1950s Engine swap, LS, BBC, SBC, who has done it?

[chelonian]

I have a 57 Seville with a very tired 365 single 4bbl. Looking for more power. Who has swapped to a more modern mill? Im a big block chevy guy but the Seville isnt the kind of car i open the hood on at a car show so I am looking for basic driveability. Not a fan of all the LS wiring but the hood will largely stay shut. No haters!!!

[TJ Hopland]

Its been done but I don't think its very common likely for good reasons.  I don't know the 57's that well to know what you may run into as far as the basic fit and bolt in part.  I know a bit later you would run into oil pan issues that would require more custom work.

Anyone that has done an engine swap that didn't involve a well thought out and proven kit likely found out the hard way that the basic bolt it in part is usually by far the easy part.  Its everything else especially the seemingly little things that really suck up all the resources.  Things like various lines and wires not being in the correct spot.  You don't realize how long it takes to just move or extend a wire a short distance till you have to do it.  Also doing it right and making it look nice can take a lot of time too.

You then have things like are you gonna keep the transmission?  If so does someone or can you make an adapter?  Will it take the power you plan to put through it?   IF you are not gonna keep it how are you gonna deal with the shift pattern being completely different?  Its a little thing but yet a big thing to make it work right.

You then have differences in that the Cadilac engines tended to make their power down low and were geared for that and thats not how BBC's work so you are now looking at a different rear end?  Again I don't know 57 but Cadillac didn't usually share things like that with other makes so nothing else just bolts in.

Its not that any of that stuff can't be done, it certainly can be done but the question is do you have the resources to do it all?  Resources like time, money, skills and or friends or family with time money and skills you can use?  Then assuming you do get it done does it matter to you that you have likely added no resale value to the car and maybe even reduced its value?  Again it doesn't have to matter or have value to anyone but you and I'm not saying that if you were to spend $5k+ rebuilding the engine you have that that you would get that back either selling the car.

Not saying its a bad idea and you should not do it just throwing out some stuff that should be considered before taking on such a project. 

Are you still active in the BBC world?  IF so how is it?  I'm not super active in any of it anymore partially because those markets have really seemed to be falling off over the last several years.  Things like the LS engines and general lack of new people coming into the hobby seem to be major factors.  Also doesn't help that the quality of parts is complete crap so you can spend a lot and end up with nothing.  Last engine I built was almost 15 years ago and even back then I had an oil pump fail so I had to tear it down and replace all the bearings right away.  That added like another $1k to an already 3-4x what I had planned to spend on the project originally.   

[chelonian]

You are right on the money TJ. I have a BBC in my 1970 Monte Carlo and its bad ass at 550hp. They are still popular, but mostly with the do it yourself crowd, which is dwindling fast. You can get a dozen of them off Craigslist right now in most areas. BUT, i realize the LS world is here, like it or not. So I would lean towards that. But yea, fitment is huge. And so much detail, I'm not going into this naively. BUT, it has been done on old cadillacs. I have seen BBCs, LS, lots of stuff, even a damn diesel (which looked ridiculous IMO). And it would be with a trans. Not interested in keeping this slug of a tranny (that i just had rebuilt 500 miles ago). But I think its like the old question, How do you eat an elephant? One bite at a time. So its just a matter of figuring out the pieces. 

[TJ Hopland]

There still is a Modified Cadillac forum.  I haven't really followed it or participated for several years now and it looks like I'm not the only one. Just checked and last post was in July so not a lot of activity there anymore but maybe you could do some searching there and come up with some information?  Guess its another sign of the hobby declining.  It doesn't seem like that long ago that was a pretty active group with interesting projects going on.

https://www.modifiedcadillac.org/forum/index.php/board,1.0.html?PHPSESSID=aa74e1c755b0dbf8ce3910449a7dc9a3

[Cadillac Jack 82]

365 is a great engine and plenty fast.  Dont Chevy up your Cadillac...at least opt for another Cad engine...

[Cadman-iac]

  I've tried the modified forum but it doesn't seem to have much if any participation anymore.

