Technical 331 Cadillac engine build , looking for insight

I recently decided to have a shop build a 331 Cadillac for my 3w . It was an abandoned project that previous owner set up for sbc but I wanted to do something different . This will be my first Cadillac motor . I have read a little bit on here from searches regarding caddy motors .
I was hoping maybe some guys with experience running similar engine might have some suggestions as far as camshaft , heads, or other parts etc . I thought I read that if I use a 1955 331 , I could possibly use later heads from a larger motor for better performance. I was thinking that with more compression, later heads , the right camshaft and a multi carb intake setup that it should make decent power . Not trying to push it to the max stretching every bit of power out possible , car will see lots of daily driving duty .
I also had been looking at intakes and wasn’t sure if I’d be better of going 3x2 or 2x2 ? look forward to your replies /insight .

 

Those Lard Ass Cadillacs could really move back then.
That same engine in light 3 Window is pretty much a rocket.
Any "upgrade" is really just for sound or looks. The big deal is having that engine in a 3 Window.

 

https://www.jalopyjournal.com/forum/threads/tech-info-cadillac-ohv-v8s-1949-1962.8282/

 

Here's another good thread:
https://www.jalopyjournal.com/forum/threads/lets-talk-cadillac-331s-365-and-390s.1015067/

 

'55 is the first year for the "bare back" block which opens a lot of transmission possibilities, however, none cheap. Most important consideration is to build a well prepared and balanced block (rods, rebuilt vibration damper, line boring, turned crank). These engines were never intended to be "rev" monsters, you are pushing a mildly built up engine to 5000 rpm. I know. The 56-58 heads have larger exhaust ports, but try to avoid '56 as cracking has been reported. With the larger port heads you can use Sanderson headers ($$$). Which brings up weight. These motors are heavy, a factory cast iron dual quad manifold with Rochester 4GCs weighs 73 lbs! Find an aluminum aftermarket, any combination. Use alternator and reduction gear starter, along with above listed stuff, a savings of 50 lbs.

 

Am I understanding right that only the 1955 331 can bolt on the later year Cadillac heads ? The earlier year 331’s can’t ?

 

Build it to stock specs. It'll be plenty fast, super smooth, and easy on the hard parts.

You don't treat these like a SBC.

All the best - Tim

 

What rpm range do you suggest I stay below with one of these caddy motors ?

 

The most powerful of the 331's in the '55 Eldorado peaked at 4800 RPM. On average about 4500 is the max with the Caddy valvetrain. They're all about the torque.

 

Building a basically stock Cad eng, will give you great reliability and tons of torque and in a 3W you’ll shread tyres easily if that’s what you’re looking for.
Once dressed up with rocker covers,valley and alloy intake manifold and a good set of headers show me a better looking setup.
As said they are used to carting around a few tons+ of car in stock form and still get along well.

 

yeah, I’m sure it’ll be plenty in a stripped down 3w . I’ve got a little over 350hp in my other 32 which im guessing is probably similar weight wise and that car runs really well . With traditional bias ply you’re pretty limited traction wise anyways .
The 3w will just be a bit slower than the other . What would a rebuilt 331 make HP wise roughly ? 250 ?

 

210 is stated standard, better induction,a cam and headers would obviously help , more than enough for most in a lightweight car.
As said, dressed up a delight either way.

 

LOL!

"Smooth as a gravy sandwich."

That's a new one on me. Got to store that one away in my mental archives for future use.

 

the 331 in my '46 was 10:1. Ran an Isky cam (about 260-280 advertised duration) and 3 deuces on offy.

If I were building the same engine today I would shoot for 9:1 or 9.5:1. 220 to 230 duration @.050 and lift in the .460-.470 range. I like a roller timing chain instead of a link belt. if you are not going to run it hard set it up with in the middle of the specs range. Run good tri metal bearings and if you can find them for it plasma molly rings are really easy on the block, otherwise cast iron rings will probably be your best bet. A 2x4 is actually a better set up that 2 or 3 dueces.

OK so now you got my ideas what are yours?

 

Mine is a 390 10:1 cr balanced with BW-T10 Halibrand QC and this cam in 33-window.

 

Hmmm. . . . A gravy "sammidge" sounds like what they might serve you for dinner if you had to spend a rough night in jail.


All this reminds me of another word I found for the first time on the HAMB some years ago. It seems to have only fairly regional usage though. I'm going to have to work harder to spread the word in the midwest.

"Skookum"

https://www.jalopyjournal.com/forum/search/328377897/?q=skookum&o=relevance

A good gravy sammidge sounds skookum to me! As long as I don't have to go to jail to get one.

 

I keep mine under 5,000 most of the time.

I've done significant work to it with valvetrain, ignition, and clearances. Mine will easily spin to 6k. But I don't spin it like that anymore. While it will spin easily all the fun is from 0-3800 RPM. They pull like crazy and there is no reason to risk ruining a great thing.

Stock they are plenty. If you plan for off idle to 4k you'll have more fun than most.

 

PS - if you want an engine to spin up build a 327 Chevy. Also great engines. But they are two different ends of a spectrum.

The torque and smoothness of the Cad will win you over though.

 

and the sheer beauty of its looks

 

i think you’re opinion /ideas are very helpful since you’ve already built and driven your 331 combo for enough time to evaluate it and know the changes you’d make. I think a middle of the road build makes sense, probably get a little more reliability/durability over a build that is trying to squeeze every last drop of power out of it .
I think I will try and keep the rear end gears kinda tall in the quickchange to keep the RPMs down since the motor operates a bit lower than your typical sbc .
Plus it’ll make it a little easier to do highway and freeway .

 

Moriarity was kind enough to sell me his original 3x2 intake , gonna send it off for some polishing .

 

So I had a spare gm manual style tremec tko 600 transmission collecting dust from another project , but I’m unsure if it’ll work . The only place I found online that had an adapter kit says it’s for 49-53 Cadillac 331’s . The 331 I recently purchased is a 1955 331 .
Any caddy guys able to explain why or why not the pictured kit would work with a 1955 331 ?
I was only considering this option due to having a spare trans on hand and my motor has later heads and should make decent HP/TQ and I know that the trans could take ANY abuse thrown at it . If I can’t find any adapter kit I could use an early 3 speed , just not sure itd hold up without having to baby it all the time .

 

ok, I appreciate you clarifying the difference . Back to the drawing board .

 

They are a thing of beauty on their own!

 

http://www.wilcap.com/Cad-350 mt INST Web.pdf


Not sure if this old wilcap one would work , but I don’t see this same kit being offered anywhere currently

 

The same place offered this kit for 54 and later but it says for 365/390. So not sure if this would work. Thoughts ?