Technical Chevy Crankshaft grind marks

I wondered if anyone on this site knew what these marks are that I found on my small block? The engine is from a 57 chevy, but it is not original. The crank is from a late 60's 327. I was told that this was done to help keep a rope seal soaked in oil? Anybody seen it?

 

yes I've seen it. I think it's original.

 

I think they are to work somewhat like a fan or impeller and draw the oil back into the crankcase...

 

thats GM original, several divisions beside chevy had them, only on the rope seal cranks helped keep a little oil on them so they would stay swollen and sealed and help lubricate the BAd fibre that was in it ( man I miss them good old rope seal with that stuff , nothing new is close other than a neo lip seal . when they started to go neoprene that disapeared , the shops I dealt with ground them off and polish it out if a neoprene seal was going to be used as it would chew it up in a month or so . .

 

but I would not expect to see it on a 327 crank....the rope seals were used through 1959(?).

 

Squirrel, I think your right. It's hard to mask an early motor with block numbers and no side mount bolt bosses however you can say it has anything inside it you want. Kind of like all 350's are 4 bolt main steel crank motors until you take them apart. My guess would be that crank is the same one that 283 left the Factory with.
The Wizzard

 

It hasn't been established what block and crank is in the car. The OP only mentioned that the engine is not original to the car.
If the engine is still in the car then I would get under the car and while the crank is rotated slowly look at the flange on the end of the crank. If it is completely round then it is a 283 crank and not a 327 as was thought. It could very well be a block with a suffix that ID's it as a 327 but the crank may be from a 283, making the hot rodders old favorite 4" bore X 3" stroke 301.

 

OP says the crank is from a late 60's 327 in his post. Correct me if I'm wrong, but weren't the later 327's large journal, while the early 327/283 were small journal? If it were a later crank, it wouldn't have the marks for the rope seal on it right?


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You are correct in saying that late cranks ('68 and up, the exception was the '67 350 in the SS Camaro) are large journal, but I'd still look at the crank flange to verify what crank it is. If it is completely round it is a 283. A 327 crank will have a notch that will be around the 1-2 o'clock position when the flywheel dowel is at 6 o'clock viewed from the engine side.
Just like "all SBC's are from Corvettes" any small journal SBC could be called a 327.

 

I will post the crank casting number when my engine builder sends it to me, but we are getting a quote to polish out the marks as it did chew up my seal and started leaking.The seal was destroyed.

 

Looks to be a notch in flange.

 

Yep, looks like a notch, didn't notice that before. Good catch.
And actually it was the 302 crank with one notch, the 327 has two. Memory lapse, CRS.

 

I've seen those same 'knurls' on SBF cranks (pre one-piece seal versions), and to my knowledge they always used a rubber seal.

 

OK, here are all the numbers:
Crank: 3932442
Block: 3970014
Heads: 3795876
Seems like a mix of vintages.....thanks for your help with this.

MGTSTUMPY I did not notice the dent, looks like it might have been dropped...this motor is from my 57 Chevy. I know it is not a match for the car. I had a major oil leak, and we are installing a new seal and checking things out too ensure that all is good with the motor. Plan is to polish out the marks if possible.....

 

I checked the numbers and it comes back not quite as represented-
3932442 crank casting could be machined for a 267, 305 or 350,
3970014 block is a 350,
and I didn't find 3795876 head castings, but there was a 3795896 used as early as 1958 and as late as 1972 on 283-307 and 327's that have 60 CC's with 1.72/1.5 valves.

 

According to Best gaskets sbc used rope seal through 58. I do recommend their seal.