Take a look at these pictures and tell me im wrong. To me it looks like the weight broke and someone ground it down. You can see blueing where it was ground. To further my theory there was a hole in the oil pan that somebody patched(poorly) The car only has 54k miles. The rest of the inner workings look mint. My father believes this was done at the factory to take weight out of the crank for balancing. And that the hole in the pan was something else. This engine hasn't ran in decades. Someone had it apart and put it together using grade 12 bolts on the head and black silicone on the oil pan. The oil in the case looked like it was put in yesterday... Sent from my SAMSUNG-SM-G891A using The H.A.M.B. mobile app
Maybe they hit something that squashed the pan. Spinning crank beat it from inside. That would explain both things. Sent from my SM-S320VL using Tapatalk
Heres the thing though. Under that weight is a massive sump. There are no marks on either top or bottom of that.
Not sure of the scenario but it's not factory. GM did not number connecting rods nor grind on a counterweight for balance. Also, bluing on the grind? Nope and nope. I've seen some hack jobs from GM over the years but not like that. Only idea I have is that someone dropped the crank during the rebuild and ground the burr off of it. And grinding a corner off to balance it would be a very inexact way to reduce the weight not to mention off center like that possibly leading to a stress crack. Or maybe there was a crack there on the counterweight and they ground it out? A possibility not to be overlooked. Not how I would have done it though.
Maybe, possibly, coulda, perhaps, at first glance, apparently, most likely, perhaps, conceivably...and perhaps, many more adverbs. Looks rough in any case. Mike
I don't think the engine plant would have taken a obviously damaged crankshaft to a grinder during assembly either. More likely it would have been tossed on a scrap pile and another crank substituted for it. Alone just taking it to a grinder and then having to clean the grinding residue off of it would take more time effort and money than tossing it and grabbing another. Production is all about pushing it down the line as quick as possible.
I wish i noticed this befor i put new rings in it. This car was last on the road in 1966. We've established its been worked on after production. Im looking at the grind marks and they are all going the same direction, as if this was done using a belt sander of some sort. Could this be done in the 60s as a balancing process? Or is this somebody fixing a fuck up? What happens if i run it like this?
Sitting at a stop light, dropped a rod, hit the crank, hole in oil pan. had rebuilt, sleeved block, ground damage off crank, reassembled, sold on used car lot to little old lady.
Magnaflux if you are concerned. SWAG (scientific wild ass guess) is that it will run fine as it was put together and ran that way before. I've never seen anyone balance a crankshaft by grinding it like that, the drill holes evident there were used to lighten it and using heavy (Tungsten?) to add weight in the same holes. Again, no expert just a ex-parts guy that put a few car and bike engines together over the years.
I agree to the above comment .....If you did not see anything worn out or hacked when you had the pistons/rods/bearings, out for ring replacement.......run it. If you were building a coast to coast driver, then perhaps worry. .
If the grinding was done by the crank when it was turning I would think the grinding would be circular with the center of the circle being the center of the crankshaft.
Oil pan could have been replaced along with whatever damage was done if the spinning crank was hitting something. Back in the 60s people were not as diligent at making professional repairs on used cars.
That’s it. The sump was replaced at the same time the pan was fixed. Back in the day mechanics “ fixed “ what they could, replaced what they couldn’t fix. The pan would have been an easy fix. Smoothed the marks on the crank out, sent the engine down the road. Bones
If it was ground that much to fix some damage, it would be way out of balance. I would not run it unless I had the crank re balanced.
My penny's worth... To start over, what is this motor in, what's it worth, are you going to keep it...etc. I've never done a patch job on a motor. Either rebuild it properly or not. I always would pull a motor, disassemble, take block, crank, rods to a machine shop. Then new everything, bearings, pistons, cam, lifters, etc. Block hot tanked, bored, crank turned & balanced. After reassembly a new engine. That one of course new oil pan. Sent from my SM-S320VL using Tapatalk
The Jalopy Journal
