How to ID the numbers on a Cadillac 472/500 to figure which it is.

[David P. Barter]

Folks,

I have supposedly been given a 197? 472/500 engine and want to see exactly what the motor is for c.i. What I don't know (as I am new to this) is where the numbers on the block are and how to cross reference them. This motor was out of the car it came in and the generous person that "donated" it to me does not know what it came out other than he was told it is a 472. When I compare to my in-car 472, there are obvious things that match and some things that don't. So I assume it is newer than my current 1969 motor but not sure if it is really a 472.

Can anyone point me in the right direction for this data?

[TJ Hopland]

Only way to know for sure is to look at casting number in the crank which requires the oil pan to be off or measure the stroke by sticking something down a spark plug hole and hand cranking the engine.

70-76 the block casting ended in 5200 for both the 472 and 500.   70-74 500's only came in Eldos so if its got the oil pan with the rear sump, notch in it, and 2 drain plugs it could be a 500.   The rest of the cars got the 472 and had the oil sump in the front (which would be backwards from a more typical engine like a Chevy.   75-76 all cars but the Seville got 500's.   The Eldorado pan is the closest to a typical GM setup and over the years the Cad motors have been popular to swap into other cars and trucks so its possible that was what someone had done or planned to do with this motor so it could be a 472,500,425, or 368 with an Eldorado pan. Its also possible that an original engine was replaced with what ever was available at the time.

500 has roughly a 4.3 stoke,  472 roughly 4.0  so you are looking for around a 1/4" difference. 

Block casting number is on the top leftish side of the flange where it butts to the transmission. 
About where the distributor would be on a Chevy.

1486238 was block casting number 68-69
1485200 was 70-76
1609110 was 77-79 425
1615255 was the 80-81 368 4bbl
1620734 was the 80-81 368 DEFI (including the 8-6-4)

1482464 was the 68-74 472 crank
1495094 was the 70 500 crank
1496793 was the 71-76 500 crank
1609142 was the 368 & 425 crank (same 4" stroke as the 472, smaller and tiny bores)

If nothing has been swapped around there are some visual clues to the year.  They changed small things like valve covers and the breathers over the years.  EGR started in 73.  HEI distributor on some 74 and for sure 75.  Electric choke started in 75.   Intake was single plane and aluminum on the 425's and 368's.  Timing cover slightly different on 425 / 368 vs the 472 / 500.   

[David P. Barter]

Great Info TJ Hopland. Lucky for me I have started the break down on the engine and the oil pan is off. It does have the front sump so that is a point in the direction of the 472. I will roll it over on the stand and see what I can find. Thanks again for all the info!

[Scot Minesinger]

99% sure that the firing order is different on the 500 than the 472.  The firing order is on the front of the intake manifold.  You can check this out by looking at shop manual for any Cadillac years 1970 thru 1976.  Further, the shop manual will also help make this distinction.

[David P. Barter]

Thanks Scott, I found that info and it matches my firing order on my running 472. Some evidence that it is a 472. Now just to figure out the year.

[TJ Hopland]

Picture of the intake carb pad, choke, and egr will narrow down the year.  If you have the heads off the type of pistons could narrow it down.  Head number can also narrow it down.    Head casting numbers are on on the top side center on the smog rail which is between the rocker arms.
 
1486250 was the 68-70 small chamber smog
1495950 was the 70 small chamber non smog
1497902 was the 71-73 small chamber smog
6024493 was the 74-76 large chamber smog
6024552 was the 74-76 large chamber non smog

The small chamber heads were for the high compression engines.  In 71 when GM mandated lower compression their fix was to put huge dishes in the pistons which was less than ideal for performance and emissions.  Guessing they were hoping they would be allowed to return to high compression but when that did not look like it was going to happen they re designed the heads to use a more typical piston.  Except for the 70 the difference in smog and non smog heads is just if the passage was drilled.     

Only difference between a 472 and 500 is the crank and pistons.  Everything else was the same including the firing order.  Depending on the year there could have been differences like the oil pan if it was in a Eldo or a RWD car.

What is different about the 472-500-425-368 family was the #1 cylinder is on the right side, not the left like many other GM's.    The firing order is also not the same as many of the other GM's of the era.   I think the firing order is the same as the current LS engines.  Supposedly some of the designers of this engine went on to Ford to do the 460 so the 460 has some similarities to the 472 family.