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Crankshaft prep

Paul_G

Paul_G

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I am rebuilding a 383. The crank still has STD bearings in it. There is some scoring on the journals. Lines I can feel with my finger nail. The rear one is the worst. I went over them with some 1000 grit paper wetted with WD40. They came out pretty good except the rear one, it still worries me.

A friend has a 383 crank that's been standing in his shop for many years. It was cut 10/10 installed in an engine and never used. He pulled it, put white grease on the bearings and journals, taped the bearings in place and it has been standing ever since. I bought it. The grease has turned to hard paste on the bearings, the masking tape has turned hard and the glue is stuck to the bearings.

The crank is good, journals look nice. One main bearing fell off and he cant find it. So need a set of new main bearings since I don't see them sold separately.

The grease is caked to the bearing surface on all the bearings. it wont come off just rubbing with a rag. Is it advisable to soak the rod bearings in WD40, brake cleaner, or gasoline to loosen the hard caked grease?
 
Never have liked using gasoline as a cleaning agent since it has a really low flash point but if you're sure there's nothing around that's going to create an ignition source including a cig, then go for it. Some brake cleaner is highly flammable too.
 
Have you measured the journal that you don't like? If its round with no taper a groove or nick won't hurt anything.
Doug
 
Kerosene, mineral spirits and naphtha which you can get at Home Depot are good cleaning solvents and safer than gasoline. Just get a large plastic tube so you can brush/pour the cleaner on. Use nylon brushes to avoid scratching the journals and get the oil passages clean. And then a wipe down with WD-40 so you can measure the journals with a micrometer. You need the journal OD and the ID of the mains to know what size bearings you need. Clean up the current crank and measure it. Forged 383 cranks that can be ground -.010 or -.020 are good cores.
 
Parts cleaner solvent is available at Fleet Farm(or similar), expensive but safe.
Edit: a new main bearing set is not that expensive.
 
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Before I installed it in my engine I would take it to a reputable engine machine shop to have it Magna-fluxed checked for straightness and have the journals measured and polished to verify the proper bearings needed.. The crank is the heart of the motor.
 
Take it to an engine shop and have them put it in their caustic tank , Caustic will remove all that crap and save you a ton of work and it will look like new.
Then do what MoparLeo said
 
I put many hours today in to cleaning up the crank. I put a set of bearings in a rod and test fitted it on the journal. It fit looser than I would like. I have a digital calipers and measuring tools. Great time to use them.

The rod journal stock to the best of my knowledge should be 2.374". Mine measured 2.366".

The bearing clearance should be .001" per each 1" diameter of the journal. Comes out to .0023" bearing clearance for oiling, add that to the journal diameter, comes out to 2.368". 2.368" should be the measurement inside the bearing when tightened on the rod. Mine measure 2.373". .005" too loose. They are sloppy.

These bearings were with the crank. They should have been the right ones. But I dont think so. Do I have it right or am I screwed up?
 
You can’t accurately measure bearing clearance with calipers. You have to have a mic and a bore gauge. I was a machinist and am damn good with calipers but would not trust them for that type of measurement. Platigauge would be better in that case. You could also get much closer with a snap gauge and mic.

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I ordered a new set of King bearings from Summit, .010" under sized. Both rod and main.
 
Paul, BTW I don't think you need to mag the crank. Stand it on end with all the bolts out, no damper bolt, tap each counter weight with a hammer. If it rings like a tuning fork you're good. I know this from my days when I severely abused (7000+ RPM) stock 440 steel cranks in my drag motors. If they don't sound like a tuning fork, no good.
 
66Satellite47 said:
Paul, BTW I don't think you need to mag the crank. Stand it on end with all the bolts out, no damper bolt, tap each counter weight with a hammer. If it rings like a tuning fork you're good. I know this from my days when I severely abused (7000+ RPM) stock 440 steel cranks in my drag motors. If they don't sound like a tuning fork, no good.
Click to expand...

They all ring when tapped.

Got the new .10/.10 under bearings. Test fitted to the crank and they are perfect. Crank and pistons are installed. Now it is a short block. Soon as the rear main side seals show up the bottom end can be finished up. Just need to decide on the cam I am going to use. .
 
The engine is together and in the car. Broke in the cam this morning. Checked for leaks, put through a few heat cool cycles and everything is good. Went on a 30 mile drive, came home and changed the filter.

One thing I ran in to. The pilot bushing hole in the crank was not machined for the pilot bearing. I called a machine shop and... can not be bored with the crank installed. A friend down the street has a lathe. He put the new pilot bushing in the lathe and machined it down to fit in the crank. Problem solved.

And one more thing, The threaded hole in the 68 block for the super long power steering mount bolt is tapped for 7/16" bolts. My pump and brackets need a 3/8" tapped hole in the block. Came up with a hillbilly fix. Took a short 7/16" bolt, cut the threads off about 1/2" long and ground a taper on the cut end. Got another super long 3/8" bolt and cut the hex head off and ground a taper in it. Welded the two together. Screwed the 7/16" threaded end in to the block, assembled the pump and brackets over the rest of the bolt which is 3/16". Used a nut and washer on the end, problem solved.
 
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