By: Dick Larrowe # 68

With Credit to Chuck Small (A.K.A Dr. 235)

53 Powerglide - 54-63 235 54-58 261
 (also applies to 216 & early 235, when installing a full pressure crank)

A. Factory return hole for bypass filter. Plug hole with a pipe plug, using Red Loctite on threads. 

B. New hole for line to remote filter (see figure 2). Drill the hole to 37/64", and tap for 3/8" pipe thread. Use a skip tooth tap to get clean threads. Install fitting and line to remote filter. Available from Trans-Dapt, Mr. Gasket, Amsoil, or use a recycled remote fitting from a GM off-road truck.
C. Factory hole and boss for bypass filter and oil pressure gauge using a "T" fitting. Drill this hole to 37/64" and tap for 3/8" pipe threads. This is where the line from the remote filter returns oil to the main oil galley.* See figure1.

D. New hole for oil pressure gauge. Drill hole 21/64" and tap for 1/8" pipe thread. See figure 1.

E. End holes for main oil galley. If core plugs are present, ream and tap for 3/8" pipe plugs and seal with Red Loctite. Don't go to deep or you will cut off oil from front and rear main bearings! Some blocks already have 3/8" pipe plugs from the factory. *See figure 1.
F. Factory hole where line from oil pump hooks to block. 

G. 1/8" pipe plug down in hole "F" - see figures 3 and 2. Inside hole "F", down 1-3/8" the hole gets smaller, this is where you tap it for the 1/8" pipe plug. This blocks oil from going to the main oil galley. Use Red Loctite on threads. See "G" on *figure 2.

Main bearings. Fully grooved main bearings are not needed for street use, but give 360 degree oiling to the rods.

Oil pressure. Pressure will be about 60 pounds when cold and at highway speed. About 30 pounds at idle.

Oil lines. Lines should be no smaller then 3/8" ID. The factory fitting at the oil pump and "F" are smaller so 3/8" would be fine. Lines should be high temperature and able to withstand 100 pounds of pressure.

Oil filter. Mount filter lower than the block so oil does not drain out when the engine is shut off.

* Alternative: Plug hole C and run the oil filter return line to a fitting at the front oil galley (E). This will save a drilling and tapping step, but may not be practical due to location of alternator or other components.