Spun 360 Rod Bearing
I bought a used 360 w/ balanced stock rods and crank, KB191's (measured 10.9:1), 292* .508 purple cam, and ported 915's w/ 2.02 intakes. It has run mostly 11.90's in a 3000# (at the line) Duster.
I took it apart to see what was in it, and check it out when I bought it, because the guy I bought it from didn't know much about it. Everything measured good.
I put new bearings and rings in it while it was apart. (I ran a stone-type hone with Scotch Brite covering the stones through it.)
Anyhow, I put about 500 street miles and 18 1/4 mile runs on it, when I started hearing a knock at low rpms, and light load. Nothing at idle, nothing at WOT. Hoping it was a detonation issue, I retarded the timing, no difference. I cut open the oil filter and found some bearing material.
Pulled it out, and just finished looking it over. No other metal anywhere. All the other bearings look fine. The filter worked! But... number 8 rod has spun the bearing. (The oil pressure was always good, 50-75 psi.)
I'm not really experienced at engine diagnosis, but it doesn't seem too bad. The only bearing material missing is the tangs.
My assembly notes say that the crank is .010" undersize. Standard is 2.125, mine (on a good journal is 2.115, the spun journal is 2.114.
My questions:
-Is this something that can be polished to fit a .001 or .002 oversized bearing? (That's probably dependent on the machine shop's inspection?)
-Should they all be polished to suit same size bearings?
Oh, and I know the cause. A bit embarrassing. My assembly notes also mention questionable crush on the cap bearing insert. I guess I erroneously figured that, "It must've been that way before, so it should be okay now".
:BangHead:
I don't have any experience with the nearest machine shop. I'm going to stop by my DD mechanic's shop and ask him about them.
I was expecting the worst (ruined crank, total tear down, etc.), but maybe I got lucky. Maybe they can polish it up, resize the rod and send it. I really don't need to sink a bunch of cash into it.
I bought a used 360 w/ balanced stock rods and crank, KB191's (measured 10.9:1), 292* .508 purple cam, and ported 915's w/ 2.02 intakes. It has run mostly 11.90's in a 3000# (at the line) Duster.
I took it apart to see what was in it, and check it out when I bought it, because the guy I bought it from didn't know much about it. Everything measured good.
I put new bearings and rings in it while it was apart. (I ran a stone-type hone with Scotch Brite covering the stones through it.)
Anyhow, I put about 500 street miles and 18 1/4 mile runs on it, when I started hearing a knock at low rpms, and light load. Nothing at idle, nothing at WOT. Hoping it was a detonation issue, I retarded the timing, no difference. I cut open the oil filter and found some bearing material.
Pulled it out, and just finished looking it over. No other metal anywhere. All the other bearings look fine. The filter worked! But... number 8 rod has spun the bearing. (The oil pressure was always good, 50-75 psi.)
I'm not really experienced at engine diagnosis, but it doesn't seem too bad. The only bearing material missing is the tangs.
My assembly notes say that the crank is .010" undersize. Standard is 2.125, mine (on a good journal is 2.115, the spun journal is 2.114.
My questions:
-Is this something that can be polished to fit a .001 or .002 oversized bearing? (That's probably dependent on the machine shop's inspection?)
-Should they all be polished to suit same size bearings?
Oh, and I know the cause. A bit embarrassing. My assembly notes also mention questionable crush on the cap bearing insert. I guess I erroneously figured that, "It must've been that way before, so it should be okay now".
:BangHead:
I don't have any experience with the nearest machine shop. I'm going to stop by my DD mechanic's shop and ask him about them.
I was expecting the worst (ruined crank, total tear down, etc.), but maybe I got lucky. Maybe they can polish it up, resize the rod and send it. I really don't need to sink a bunch of cash into it.