wider bore the heads had to be redesigned. You also have to consider that the Cadillac 390/429 is actually about the same size, maybe a tad bigger, than a small block Chevy, and they had to do some creative redesign to get that 4.13” bore. For example that reduction in head bolt size from 7/16” to the very odd 13/32” had to be to gain a bit more clearance for the thinner block walls. Also, keep in mind that by 1963/64 Cadillac was deep into development of the new V-12 that never made it to production. As I recall six V-12’s prototypes were built in 1963 and 1964.

So there was a lot going on and my guess is they decided to modernize the 390 as both a selling point and real improvement but also to buy time for continued development of the V-12.  As far as the 1964 and later 429, I’m also guessing there were external factors pushing Cadillac to produce bigger torque and horsepower numbers, until they could get the 472 in production in 1968.  For me the odd head bolt size has always made me think the 429 was a stopgap to keep up and ahead, but as we all know the 429 went on to be used for 4 years!  
A lot of things like mounting a Buick transmission on a 1964 429 with an adapter ring, selling 1965 Series 65’s that look just like a 1964, or introducing a new for 1963 390 with the same specs as the year before May all seem odd now, but it was usually because of timing… or the lack of!

For more on that V-12 that never was, here is one article https://macsmotorcitygarage.com/a-cadillac-v12-that-never-was/

RSS

Photos

  • Add Photos
  • View All

Forum

cornering lights

Started by Larry Rees in 1963/64 Cadillac Specific Discussion. Last reply by Jason Edge 3 hours ago. 6 Replies

Neither of my cornering lights are working. I started by focusing on drivers side. I removed the entire assembly and cleaned it up, replaced the wire to the socket, cleaned and lubricated the socket…Continue

Power Steering Hose Questions

Started by C. Van Tune in 1963/64 Cadillac Specific Discussion. Last reply by Russ Austin 6 hours ago. 1 Reply

My '64 Eldo's high-pressure P/S hose sprung a leak, so I want to change it (and the low-pressure hose.) My car is concours-level restored, so keeping as close to the stock fitment and appearance is…Continue

Pertronix 3 install and resistor wire

Started by Dave Fehrle in 1963/64 Cadillac Specific Discussion. Last reply by Dave Fehrle 20 hours ago. 17 Replies

A few questions on the resistor wire, what color is it in the pic? The yellow/blue or black? And connecting to the ACC on the fuse box seems easiest way to go with the new switched wire, but where…Continue

63 Exhaust Hanger Mystery

Started by Mike Travers in 1963/64 Cadillac Specific Discussion yesterday. 0 Replies

I'm in the process of installing a stainless steel single exhaust from Classic Exhaust on my '63 Coupe de Ville. I'm running into a mystery regarding my middle exhaust bracket. I have the bracket…Continue

Blog Posts

accumulator dryer

Posted by CHRIS CARLSON on December 6, 2023 at 10:54am 0 Comments

Who rebuilds original AC  accumulator dryers for 1964 Cadillac? I have been on Classic auto air in Tampa FL wait list for over a year ,  There is one on Old air products web site that looks very similar to the original # 21-4214A but states it fits 1962 Gm cars, The one recommended for a 1964 Cadillac is half the length 21-4215A    What  is everyone using ? I would prefer to be as original as possible. Thanks

'63 Eldorado trumpet horn + 2 standard horns restoration

Posted by Les Eastling on November 15, 2023 at 10:34am 1 Comment

My son, unbeknownst to me, had all three of the horns on our 1963 Eldorado completely restored. We had recently added the Eldorado trumpet horn to the two standard horns and the sound was not very good... we had heard good ones so we knew something was not right... but there was not much we could do to get better sound from the 3 horns. 

There is a restoration service called The Horn Works who my son…

Continue

Clock ‘64 DeVille

Posted by Matt Vander Hooven on July 23, 2023 at 7:36pm 2 Comments

Is there still a member in the Detroit area that refurbishes clocks?

Matt VH

Spark Plug Heat Range

Posted by Patrick Westphal on July 7, 2023 at 10:00am 1 Comment

I found a diagram that illustrates the main factor in determining a spark plug heat range that I was trying to describe to you during the chapter get together.

Here it is:

 

The main factor is the length of the ceramic insulator from the middle of the spark plug to the tip (where the spark happens)  

The insulator…

Continue

Videos

  • Add Videos
  • View All

© 2024   Created by Jason Edge.   Powered by

Badges  |  Report an Issue  |  Terms of Service