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Hey guys, finally got the IDI torn down and am doing an inspection of the main bearings. Here is what I am seeing... What do you think? I was really only wanting to do gaskets, but the shape of these looks like a whole bottom end may be necessary as well.
1-4 look alright. #5 is not the end of the world but warrants replacement while it's apart. The cost is in labor, your time. Bearings are cheap. Replace the bearings and polish the crank or turn it if it's bad.
Back in the day a polish on the crank put you in pretty good shape, I would try to find the finest emery cloth you can, imho when it comes to main bearings, piston rings ect, you get what you pay for. Shop around online at places such as rockauto or ebay if you're on a budget but don't want to buy junk, maybe you can find a good deal. Every now and then I'll see weird stuff like a set of std bore pistons going for half what they are new and stuff like that..
Not sure what you're thinking on rings but that would be the first thing I change!
Bearings are cheap, i went with King, read good things about them. Supposed to last longer, and theyre an aluminum alloy that is supposed to last longer and polish a steel crank. Make SURE everything is spotless when installing bearings. Do not lube the backside of the bearings. I wiped everything down 3 times with brake cleaner and a new towel each time. Your cylinders you want to keep wiping with a new towel until the towel is clean after wiping. Torque 3,1,5,2,4 main cap order in 3 reps. I think to 90 ft/lbs but i would check. I got my rings, bearings, and pistons off ebay, with the exception of the gapless 2nd rings. Remember, cleanliness is godliness. I like steel wool for polishing journals, if theyre scarred, you can hit em with some fine emery first. I would also bar hone the cylinders at minimum.
You should at minimum "freshen it up" while you've got it apart. That's main and rod bearings, rings, gaskets. If you can't catch a fingernail on any marks on the crank jounrals that's good enough. If you can, you need to evaluate if they can be polished or if it requires turning. You can polish yourself as DarkOverCast mentioned. If there are any nicks you need to ensure there is no raised area that can damage the new bearing, small divots that do not run the circumference of the journal are essentially cosmetic as they will fill with oil while under pressure. Plastigauge the bearings upon install.
At minimum run a hone (3 stone drill type) through the cylinders to clean them up and and have a good surface for the rings to wear into. You should measure taper to determine the viability of the bore. .007" is maximum (and really pushing the limits if you want the engine to last long before bad blowby) You'll need a cylinder bore gauge for this. You can go a bit heavy with the hone towards the bottom of the cylinder to reduce taper.
Remember, parts are cheap compared to the inconvenience of having to pull the engine again, and maybe a long tow as well.
