Engine Assembly: Installing The Pistons

Next task on the assembly list was installing the pistons. First they needed to be ringed though. The ring gaps had been inspected so I got on with it. Oil ring assembly was first. They were made from spring steel so installation tools were not needed. I just spread the expansion ring and pushed it in the bottom groove. The side rails followed. I was not worried about the gap positions for now. I'll set them right before installing the pistons.

The compression rings are a bit harder so I bought pliers for them. They were only a few euros and made installing the rings really easy. I just had to make sure the moly faced ring was installed to the top groove and that they were installed the correct side up. This was indicated by a dot on both rings.

Then it was time to insert the pistons to their cylinders. Before the final install, I wanted to check the bearing clearance though. I did that only for the first piston as testing all of them would have been somewhat pointless. First the bearings.

Then pieces of rubber tubing over the bolts to protect the bores.

And installation. I had a cheap ring compressor that I screwed around the piston. I sprayed WD-40 on everything and then tapped the piston in. The compressor unfortunately got stuck a bit and broke as I pulled it out. So much for cheap tools. At least I got the clearance measured with Plastigage again.

As with the main bearings, the result was about 0.002 inches. Acceptable range should be 0.002 - 0.003 inches so I was fine.

I did some reading and apparently the best tool for installing pistons is a tapered aluminium ring that is precision tooled for a single bore size. So I went an bought one by Moroso.

You can only use it for 4.030 inch bore size but I don't think I'll be building another engine any time soon. After pulling the first piston out again, I prepared it and the crankshaft for final install. This meant spreading some assembly lube on the journals and bearings...

...then turning the correct journal to bottom dead center (BDC), oiling the bore, locating the ring gaps and using the tool to tap the piston in. For ring gap positions I used the ones instructed in Millers book.

I have to say that the installation ring was an excellent tool! I did not have a single problem with any of the pistons. They just smoothly slipped in the cylinders. I pushed the piston in until the bearing contacted the journal.

Final step before placing the cap on the rod was checking that the locating tab on all the bearing faced towards the center of the block.

This meant that the rod had been installed correctly on the piston. Everything was OK in that front so I torqued the cap nuts to 24 ft-lbs. And after a few hours of work, all the pistons were in!

Turning the crank was naturally much harder now but everything still moved smoothly so this job was done!

Disassembling The Engine Part 2

Finally it was time to drop the crankshaft. Everything around it had been removed so I could get it out of the engine. First I had to remove all the connecting rod caps. They are attached with just two nuts so I removed them and pulled the caps. I stored them in order so I can put them back in the same positions.

Next I loosened the main caps and made sure the crank came down with them. Finally, very carefully, I removed caps and took the crank down.

It was time to check the damage. The crank journals seemed pretty good and only two had some small scratched that I could feel with my finger. Hopefully I can just have it polished and put it back.

The bearings had taken most of the damage. Here's a photo of the mains.

All of then have worn down to the copper. No wonder the oil pressure dropped a bit when idling. The rod bearings were not much better.

So now everything necessary has hopefully been taken off the engine so I can service the parts and start putting everything back together. We'll see how that goes. I'm especially nervous how I can get the crank back in and attach all the connecting rods...