To facilitate the flow of oil the size of the oil passage holes in the piston in the lower ring groove has been changed from .100 to .125″. (See Fig. 1172.) The width of the milled slot in the oil control ring was also increased.


To eliminate any possibility of pistons be- ing incorrectly assembled in an engine, the word “front” has been placed beside the arrow, that is, stamped on top of the piston. When the piston is correctly assembled in the engine, the arrow will point toward the front of the car (see Fig. 1121) and the split …



The following oversize piston rings have been released for service. These are in addition to the .010, .020 and .030″ oversize piston rings that have been available for some time. A-6150-BR piston ring .005″ oversize, 1⁄8” wide. A-6152-BR piston oil control ring .005″ oversize, 1⁄8”wide. A-6153-BR piston oil control ring .005″ oversize, 5/32” wide.


To assure maximum lubrication of the piston pins, a 5/32“ oil hole is now drilled through both piston pin bosses. (See Fig. 901.) In addition, the diameter of the pis- tons has been increased .001″. In production, new pistons are now fitted to cylinders with a clearance of from .0005 to .0025. In service, if …

Pistons Read More »

Piston Pin Retainer

The width of the A-6140 piston pin retainer has been changed from .120 over .123 to .115 over .116 and the retainer groove in the upper end of the rod narrowed down from .128 over .130 to .117 over .118. These changes provide a closer fit for the ring and add to the quietness of …

Piston Pin Retainer Read More »

Solid Skirt Pistons

A percentage of Model “A” cars are now being equipped with solid skirt pistons. These pistons are a trifle lighter than the slotted skirt design and consequently should not be used interchangeably. The piston heads in the solid skirt pistons are fitted with a non-expanding steel insert anchored to the center of the piston head. …

Solid Skirt Pistons Read More »

Installing Piston Pins

((618)) Under no circumstances should a hammer be used on the piston pin pilot and driver when installing a piston pin. Immersing the piston in boiling water for a minute or two will expand the piston pin hole sufficiently to permit easy installation. To correctly install pin first insert the piston pin pilot and driver …

Installing Piston Pins Read More »

Engine Connecting Rods

When connecting rods and bearing caps are assembled in new engines both the cap and the rod are marked with a number which corresponds with the number of the cylinder into which they are fitted. After taking up a connecting rod bearing be sure to replace the cap in its original position; that is, so …

Engine Connecting Rods Read More »

Installing New Engine Piston

When fitting a wrist pin in piston, select a pin which cannot be pressed into the piston by hand at room temperature. Next submerge the piston in boiling water allowing the piston to remain in the water from one to two minutes, then withdraw piston, wipe out piston pin holes with a clean cloth and …

Installing New Engine Piston Read More »

Fitting Pistons and Rings

“Model “A” pistons are fitted in cylinders loose on .002” and tight on .004” When fitting pistons, use a long feeler (thickness gauge) that extends the full length of the piston. Insert the feeler between the piston and cylinder wall on the opposite side of the piston from the slot in the skirt. When properly …

Fitting Pistons and Rings Read More »

Scroll to Top
Scroll to Top