1957 365 rebuild or replace?

[chelonian]

Hi Folks, I have the original drivetrain in my 57 Seville. Trans was rebuilt 3 years ago and has less than a thousand miles on it so i would like to either rebuild the old tired 365 or put in something else. If i keep the 365, can it be improved? I have done some other engines and they all benefitted from port matching, HEI, maybe a few other things. But i was wondering about different cams, bigger valves (if possible), more compression, anything to get it a good jump up from the 300 factory HP. New heads would be great too but i was not able to find anything aftermarket, like a Brodix head. It would be nice to get it up to 400hp or so.

Second option is to install a small block chevy or something else, but I would like to avoid the expense of a new tranny so the question is what engines would bolt up to the old hydro? Blueprint has a great looking 454 SMALL BLOCK that would physically fit and give me about 550hp. Just not sure about the tranny hookup.

Any help appreciated. Thank you.

[Joe Jensen]

You could install a 100hp NOS kit after you have your 365 engine rebuilt.  A NOS system isn't something I would install on a classic  Cadillac but it seems to be the easiest solution to addition HP.

If you do install it, please let us all know how well the engine and transmission hold up.

Good luck,
Joe

[Roger Zimmermann]

Most probably the original transmission could handle the 300 PS (or 220 SAE net)without issue but not much more.

[The Tassie Devil(le)]

I can only go from experience.

When I purchased my '60 CDV, it was fitted with a 454 BBC and TH400 Transmission.   It went okay, but always felt like something was wrong.

When I replaced it with an original 390 and Hydro, the car handled so much better, and the gearing of the transmission was beautifully in sync with the rear gearing, and being a 4 speed, it got off the line more smoothly than with the taller gearing of the TH400.

Plus, the added weight of the original engine and trans put increased weight on the front suspension, making the springs work correctly.   Made it drive like a Cadillac should.

With regards to rebuilding your original 365, I would be looking for a '59 through 62 390 which will bolt up to your trans.   The 1960 390 got a full-flow spin-on oil filter for ease in servicing.   The '61 and '62 have a 1" shallower sump, which requires the earlier starter motor to go with the block plate.

Bruce.

[dn010]

Anything can be improved with the right amount of $$$$$$. To start, you can get a cam for the 365, and put EFI on it. But personally, my rebuilt 365 uses a blaster coil, MSD box, Edelbrock 650 with 1" spacer and it moves my big 57 sedan deville pretty dam quickly when I floor it. However, this is not possible without a good tune-up and everything being adjusted properly.

[Warren Rauch #4286]

If you only have a 300 HP engine,you could add the dual carbs to make it a 325 HP.

 When you had the Transmission rebuilt is it to single or dual carb standards? The single carb trannys used serial number prefix CA,dual prefix CE.But what did the  rebuilder do?

Warren

[Roger Zimmermann]

If you only have a 300 HP engine,you could add the dual carbs to make it a 325 HP.

 When you had the Transmission rebuilt is it to single or dual carb standards? The single carb trannys used serial number prefix CA,dual prefix CE.But what did the  rebuilder do?

Warren

Warren, to add the dual carb set-up is a very bad idea. This is the most idiotic arrangement, but good looking.
Regular Cadillac models have the prefix "C". CA are used on 75 and CC series.
The changes regarding C, CA or CE are at the hard parts. For the rebuilder, this is not important, unless such an hard part must be replaced.

[chelonian]

You could install a 100hp NOS kit after you have your 365 engine rebuilt.  A NOS system isn't something I would install on a classic  Cadillac but it seems to be the easiest solution to addition HP.

If you do install it, please let us all know how well the engine and transmission hold up.

Good luck,
Joe

Thought about that Joe! YEars back i read about a guy who put 200 shot nitrous on 502s and raced them. Said he had over 100 runs and never an issue. the engines were bulletproof.

[chelonian]

If you only have a 300 HP engine,you could add the dual carbs to make it a 325 HP.

 When you had the Transmission rebuilt is it to single or dual carb standards? The single carb trannys used serial number prefix CA,dual prefix CE.But what did the  rebuilder do?

Warren

Not quite enough power for me but thank you for the tip Warren. I would probably try the Holley Sniper first and up the octane to get the same results, but better MPG. But hell yea, at a car show who doesnt love those dual carb and tripower setups!

[chelonian]

I can only go from experience.

When I purchased my '60 CDV, it was fitted with a 454 BBC and TH400 Transmission.  It went okay, but always felt like something was wrong.

When I replaced it with an original 390 and Hydro, the car handled so much better, and the gearing of the transmission was beautifully in sync with the rear gearing, and being a 4 speed, it got off the line more smoothly than with the taller gearing of the TH400.

Plus, the added weight of the original engine and trans put increased weight on the front suspension, making the springs work correctly.  Made it drive like a Cadillac should.

With regards to rebuilding your original 365, I would be looking for a '59 through 62 390 which will bolt up to your trans.  The 1960 390 got a full-flow spin-on oil filter for ease in servicing.  The '61 and '62 have a 1" shallower sump, which requires the earlier starter motor to go with the block plate.

Bruce.

Bruce, I think i have come full circle. I decided not to go with the blueprint motor and rebuild what i have. After reading your post you confirmed my fears that "it just didnt feel right". Its a caddy, it has to roll like a royal. BUT, that said, i like the 390 idea. Does that use the same motor mounts? ANd how tough is the original tranny? Can it handle 400hp? Seems to be some doubt amongst the cadillackists. Thanks to all for the help!

[jwwseville60]

EFI and higher octane wont give you more than a scant few extra hp.
The engine's pistons are set at their factory compression ratio, thus more octane will only help with preignition knock.

The 1960-62 390 swap plus the correct year hydramatic is the way to go.
You can do a 3-angle job, port the heads and use an Eddy carb with an upgraded cam.

My guess would be an extra 25-35 bhp.

[chelonian]

EFI and higher octane wont give you more than a scant few extra hp.
The engine's pistons are set at their factory compression ratio, thus more octane will only help with preignition knock.

The 1960-62 390 swap plus the correct year hydramatic is the way to go.
You can do a 3-angle job, port the heads and use an Eddy carb with an upgraded cam.

My guess would be an extra 25-35 bhp.

JohnW, thanks for the input. Im not looking at any one thing to get me to the promised land, so all input appreciated. I searched for better heads, they dont seem to exist. I have port matched two other engines so that would be done here for sure. I would advance my timing with the higher Octane, that has worked for me on other engines, some pretty significantly. The EFI dyno runs i have seen didnt seem to add any noticeable power, its more for efficiency I guess. Im leaning more towards using a 390 since it will bolt right in and gives another 7% displacement, that should get me another 20hp right there just having a bigger "air pump". And the 50k coil will allow for bigger plug gap, which combined with the advance should add some as well. And then there is the cam. Lots to think about!

[jwwseville60]

When the Resto shop rebuilt my 1960 390, we did a 3 angle and a mild port job. Factory cam/pistons, etc. With the original 3 deuces set up properly this Eldo coupe really moves. Id consider the factory 3-carbs, perhaps. Sounds really nice on full power.

Dyno results were 262 bhp SAE net.

[dn010]

You can always go .040 over on either engine for more too.