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 472ís compression height about .110 higher than the 500. The 500's stroke is about 1/4 inches longer than the 472.

The 425 from the 472
Crank Flange 500 and 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.
Crank Flange 425
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 Cadillac 500 and 472 engines were made from 1968 till 1976 piston design is one way to tell tell which year your 472 or 500 was made
1974 to 1976 500 piston
 From 1974 to 1976 the cadillac 500 cid engine had a  8.5:1 compression piston.

1974 472 flat top piston
In 1974 the 472 had the 120-cc heads that ended in 493. This is the only year the 472 had a true flat top piston!

1971, 72, 73. 500 / 472 piston
1971 model 472ís had 8.5:1 compression. The pistons have a 47cc pocket that looks a little like a bathtub.

1970 10:1 Piston
The 1970 500 was the no smog motor it had the 76cc 950 heads with no smog rails. It also had the unique swirl chamber dome 10:1 pistons that look like a binocular.  The 950 heads weigh about 3 pounds less than other cad heads but should not be considered high performance because they don't flow any better than the others.

1968, 69, 70 472 Piston
From 1968 to 1970 the 472 had factory 10.5 to 1 pistons. These pistons have a swirl chamber dome that some say looks like a squashed peanut.  With the exception of some 1970 models ending in 950 the heads from these engines will end in 250 or 902 


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.

  General Engine Specifications Chart
Year Engine Vin Code Engine Letter Code Cubic Inch Rated Horsepower Rated Torque Bore & Stroke Compression Ratio Oil Pressure 
PSI
1968 - 1969 None None 472 375 @ 4400 525 @ 3000 4.300 X 4.060 10.5:1 33
1970 None None 472 375 @ 4400 525 @ 3000 4.300 X 4.060 10.0:1 35-40
1970 None None 500  400 @ 4400 550 @ 300 4.300" x 4.304" 10.0:1 35-40
1971 R 61E,Q 472 345 @ 4400 500 @ 2800 4.300 X 4.060 8.5:1 35-40
1971  S 61E,Q 500 365 @ 4400 535 @ 2800 4.300" x 4.304" 8.5:1 35-40
1972 R 62E,Q 472 220 @ 4000 365 @ 2400 4.300 X 4.060 8.5:1 35
1972 S 62E,Q 500 235 @ 3800 385 @ 2400 4.300" x 4.304" 8.5:1 35
1973 R 63E,Q 472 220 @ 4000 365 @ 2400 4.300 X 4.060 8.5:1 35
1973 S 63E,Q 500 235 @ 3800 385 @ 2400 4.300" x 4.304" 8.5:1 35
1974  R 64E,Q 472 205 @ 4000  365 @ 2400 4.300 X 4.060 8.5:1 35
1974  R 64E,Q  500 210 @ 3600 380 @ 2000 4.300" x 4.304" 8.5:1 35
1975 S 65E,Q 500 210 @ 3600 380 @ 2000 4.300" x 4.304" 8.5:1 35
1976 S 66E,Q 500 190 @ 3600 360 @ 2000 4.300" x 4.304" 8.5:1 35
  

One should note the Horsepower rating System was changed from gross to net in 1972. This is the reason for the charts lower power Ratings. The Only real loss of power came from the lowering of compression in 1970. Even that wasn't much the 500s compression for example was lowered from 10.0:1 to 8.5:1 The result was a loss about 35 hp and 15 ft pounds of torque.

I realize that even after reading all the available information on the subject it can still be confusing. A 100 % sure fire way to end up with a good 500 cid engine block would be to order one already machined from a high performance Cad Engine Company.

 Back to the Caddy Engine Guide

I hope you have found this engine Identification page helpful. If you have some helpful tips that I have over looked " and or corrections" please email them to me. This is an on going effort I'm constantly looking to improve it.  



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