Internal snap rings replace wire clips. Some who have had problems with wire clip keepers coming out have installed Teflon buttons to keep the wrist pin in the piston. Many devices have been made to trap the wrist pin in the piston. Most are not effective, cause other damage, such as wear to the cylinder, and/or break. Internal snap rings always hold the wrist pin in the piston unless one or more of these problems exist:
1. Bent rod.
2. Case line bored out of parallel to the spigot holes, which is very common with the present rebuild type of line bore equipment.
3. Crank flexing or bending in the middle, pushing the rod sideways with every up and down motion. Traveling down, it pushes the pin forward in the hole, traveling up it pushes it the other way. This almost always happens with cast cranks, non-counterweighted cranks and even a high HP engine with a cheap forged crank. This problem was solved with the properly counterweighted and new forged Berg crankshafts over 18 years ago. No other company's crank meets this rigidity.
4. Endplay too loose allows crank to move back and forth too much. This moves rods back and forth, putting end thrust on the wrist pins. This also causes the brass distributor drive gear to wear prematurely.
Common sense should tell us that any one or a combination of the above engine problems can cause the keepers to burr up the piston or come out of the piston.
Note: If you are still not convinced and want better protection, we can machine the piston to accept double snap rings, LA PST021-4 cut pistons for double snap rings (requires 2 sets of new GB 203 keepers). This will allow us to reduce the wrist pin endplay.