390 Motor Block Repairs - 1964

[Rick Fullmer]

I have motor block cracks in the valleys around the lifters. Has anyone successfully welded repair block cracks?

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[Jim simone]

Is it a true crack or just casting mark sometimes it looks like a crack

 

[74 Harley]

If you aren't loosing coolant it's probably not cracked. I agree with the above it's probably just casting lines.
If it is cracked it's not worth repairing.
You can have it Magnafluxed to be sure.

 

[Rick Fullmer]

It’s at an out of state motor shop in WY, so I assume they know for sure. Trying to figure out if it’s worth keeping the original motor. I’ve already committed to a new block. I know you can stick weld cast steel.

 

[74 Harley]

Cast steel is not hard to weld. But blocks are cast iron, and yes it can be done but process is a little more difficult. Usually that means very expensive. 390 blocks are not that hard to come by.

 

[74 Harley]

Ask them if they Magnafluxed the block, that is a very unusual place for a crack without seeing moved metal. Freeze damage is the only way and I am just not seeing real evidence...

 

[Angry Bird]

I had a mechanic tell me that my block was cracked when it was actually a head gasket many years ago. He bet me the cost of the magnaflux that it was cracked.........it wasn't. A new head gasket (1969) and no problems since. I agree with all of the above comments this is a very odd place for a crack.