Tech Info: Cadillac OHV V8's 1949-1962

I would agree.

 

My engine guys says on a low performance iron block, he wouldn't go below .140 on the thrust face. High compression (9:1 or more) he'd prefer to see .180. Anything with a power-adder .250.

 

Hi All, i'm nailing down the spec of my 1950 331 rebuild. Punched to 4.030" using 390 heads with 1.6" Ex & 2.02In, an SLR Cam, Scat 7.1" H Beam rods and Ross Forged pistons, Sanderson CAD390 Headers and a Weiand WCFB Base 2x4 Intake with two AFB Carters. Some compromises along the way but aiming for 350HP + at 5000rpm. doing my own porting and will set the compression at 10.5:1.

Does anyone have advice regarding a modern harmonic balancer that will fit onto the nose of my 331 crank? I believe these cranks to be internally balanced.

 

I have a '50 331 and a LaSalle trans. Is there a source for fly wheels?

 

Try Wilcap for that.

 

Cool oddball trans setup I scored at Hershey this past week for my caddy build. Stude 3 spd with a McBar Machine Shop adapter kit and a floor shift. Need to find the March '54 Hot Rod article with details on the installation to keep for the files. Nice thing is the super short tail-shaft compared to the Lasalle.

 

Yes, they are internally balanced. You will likely need some tungsten weights for the crank to get the rotating assembly to balance with the lighter pistons.

I didn't look too hard for an aftermarket harmonic balancer, but it is probably a good idea.

 

Stock (very heavy) Caddy or Olds flywheel should work. They were used in the commercial chassis. I found an aluminum aftermarket flywheel somewhere. There seem to be some around. Saw one for sale a few weeks back but didn't pay much attention so I've forgotten where.

 

Ask and ye shall receive @IronTrap .

 

Good stuff guys. Glad to see the Caddy thread alive.

 

Dang Thanks SO MUCH @Speed Gems ! Gonna Print those out now. DO you have the other pages of the install? Looks like it is continued on page 50? Cool to have with the other paperwork/notes I have written down for the car. Appreciate it.

Here's a shotof the engine and the Stude Trans hanging in the car. I need to tweak a few things for the floor shifter or tweak for a Jeep shifter top but it should fit in there nicely!

 

Significant progress to report with my 1950 331CuIn Cadillac engine rebuild. After 6 wks or so of researching, designing, sourcing parts and scratching heads I've taken the plunge & yesterday bought the parts for my rebuild. Thanks to many of you on here for freely sharing your knowledge & hard won experience that has enabled me to press on confidently with my stab at this engine.
It was a 160HP @ 3800rpm engine, i'm anticipating it'll be a 370CuIn 350HP+ @ 5000rpm engine going back in. Here is the spec I've settled on- a few compromises but hey ho. I'm sure i'll break the down stream drive train so thinking about sourcing a 59-62 Scrap Caddy, importing it in a container & stripping the parts off it.

- 1959 Caddy 390Heads (had them magnflux & pressure checked)
- original crank but re-balanced with new parts
- SCAT 2-454-7100-2200 H Beam stainless rods 7.1" ctrs (up from 6 5/8") with a small end bush to reduce it from 0.990" (BBC) to 0.927" (SBC Wrist pins in the Ross Pistons)
- Ross 90455 forged aluminium pistons + block bored to 4.030" (up from 3 13/16")
- CR set at 10.5:1 up from 7.5:1
- Steve Long Cam Int 0.478" lift 214deg @ 050 Exh 0.486" 218deg @ 050 110 deg LCA (wanted 108deg LCA but we're regrinding old cams rather than starting with a blank)
- Manley custom stainless valves, 1.6" Exh (up from 1.5" in 390 or 1.44 in 331), 2.02" Int (up from 1.875" in 390 or 1.75" in 331). 30deg seat on int with 20deg back cut + conformation groove on face. 45deg seat on Exh with 30 deg back cut and 0.025" rad on face. Bead type valve locks + wear caps.
- PAC 1220 Beehive, flat wire Valve springs & 10deg retainers. having to cut wider spring seats on the heads to accomodate.
- Porting & head work by yours truly- port CSA sufficient as is for good gas flow speed, just cleaning & flaring into new hard valve seats with some port bias where i can to promote barrel swirl.
- Sanderson Headers CAD 391 with black ceramic. Bit of a compromise as the primaries are shorter than ideal but key in twisted crank lower revving V8 is to have good long length secondaries, perhaps 48" or more.
- Weind WCFB Intake with 1957 reconditioned 2x4 Carter AFB's. a compromise again as i could find the Weind AFB intake (flows lots better). May move to Offy 3X2 intake & Stromberg 97's Carb set up if Offy ever do start selling that intake again
- new Caddy 390 rockers (wanted Aluminium but none available so trying to work out if i can modify a FordFE 390 set which looks similar)
- Trend custom length hollow pushrods
- Chevy Hyd tappets

