Cadillac engine knowledge

1968-'69 472: 1486238

 

1970-'76 472 & 500: 1485200 (1486200 was used on some 1974-'76 500 engines)

 

1977-'79 425: 1609110

 

1980-'85 368: 1615255 Carb; 1620734 EFI

1968-'74 472: 1486424

 

1970 500: 1495094

 

1971-'76 500: 1496793

 

1977-'79 425: 1609142R

 

1980-'85 368: 1609142

(Stroke can be measured through spark plug hole if the engine will turn over.)

 

1968-'74 472, 1977-'79 425, 1980-'85 368: 4.060" (less than 4-1/8")

 

1970-'76 500: 4.300" (more than 4-1/4")

(Usually in the center of the head under the valve cover.)

 

1968-'69 472: 1486250

 

1970 472 & 500: 1495950, 1497902, 1486250

 

1971-'73 472 & 500: 1497902

 

1974-'76 472 & 500: 6024493, 6024552

 

472 and 500 heads have the last 3 digits of the casting number in a recess under a center intake port, visible from the lifter valley with a mirror.  

 

1977-'79 425: 1609112, 1609423 (last 3 usually on driver's front / pass. rear exhaust port)

 

1980-'85 368: 1615188, others unknown. The 4-6-8 head is substantially different than the regular head, and the rocker assemblies are not directly interchangeable.

The biggest gains in power output come with cylinder head work. Pre-1974 heads are small chamber 76 cc's and are good for around 12-13 to 1 compression when a flat top piston is fitted. Race gas, alcohol or propane fuel must be used. The 1974 and later open chamber heads have 120 cc chambers giving compression ratios of 7.5-9 to 1 depending on the piston used. The 1977-'79 425 heads have 108cc chambers giving about 10:1 compression ratio depending on the piston used. The 425 heads have restricted air flow due to their port design making them the least desirable for modification. The head gasket is different as well.  Big gains can be made by adding larger valves. The valve sizes can be boosted to 2.19"/1.84" without worry of hitting the water jackets. The usual porting, valve unshrouding and minor bowl modifications will work, although the short-side radius should be left alone to avoid drastic differences in airflow. Roughly 20 hp can be gained by this work alone and most of that comes from the larger valves.

Blocks should get the standard deburring. A drain hole can be drilled into the rear of the lifter valley for better oil drain back and a spillway can be added to the oval hole at the front of the block to better lubricate the timing chain and the camshaft thrust face. Incidentally, a later block has 1/2 inch oil galleries for increased flow through the block, so it makes a good performance base. If the front cover has [[rust]] pitting from the water pump, it can be saved by [[sandblasting]] and filling the [[Pitted rust|pits]] with JB Weld and then painting. One more thing about blocks, a 472 can be made into a 500 by swapping in the 500 crank and pistons, although on 1968-'69 engines, a slight amount of notching is necessary at the bottom of the cylinder bores.

Crank end-play, minimum- 0.008"

Rod side clearance- 0.035"

Top ring gap- 0.020"

Second ring gap- 0.018"

The basic 472 and the later 500 engines both use a Buick/Pontiac/Olds/Cadillac (BOPC) bell housing bolt pattern, so a TH400 automatic will bolt right up to the back of the block as long as the proper Cadillac flexplate and torque converter are used. The TH425 front-drive automatic transaxle also fits these engines as used in the Eldorado, although a special dual-sump oil pan and pickup are used with these transmissions due to the required half shaft clearance. Any RWD engine can be converted to FWD and vice versa if the proper oil pan and pickup are used, although two of the main cap bolts must be removed and swapped for studs with standoffs to mount the pickup bracket. Another good thing about these engines using a TH400 transmission is that a BOPC patterned case can be assembled with the Chevy 4x4 tailshaft and associated hardware for use in an off-road truck. The engine weight is approximately 600 pounds fully dressed and splits the difference between small and big block Chevy, so suspension modifications are not usually necessary. Transfer case choice for a 4x4 should be a NP205, as fitted to some mid/late 1970's Chevy 1 ton trucks. The NP205 is a strong gear-driven transfer case and holds up nicely to the big Caddy's torque output.

The [http://www.transmissioncenter.org/compushift_4l60e_4l80e.htm Compushift ECM (Electronic Control Module)] for the GM 4L60E/4L80E costs about $1150.00. A less expensive controller is the [http://www.optishift.com/ OptiShift]; cost for it is around $600.00. For about half that amount, the [http://www.msgpio.com/manuals/mshift/4L60e.html MegaShift™ Transmission Controller] is available. It requires assembly and some knowledge of electrical circuitry, etc.