 As for engine swaps, I'm still working out everything on my 56. I'm using a 69 472 and a turbo 400 transmission with a 72 rear axle assembly. Work has been slow due to other things popping up and getting in the way, but I am still anxious to get back to it.

 There's a lot to consider if you go this route. There's no blueprint, it's all up to your imagination.

 In my case, I already had the 472, and the original 365 was missing. I had a 390 that came with the car but was separate from it, and in unknown condition.

 There's a lot of things I had to change to get it in the car, and you may not want to risk doing it on your car.

 One thing that makes it difficult is how Cadillac designed the brake system for 56. It's the only year that the booster/master cylinder was remote mounted and it's hard to work around. I decided to go with a Hydro-boost and keep it in the same location as the original booster.

 I also replaced the original steering gear box with a newer one as the 56 is the first year they used that bolt pattern which became standard for all Saginaw gear boxes.  I did have to modify the pitman arm to clear the end of the box by stretching it I believe about half an inch and the idler arm to match so that the linkage was symmetrical. I didn't get pictures of the arms to document what I did, but I still have an original set to compare with when I get around to that.

 Keep us posted on your decision and progress. I at least would be very interested to see what you do. Good luck with your car.

 Rick

[jwwseville60]

472 and a TH400 is my choice as well.
BTW, my 1955 FW has the remote brake booster too.
The rebuild kits for the 472 are a worry. Beware the Chinese made parts.
Someone out there might have a factory NOS rebuild kit with the lower compression pistons. Plenty of torque on 87 octane.

https://www.youtube.com/watch?v=Qh_h5OUMKIE

An LS3 is a Cadillac motor too of course.

[TJ Hopland]

I think junk parts are a serious problem for any platform especially those that are well out of production in new vehicles. That could be where the LS has a bit of an advantage but even there I'm not sure how much stuff say in a 2020 engine is compatible with the first gen like a 2001?   I saw a teardown of I think a 2020 ish LS and it was barely recognizable as a pushrod V8. 

[Mike Baillargeon #15848]

365 is a great engine and plenty fast.  Dont Chevy up your Cadillac...at least opt for another Cad engine...

If it were my choice I'd stay with a good running 365....The money and aggravation saved by not doing the Chevy swap could be used to put on a tri-power intake and carbs...

That would be plenty of power to pull that Seville around.....Good Luck with the project !

Mike

[35-709]

Would have to be cheaper, easier, and quicker to rebuild the 365, I would think.  As Mike Baillargeon points out, a tri-power setup should give it a nice boost and the engine could be warmed up a bit as part of the rebuild process.  An LS might be a Cadillac engine these days, but it never was back then.  A '62 390 might be a reasonable consideration also.  Not necessarily against swaps (I have a 472 in my '35), but would always rather keep my Cadillac all Cadillac.

[jwwseville60]

3.0 Duramax 6 cyl diesel?
It was used in Escalades from 2021-2024.

Also, the Chevy LT-1 was used in Fleetwoods during the 1990s.

[Big Fins]

You all are getting away from what the original poster posted for his question. He has a 1957 car. If he wants to do all of that work for the small amount of performance gained, that's on him. The swap questions are as old as this board. It's proven that the car was designed to operate with a Cadillac era engine. Putting in a Chevy/Olds/Pontiac engine throws off the entire car.

Someone mentioned a '62, 390. That would fit right in there in place of the 365. A dual quad manifold and carbs would give him all he needs if he wants ride around with his foot in it all the time.

People say it's because parts are unavailable. Not so. It shocked me as to how many internals were Chevy parts on my 390. Same part numbers as 283/327/305 engines from the 60's and early 70's.

