500 Block Question

[leggett]

I got a block off ebay with the following specs. Sorry for my stupidity but can someone tell me what they mean when it comes to rebuilding it for my 73 eldorado.

Bore size: 4.300
main : 3.425
cast 495280

I was going to purchase a rebuild kit but do not know what I need. Plus I was going to use my stock heads off my 73 that I just rebuilt.

Thank you
Jason

[lux hauler]

This should help to identify some Cadillac engines........
http://www.geocities.com/MotorCity/Pit/9364/guide/Engineid.html
Cadillac 500 / 472 Engine Identification.
All the Cadillac Big Blocks are strong engines capable of producing huge amounts of street useable low RPM power. Of the four the 500 is by far the more popular with the 472 coming in a close second. To distinguish between these two can be difficult for someone new to Cadillac engines. You can't just ask the guy at the salvage yard if the engine is a 472, or 500. Chances are he will not know. Or worse yet he may be calling them all 500's! If you do end up with a 472 all is not lost, the blocks on the two engines are the same. So any 472 can be converted to a 500. Its as simple as swapping in the crank and pistons from a 500. "If its an older 6238 series 472 block, one made in 1968 or 1969 it will require notches at the bottom of the cylinder for better rod nuts clearance. " Since the conversion adds up to extra parts and machine work it would be better to get a 500 the first time around.

The 500 from the 472 & 425

To make thing more confusing the newer 472 and 500 cid Cadillac engines both have the same block number. It ends with 5200. 472s made in 1968 and 1969 have the number 6238. This number can be found cast into the engine block near the top of the bellhouseing flange adjacent to the oil pressure-sending unit. Other than that I don't think you will be able to tell what year the engine is from these numbers. You'll have to look at the pistons and head casting numbers in order to do that. The 5200 blocks have improved oil passages and will take either a 472 or a 500 crank with out modifications to the cylinders

One way to be sure of the engine displacement is to measure the stroke. The 500s have a 4.300" stroke and the 472 have a 4.060" stroke. The 425 and the 472 have the same stroke so this method will only distinguish the two from the 500. First remove one of the spark plugs and turn the crank until the engine is at top dead center. Use a piece of stiff wire or something similar for the measurement. What you want to do is take a measurement at top bead center then a second measurement at bottom dead center. The 425 and 472 will have a 4 1/16-inch stroke. The 500s are closer to 5 5/16 or 4.304 inches. This makes the 472’s compression height about .110 higher than the 500. The 500's stroke is about 1/4 inches longer than the 472.

The 425s have a single plane intake manifold with all the runners dipping down towards the carb. The 425 also has a rear oil sump that doesn't go all the way back like an Eldorado. If the engine is out of the car remove the flex plate and inspect the end of the crank. The 425 has a crank flange that is different from the 472 and 500 cid engines.

Another way would be to pull the oil pan and check the crankshaft. 500s have a small casting number " 094 or a 793" between the # 4 main and the rear rod journal, while the 472 casting number is on the edge of the third counterweight. The Different Cranks can be identified by the last three numbers in there serial number.

A. 425
All 425 crank numbers end in 142. The 425's number is found on the first journal near the nose

B. 472
The 472 ends with 424 Its number is found on the edge of the third counter weight

C. 500
The 500 ends in either 094 or 793. The 500's number is found just behind the fourth journal.

The full sized rear wheel drive Cadillacs made from 1968 to 1974 all had 472 cid engines. The 1970 to 1976 Eldorados had 500s. 1975 and 1976 rear wheel drive full sized cads had 500s as well.

From 1968 to 1973 all Cadillac engines had points distributors. Half the 1974 models had points many had the newer HEI. All the 1975 and 1976 cad engines had HEI.


VIN number

Another helpful tool for engine identification is the donor car VIN number. Chiltons mini Manuel #7462 give details on reading the VIN numbers. Don't trust the VIN number 100 percent I have seen to many engine swaps to have 100% trust in the VIN number engine id.

In a 1970 to 1976 Cadillac the fifth digit in the VIN code will either be an S (500 C. I.) Or it will be an R (472 C.I). The 6th digit in the VIN number indicates the year.

Q = made in Detroit
E = made in Linden, NJ.

[MilesO]

You may want to call MTS and order their very informative Cadillac Tech book and other info they offer.
This will give you a lot of basic info and answer a lot of questions relating to interchangeability of parts, etc.
Money & time well spent.

[STDog]

I got a block off ebay with the following specs. Sorry for my stupidity but can someone tell me what they mean when it comes to rebuilding it for my 73 eldorado.

Bore size: 4.300
main : 3.425
cast 495280

I was going to purchase a rebuild kit but do not know what I need. Plus I was going to use my stock heads off my 73 that I just rebuilt.


You'll need the correct pistons and rods for you heads. The block doesn't change much after the 500 came out.

The bore listed is stock, but you should have it checked. Not that cadillac had several piston sizes. Look for letters near the cylinders. The tell you the correct piston size. Since you cannot easily get the between sizes now, you probably have to get them all bores to match a standard size.

[dave_brode]

Jason,

Could be a 68/69 block. Look to see if the bottom of the bores are nothed. If not, and it's a 4.300" bore, I'd say that's what it is.
Dave



leggett"]I got a block off ebay with the following specs. Sorry for my stupidity but can someone tell me what they mean when it comes to rebuilding it for my 73 eldorado.

Bore size: 4.300
main : 3.425
cast 495280

I was going to purchase a rebuild kit but do not know what I need. Plus I was going to use my stock heads off my 73 that I just rebuilt.

Thank you
Jason[/quote]

[leggett]

it does have the notches at bottom of bore.

[dave_brode]

leggett,

hmm. The #5280 was throwing me off. I thought that '70 up 472/500 blocks had #5200. Luxhauler said so too.

??? Did you get the crank? 4.304" stroke?
Dave


"]it does have the notches at bottom of bore.[/quote]

[lux hauler]

If you scratch around on that "5280" you might find it's actually 5200.

[leggett]

after getting my glasses it is 5200.

[dave_brode]

leggett,

Ahh. '70 up 472/500 block then. Since you want to use your 76cc heads, you'll need pistons to match. Afaik, oem 69-70 are only option for 9.5 to 10-1, other than new 472 pistons from KB. For a 500, '70 only pistons or KBs, Ebay Ross forgings for 10-1 or so. Stock '71-73 pistons [to match which ever crank you're using would work for 8-1 or so.
Dave




"]after getting my glasses it is 5200.[/quote]