That's an odd wear mark, would assume you have matching scoring in the cylinder it came out of? Although in a pinch you probably could dress up that piston, I wouldn't reuse it. Especially since this engine has been gone through once already, Best advice I would give you is to clean up all the parts, take them to a machine shop and have them measure bores, crank journals, and rod big ends, plus check out heads before you order any parts. A decent shop will be able to tell you exactly what is past wear limits and correct size bearings etc you need. This far into it with an unknown history you might as well take your time and get it right
There is hardly any wear on the crank and the bores look good. A little shine on the side of the bores but nothing a little honing won't solve. The bearings looked good as well and it could have easily run another 100k without problems. Since im changing the cam and im in there I do all new bearings. If i take it to a machine shop, I might as well buy a short block from a marine super for 1200. The new parts run me $450 with the donor engine $225. I have access to micrometers and can check the crank if I want to but im not concerned with the wear. This would definitely show right now and it looks good. Will post a picture of the crank..
Not sure if I caused the scuffing. When i took out the piston, the top ridge of the cylinder wall wasn't cleaned. So there was carbon deposit that was pushed out when I pushed out the piston. I can't remember how much deposit was there. May that have caused this? That explains why there are no scuff marks below the 1st ring.
I measured the crank today and I'm within spec on the main and con rod journals. I took into consideration the undersize of .02" on the mains and .03 on the con rod journals.
Rod measured 2.2187-2.2192" stock is 2.2487-2.2497.
Main measured 2.4280-2.4285" stock is 2.448-2.449".
Carbon wouldn't make those marks getting a piston out of the bore. If it's not scratched in the bore the piston must have been that way when it was put in.
.030 seems like a big undersize on the crank. I don't think I even had to do that much grinding rebuilding a chevy V6 with a spun rod bearing. As long as your confident in your measurements should work out.
Yup. I started out as a mechanic assembling machines and now have an engineering degree. I worked on a Honda cb550 from 1977 and rebuild the engine. Only put new rings in since everything was still ok.
I'm just running into new things with every thing and like a second opinion.
the piston skirt looks good. It's just the top ring to the side. Maybe something got it there and scuffed it
Cleaned up the block some more. Have to get the other freeze plug out to get the other cam bearing out. The bores cleaned up ok I think. Some shadows on the top. I don't want to hone too much. Only to get new cross hatching in and deglaze it.
Ok. I started to take the mercruiser apart. The starter wheel is much thicker than the the donor engines. I thought that the rotating assemblys need to stay together. Will,this be a problem if I use the starter wheel on the new engine?
That's a flex-plate, for an automatic transmission, not a flywheel (automatics use a flex-plate that the torque converter bolts to. Manuals use a flywheel that the clutch assembly bolts to). I think you said both blocks are non-balance shaft, so the flywheel should fit onto the crankshaft of the engine you're using. I would take the whole rotating assembly (Crank, pistons and rods, flywheel, harmonic balance) to a machine shop and have them balanced.
Don't throw away the flex plate. They crack more often than you might think and folks need replacements. You may get a few bucks for it. Well,,, maybe not for a V6, but what do I know ;-)
