I am working on my new engine, and today I was getting things cleaned up ready to put the pistons and rods together and start the reassembly process. I have had the pieces for years, after having gotten sidetracked after I bought them but before I had a chance to do the build. So, I was just playing around trying to see how things would fit with the machined block and the various pieces. As part of it, I attempted to slide the piston into the cylinder...and it wouldn't go! This is a forged TRW piston, casting number 255-98, which theoretically means that it is an 0.030" over piston for a 302. My machinist bored the cylinders of my 302 out to 0.030" over, so I am certain that the dimensions of the cylinder walls are correct. Also, I have an old 302 A4 four bolt main block that is bored 0.060" over, and the piston won't easily slide into that cylinder, either.
Are forged pistons just larger than normal pistons? Do they run tighter clearances? I already put a small scratch in one cylinder wall, and I don't want to damage the block, since it is all set up and ready to go, so I am reluctant to try and force it in.
Frankly, I am mystified about the whole thing.
David
Are forged pistons just larger than normal pistons? Do they run tighter clearances? I already put a small scratch in one cylinder wall, and I don't want to damage the block, since it is all set up and ready to go, so I am reluctant to try and force it in.
Frankly, I am mystified about the whole thing.
David