is this caddy a 500?

Hi guys am off to look at a 74 Eldo today VIN # is 6L47S4Q432156 Eng # 640432156. Is there anyway to check its a 500?

 

Yep, but it's a "low compression" 500......

 

Hi ken, have pretty ltd knowledge on the caddys, are some mills high compression whilst others are low? What would the compression ratio be?

 

Snag it anyway, its still a 500. High nickel block, and you can do a ton of stuff with it. Easier to find heads when you already got the engine.

Ken do you have any source for checking the #'s? The only way I've ever been able to validate the CI is to measure the stroke. But then again thats only cause they are almost always out of the car.

 

I beilieve the low compression 500s were 9:1, where as the high compression 500s were 10.2:1. Dont quote me on that but im fairly certian those are the numbers. Im also thinking that 73 or 74 was the first year for low compression. But again im not 100% on that...

 

10:1 High Compression '70 and some '71

Low Compression When emissions started kicking in
8.5:1 '72
8.25:1 by '74

Its all in the heads, so you can get some aftermarket heads, or hunt down an early set.

The only way I know to tell the 472 from the 500 is to measure the stroke. They are identicle in everyway. I can't tell you how many 500 engines I've checked out to find they are 472's

472 stroke 4.06
500 stroke 4.3


EDIT: Or you can deck the block to close down those heads and get a higher CR.

 

The 500's and 472's have the number 5200 cast onto the back of the block next to the oil sender.the smaller bore 425 motors have a different casting number.
The eldo's only had 472's in 68 and 69,500's from 70-75 and changed to a 425 in 76.

 

if it's the original motor it's a 500. But who knows if it's the original after all this time. So as said the only sure way is to measure the stroke.

 

What he said! Devilles had 472s and eldos had 500s unless its been messed with!

 

I could be wrong but I believe all Caddys from 72-77 had 500 and in 78 they downsized to a 425.
A set of early small chamber heads from 472 or 500 (72) back makes a ****load of compression on later motors in the 12:1 range as I understand it.

 

Hey Pete,

I have some Caddy ID info, I'll try to Email you the attachments,

Dan

 

I read somewhere that putting 425 heads on a 472/500 will bump the comp ratio and flow better???

I love cad motors but don't know squat about them.

 

Thanks Dan, got your email, really apprteciate it mate. Am off looking at her in the morning. Once again thanks.

 

75-76 all big caddys had 500.
In 77 they went to 425s.
RWD Sevilles had Olds 350s.

 

Rear wheel drive devilles from 69-75 came with 472's 76 was the one year they put a 500 in there then they went 425

 

70-76 Eldo was 500 Full size Cads only had the 500 in 75 & 76

 

Got it! Needs some work but Im stoked.