Hot Rods Let's talk Cadillac 331's, 365 and 390's

https://www.lakeheaders.com/
He says he is supposed to be getting 5 Caddy 4-71 blower intakes cast in June
I'm thinking a blower would warm up a 331 real nice

 

This ‘61 390 was very low miles out of a Hearst having 26k miles on it. The block was hot tanked, magnafluxed, deburred, main caps shot peened, using ARP Main Bolts, align honed, decked to piston height .004”. Cam journals were align honed and new bearings installed. Block was fitted with brass freeze plugs/oil plugs. Crank was welded to 4” stroke, ground .010” (rod & mains), shot penned, heat treated & stress relived. Stock rods were mangnafluxed, bushed, drilled and honed for Sbc 0.927” wrist pins, indexed/straightened and shot peened, using ARP rod bolts. Even though there was no taper the bores and really didn’t need to be bored we went for it anyway having my friends at Diamond Racing make a custom set of Forged .060“ machined for 3 rings using Total Seal Rings gapped Top .019”, 2nd .018”, Oil STD, pistons machined for full floating SBC 0.927” light weight custom pins. Pistons machined for valve reliefs, tops indexed and machined for 9.6:1 CR. Internals complete balance with steel flywheel and reconditioned balancer using ARP Bolts.
Heads were magnafluxed, milled .030”, new SS valves Intake 2.05”, Exhaust 1.60”, cc/88, bowles relived and blended, ported and polished, hardened seats and bronze bushings installed, Fel-Pro head gaskets, Comp valve springs, retainers and keepers, 1.7 Harland Sharpe roller rockers with chromed shafts, ARP Head Bolts. Cam custom ground solid roller, split duration 277/281. (@.50 234/238) lift .495”/.515”, Centerline 106/114, Lobe Separation 110. Smith Bro’s custom length hardened push rods. This sort of wraps up what was done on the build of this 414ci caddy.

Regarding the concerns of low oil pressure. First, gauges checked and reading correctly. I talked to an old caddy race engine builder in AZ today, saying with the clearances it was built with everything is about normal however, he did suggest using a BBC oil pump modified to replace the caddy pump for improved volume and pressure so I will be looking into it.

 

It is not the gauges, had checked with two SW gauges. Since posting I have talked to a couple reputable race engine builders and one very familiar with caddy’s so saying with the clearances it was built with the pressure readings are about right however, it was suggested for improved volume and pressure to use a modified BBC pump to replace the caddy pump so will be looking into it.

 

Thanks for the info. I would be interested in the BBC oil pump swap.

 

Your not alone in this thought roothawg

 

That makes three of us...

 

Four.

 

Hey guys... Check out my ‘61 Cadillac 390 build that just went live on the Hot Rod Magazine website.


https://www.hotrod.com/articles/cadillac-390-engine-build/

 

That looks like the right Diameter Scott but man that looks really tall!

 

I was really glad to see that published. I did have one question. I read that you guys used a replacement dampener. Where did you find that? Oh and those guys at JE never got back with me. I gave up. Thanks for trying though.

 

I haven’t messed with it yet. I will have to check and see once I get everything out. It’s all crammed into the corner of my little garage at the moment.


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Shoot... I’m so sorry JE never called you back, I passed along your contact info. It wasn’t actually a replacement damper, just a cleaned up original.

 

Speedway Motors has the Offy 3x2 high rise intake manifold for these engines on sale now for $513.99, reg $703. I've been on the fence about what type of manifold I want to run on my 331. Just placed my order.

 

You tried brother. That’s all we can do. Ok, I was wondering if they made them aftermarket. I have one, just needs to be cleaned up and inspected.

 

Check your PM's

 

Hey guys, as soon as I get more info about using a BBC pump I will pass it on. I was just recently informed about it from a fella who’s friend has the scoop on it so, hopefully he will get me in touch with this gentleman.

 

Here are the Diamond Racing Forged pistons I had made for my 390.

 

You could sell at least 5.

 

What was the final compression ratio? Wonder if they could use their previous specs and build more sets? Also, why offset grind the crank, make new pistons and use the stock rods? This puzzles me. If you had to make new pistons, why not take advantage of the increased stroke? In essence, did you just move the pin height up?

 

Has 9.6 cr, pin height was moved up. Had these pistons made for running a blower setup.

 

OK, gotcha.

 

Yup!


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Got the 390 in my '40 too-many door running yesterday, just long enough to break the cam in. Now to re-torque the heads and change the oil & filter. Still a long way to go on this one...

 

Can you tell us who ground the roller cam?.... I've spoken with a few places about doing a custom grind roller cam but so far no luck.
Thanks,
Jim.


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No idea who ground the cam. Got it with no box just timing tag.

 

This is a general question about these early Cad motors, but I was chatting to someone the other day about the merits/difficulties of fitting a big block Chevy oil pump to the Cad motor as an upgrade. We both read about this in an old article on the Allard website. I'm yet to get this far with my motor but he said that the pumps bear no real similarity and as such would prove hard to make work. This leads me to my main question however. In the same article it states that although the Cad will rev, you don't want to take it too high as they start to become fragile. I know there's a question around why you'd need to rev a motor that high when it makes good low down torque, but I was curious as to whether anyone had experience of anything breaking on these engines? They seem well engineered to me, but I'm keen to try and sort problem areas as I build my motor.
Thanks,
Jim


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I think the hard part will be to get the ports to flow enough. Cast pistons are the next on the list along with the stock rods. I put BBC rods and forged SBC pistons in mine but it has yet to run.

 

They are almost a carbon copy of the SBC with a couple of exceptions. The raised intake and the siamese exhaust ports, but basically it's a stroker sbc. I doubt they are "fragile". I don't know how much you can expect at higher rpms though.

Cody Parr campaigned one with a 6-71 in a car called "The Apache". It was an altered in the 50's-60's. I owned this car in the 80's, but haven't seen it in years.

 

390 heads are far better than the 331 heads. Even the 390 heads don't flow well. After extensive porting my 390 heads flow about what a decent STOCK SBC head flows.