piston replacement

iddie makel

New member
Well,I finally took one head off and found a piston with a hole in it.does anyone know if a piston can be replaced in a '55 Special without pulling the engine?If the engine has to come out ,can it be pulled without the transmission?As always,thanks to those of you who respond.
I've done this before, but the results weren't great. I didn't inspect the crankshaft enough and spun a bearing later. And then the next piston over broke away from it's connecting rod!! Why is there a hole in the piston? Did a valve break? If so your connecting rod bearing is probably shot. The force of the valve hitting the piston probably flattened the soft bearing material. That said, you can pull the piston with the engine in the car.

1.Pull the oil pan. You may have to raise the motor slightly for the pan to clear the crossmember. A jack on the tranny will work for this after unbolting the motor mounts.

2. Remove the bearing cap for the offending piston. This is a good time to check the bearing. The crankshaft surface should look like a mirror! If it has any roughness you should probably pull the crank and have a machine shop check it out. If a micrometer is available check the connecting rod journal for roundness. Measure it in several places.

3. Rent a Ridge Reamer from Autozone and remove the ridge from the top of the cylinder.

4. Tap the piston with a piece of wood (tool or broom handle?) out through the top of the engine (from under the engine up through the cylinder). Be careful that The connecting rod doesn't scratch the cylinder as it goes through.

5. Replace the piston on the connecting rod. Check the rod for any bend or twist. Get new rings for the new piston and a new connecting rod bearing (check the old bearing to see if it's already oversized)!

6. Using a ring compressor, oil and install the new piston and rod down through the cylinder, again being careful not to score the cylinder. Also be careful not to damage the connecting rod journal with the connecting rod bolts. Make sure the piston is facing the right direction.

7. Before applying any Assembly Grease, use some Plastiguage to make sure the bearing clearance is correct. Then apply assembly grease to the CLEAN bearing surface and tighten the bolts to spec.

8. Put the oil pan back on with a NEW gasket and tighten down the motor mounts if removed.

CLEANINESS in this procedure is extremely important!! Use plenty of parts cleaner and an air nozzle if possible.

Really The BEST thing to do is to pull the entire motor and do a rebuild. You might end up doing it anyway later! You can pull the motor without the trans by removing bellhousing bolts.

Good luck! Email me if you have any questions. Mark.A.Flynn@intel.com