It should go back in looking like an engine that was rodded in the 50's, with some patina to it (i'm purposefully not painting the rusty Caddy rocker covers). And, with that cam & exhaust, it should sound burbly & cool. Can't wait to get the machining done and on with the building.

 

@RaygunUK, sounds like your project deserves its own build thread! Get it started and we'll all be watching!

 

I'm a bit embarrassed to as mostly i'm following the paths forged by HAMB Members such as C322348, Dyce, Roothawg, Marcus etc. And with a healthy dose of David Vizard reading thrown in (ANYONE building fast engines should read David Vizard & A Graham Bell books). I'll start a thread, will be at great pains to credit those above & certainly will share how it turns out.

 

Here's the rest of that article @IronTrap sorry to leave you hanging like that.

 

Don't be embarrassed, we're all here to have fun. Make some mistakes, fix 'em, and add to the body of Caddy knowledge!

 

Thanks so much @Speed Gems ! The HAMB comes through again!

 

C322348 and RayGunUK,
Wanted to ask you a question: why use the BBC rods and special (standard Chevy) pistons? I read where the stock 390 rods and pistons would work in a 331 swap. I suppose a guy could get a set of forged 390 spec pistons from Ross or Jahns, etc...? Just wondering...

 

I wanted to see what kind of performance could be had out of the old Caddy. Stock cast pistons would have worked just fine but not with the long rods. I just wanted to try that. Looking back, getting custom pistons would have saved time and expense with the offset crank grinding.

Sometimes when you get into these projects you learn s few lessons along the way. I thought the SBC pistons would save time and money in the long run but they really didn’t.


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It seems like the 390 crank would have to have the mains ground down to fit 331 saddles, but wouldn’t all the rotating assembly fit into a 4” bored 331 block (with proper rod clearing on pan rail if needed)?


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New Skool 331 Caddy Build
You can see my build here:

https://www.jalopyjournal.com/forum/index.php?threads/New-Skool-331-Caddy-Build.803459/

I think all of that is explained.


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Thanks... my head is spinning from all the info I’ve read lately... I’ll reread your thread


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It has been nearly 5 years since I started, so I don’t remember stuff either!


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There is a discussion about Rod length here. http://www.enginebuildermag.com/2016/08/understanding-rod-ratios/
I was attracted to the idea of a longer rod giving more torque, lower side thrusts (less friction) & using a lighter forged Aluminium piston in these fairly low revving engines. Time will tell. It’s a lot of expense to go to though, the rods & the machining on them has been costly.


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The 331-390 series had a tall deck so there is much room to play. That’s how I ended up with a 7.1 rod length. The later 390-429 series had a shorter deck height. Might still be opportunity there though.


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C323348,

Did you machinist have to trim the diameter of 390 crank throws down to fit 390 crank into the 331 block?


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I “think” the main journal diameter is the same but the bearing width is different. The only real interference that cropped up (once the bearing width had been addressed) was the rod bolt to the cam lobes. About 1/16” was trimmed off the corner of the rod bolt heads. The trim didn’t weaken the bolt at all.

 

Thanks for the reply.. have you made plans to fire it up yet?


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Not yet. I need to fabricate a pilot bushing because I can’t find one. Of course nobody has one I can measure so I have to figure it out forensically.

Once I get the engine installed I will need to plumb everything.

Always seems to take months to do a few days work...


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Anyone have a line on where to get bearings?
Need some .010 under main bearings for a 331.


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