500 Cadillac swap

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500/600

Royal Smart Person
Nov 17, 2018
1,167
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West Virginia
This is actually my second 500. The first was a 10:1 motor and it pinged and knocked so much I parked it for a long time. One day my contact at my favorite junkyard called to tell me there was a fresh 500 Sedan de Ville. Turns out it was a '75 and had factory EFI. I still have the intake. My machinist, who had done hundreds of air boat motors for the Seminoles and always used Cadillacs, was shocked to see it. He'd never seen one before. I built a low compression motor and was much happier.
Anyway the high compression engine I used the MTS high pressure pump and always had 50+ psi. Its important to use a very thin oil pump gasket to maintain that tight clearance.
Yes the blocks are supposed to be very hard. I've seen testimonials from fans that they tore down well cared for 472s and 500s with high miles and they still had crosshatch on the bores. Many guys rering them, slide in a cam and springs and race or tow with them.
The machine shop owner said Cadillacs seem to have very good rod bolts as he had seen broken rods but the big end was still intact on the crank journal.
The rods seem to be good enough for the rpm limit of the heads. Aluminum heads, big roller, that would be different. You can substitute Olds aftermarket rods.
They are the same length and rod journal size. There are weird parts combinations. 472 engine, 425 Olds rods, Olds 403 pistons. I was told about using Ford 429 pistons and Chevy 454 too.

Sounds like you already know what you need to know. If you in fact have small chamber heads on your current motor with bathtub dish pistons then you still have 10:1 compression. If you are intent on running such a small cam with 10:1 compression in such a large motor you will likely always fight pre-ignition. Of course you need to fix your oil problem first
 
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Oct 14, 2008
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Melville,Saskatchewan
Is the EFI intake really flat like the Olds 350 version? I wonder if it uses the same small throttle body?
 
Oct 14, 2008
8,806
7,746
113
Melville,Saskatchewan
I agree from the pics I have seen, the factory Cad intakes are all low profile. The Olds version is a low profile single plane intake, even compared to the carb intake.
 
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