[bcroe]

I would ask, what is wrong with the original
engine? Instead of looking for some silver bullet
cure all, I would first determine, what is wrong
with the original?  Could be as simple as a new
timing chain set and distributor.  If the original
engine cannot be brought to an acceptable level
of performance, a compatable 390 would be by far
the easiest path.  However, any rebuild here has
hardened valve seats and low enough compression
to run on the cheap unleaded. good luck, Bruce Roe

[dn010]

I know to each their own when it comes to their cars and their desires, but here are just some thoughts from another 1957/365 owner:

I have a sedan deville and the 365 moves the car pretty quickly. Of course, the engine is rebuilt. I have a Edelbrock 650 on it with electric fuel pump. There was a point in time that I wanted to put a cam in it (they are still available) and replace the 650 with a sniper, but after some time I did not see the point. The 365 has started, gotten me to where I needed to go and back every time. There was a time before rebuild where it ran crappy, had no motivation to get off the line as quickly but it is amazing the difference a tune-up can do.

You can dump tens of thousands of dollars into these cars to put the biggest engine in it but it's still a heavy old car that will sit there burning the tires off before it actually gets going. Then when it actually gets going, you need to figure out how to stop it faster and how to stop the cloud float it will do above 60mph. So after you've bought your LS engine and rebuilt that (because what's the point in putting a junk yard engine in a car without freshening it up), you bought the transmission that will go with it and possibly rebuilt that as well, got your custom driveshaft, custom transmission and motor mounts and any other braces or brackets or part required to hold the engine to the frame which will ultimately need to be cut and modified, you'll need to figure out engine fuel/air management, your exhaust system, disk brakes along with all the hydraulics behind them and also a new suspension since these cars don't handle at all at high speed. You'll need to figure out how to adapt to the power steering and a/c among other things. Hopefully your 67 year old differential will handle the increase stress. This is just a basic list, there is much more that is involved.

Personally the benefits outweigh the cost, fabricating and time involved to swap an engine into these particular cars. When you go to sell it, don't expect to recover the money you spent.

If it was a car with an engine that was not great to begin with, like, say, the DeLorean... then I could see how you'd justify doing a swap. (I did a swap on mine).

[Cadman-iac]

If it were my choice I'd stay with a good running 365....The money and aggravation saved by not doing the Chevy swap could be used to put on a tri-power intake and carbs...

That would be plenty of power to pull that Seville around.....Good Luck with the project !

Mike

Did Cadillac ever use a tri-power setup? I've only ever heard of the dual quads before.

 Rick

[Cadman-iac]

Would have to be cheaper, easier, and quicker to rebuild the 365, I would think.  As Mike Baillargeon points out, a tri-power setup should give it a nice boost and the engine could be warmed up a bit as part of the rebuild process.  An LS might be a Cadillac engine these days, but it never was back then.  A '62 390 might be a reasonable consideration also.  Not necessarily against swaps (I have a 472 in my '35), but would always rather keep my Cadillac all Cadillac.

 Someone had used a 390 in mine before I got it, but then they tried installing a 350 small block and a 700R4 before giving up and selling it to me.
 I got the 390 and the original transmission separately, and for years I thought I had the original 365. It wasn't until I checked the block for numbers that I realized it was a 390.
 Regardless, it wasn't in good shape, and I already had a rebuilt 472, thus the decision to use it. I wanted more power but I wanted to keep it all Cadillac. The 472 and the 500 cannot be mistaken for anything other than a Cadillac, unlike the LS even if it did come out of a newer Cadillac.
 Yes, if I had the money I would just go with the 365.


 Rick

[Cadman-iac]

3.0 Duramax 6 cyl diesel?
It was used in Escalades from 2021-2024.

  Just....NO!!!! Lol!!

[Big Fins]

Did Cadillac ever use a tri-power setup? I've only ever heard of the dual quads before.

 Rick

Yes. The "Q" code engines were tri-power. They came along in I believe 1959. It added 20 BHP to the engine.

[Roger Zimmermann]

Yes. The "Q" code engines were tri-power. They came along in I believe 1959. It added 20 BHP to the engine.

Also used on 1958 models; standard on the Brougham, Biarritz and Seville. Optional on the other models.

[Cadman-iac]

Yes. The "Q" code engines were tri-power. They came along in I believe 1959. It added 20 BHP to the engine.

 That's right, I had completely forgot about those. Thanks,  Rick