The Stovebolt Site Forums The Shop Area Engine Shop Block cylinder rust?

Basically, I have a bare 350' engine block that has some rust inside the cylinders. What would be the best way for me to determine if the rust has penetrated the cylinder walls to a point where the block is ready for the junk yard?

A heavy load of spray soap like Simple Green and a ball hone. Spray the soap as you hone till the foam turn white and not rusty. Rinse, dry, and wipe with a wad of paper towels soaked in WD40. A large wire brush in a drill will also work, just not as fast as ball hone will.

When I start an engine build for customers, strip the block to bare casting, no plugs of any kind, then sandblast the block, wire wheel, cut off any flashing and soften the sharp edges, then degrease, then power wash, then hone, then power wash again before sending it to a machine shop. I have them jet wash it when they are done, then I wash again with degreaser and scrubber pads. I use commercial floor polish pads cut into circles clamped to a threaded rod spun in a drill to clean the bores after machining. I also use scotch bright scrubbing pads cut into pieces pinched onto long welding rods spun in a drill to clean oil rails and lifter bores. Every bit of the blocks has been scrubbed or wire wheeled before assembly. They look like fresh cast blocks when I start to assemble.

joe

I use an inexpensive bronze rifle cleaning brush and a cordless drill to clean oil passages in blocks and crankshafts, along with brake cleaner spray. A 20 gauge shotgun brush works well for the large oil passages for hydraulic lifters. A 55 gallon oil drum filled with water and sodium hydroxide drain cleaner (lye) and a heavy dose of laundry detergent, works well for big parts- - - -blocks, heads, crankshafts, etc. Build a fire under the barrel and boil it for a few hours. Just don't put any aluminum parts like pistons, timing covers, etc. in there- - - -they'll disappear!
Jerry

I've got a couple of steel bicycle frames with super stuck aluminum seatposts as the only thing wrong with 'em. Maybe I could use the lye to eat them away?

Probably- - - - -but it will also strip paint- - - - -particularly if you boil the solution. I'd suggest cutting the posts off and drilling or reaming out the remains of them. You could also thread the posts with a big tap and use a slide hammer to remove them.
Jerry

Now once the cylinder walls are all ball honed and cleaned up, am I now looking with a magnifying glass or something to determine if rust still exist, and how deep can I go before the block is junk?

It depends on the year of manufacture of the block. Somewhere around the middle 1980s, GM started making blocks with thin wall castings. Those engines could be rebored to .030" oversize without any problems. Earlier blocks from the late1960s and 1970s could handle a 60 overbore. There will be a casting date somewhere on the block. If only one or two cylinders have deep pits, repair sleeves can be installed, but the parts and labor cost gets impractical pretty quickly, especially since a 350 is a "belly button" engine- - - - -"Everybody's got one!" It's easier and simpler to fund a better condition block than shoveling money down a bottomless pit!
Jerry

It's unlikely its pitted unless it had pistons in it. The piston hold water in one place that forms the pits. Without pistons, the water runs through leaving just a surface rust.

I really want to save this here block as it is a 1969 4 Bolt main with a steel crank, and everybody doesn't have one of these!

Give the cylinders a good cleanup with a dingleberry hone, and then measure taper wear before you get concerned about rust pits. If there's over about .005" of taper, you'll need to do a rebore job and use oversize pistons. That will clean up all but the most severe pitting. A 69 block will handle a 60 over piston with no problems- - - - -I've run those blocks in 500+ HP round track applications at well over 7K RPM.
Jerry

Joe is absolutely right about a block with pistons in it trapping water. I just rescued two MOPAR 383 bare blocks that have been sitting out in the open, exposed to the weather for 15+ years. They both have surface rust on the cylinder walls, but no serious pitting. Both engines are going to get built up with 460+ cubic inches with .060" oversize pistons and 440 crankshafts, stroked an extra 1/4".
Jerry