Thread: Big Problem? (Machine work)

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Well, here's the deal. I took an old 350 I had into the machine shop to have them replace cam bearings. I wasn't praying for much, but I wanted something to get me by while I worked on aquiring a good motor. It just so happens that the previous machinist (Who, mind you, has quite a name for himself) had built a motor two years ago, as a personal project, and when he was done he oiled it and covered it, wrapped in plastic in the back of the shop.

The next day my machinst calls, telling me about how much wear is in the motor I brought down to him, and asks me to come take a look. I hadn't realized how many miles were on the block, but from the look of the bearings and cylinder wall wear, it was rather high. A ring on #3 was shot as well.

He showed me the motor that the previous machinist had built, all bored, surfaced, balanced, and assembled with great care. The shop owner and I go back (I fixed his computers at the shop when I was younger) and he offered me a great price on the motor "It's not doing me any good sittin' there" and the ability to make payments on it. Great sincere guy. The machinist and I look over the block, check casting numbers, and look at the paperwork for it. It was a very well built powerplant that was pieced together with care.

--guts of the question--

Well, I brought the motor home after making only a small down payment (This was yesterday) and today, when looking over it in more detail, noticed that there is some rust (very shallow, but enough that oxidized iron came off on my finger when rubbed across) on the top 1/8" of one lifter bore. maybe 60* around. All in all, about 1/4 of a square inch of rust where the oil may not have stayed put. This probably went unnoticed as the motor sat covered for over two years, but enough to do long term damage.

I understand that this is a very clearance-crucial area, and that the integrity of my valvetrain rests here. Is this machinable? Can this be repaired? or is this block hosed? It's such a well built motor that I'd hate to sacrifice it for want of a 1/4" patch of rust.

If pictures will help illuminate this issue, I will be happy to take some.

I finally thought I had found a good motor...

- cliffnotes -
Can a small area of pitting rust be machined from a lifterbore without compromosing the lifter integrity?

well some pits will hold oil and not do much there . but there can be no hi spots. the lifters bores . they need to spin if flat lifter type cam i run a reamer thru the bore and a brm ball hone this will take out the hi surface rust but the block will need to be wash and resemble and all ways check to make the sure all the lifters turn easily in the bores

With out seeing it I'd be hard to say, But if it were mine I'd probably clean it up and run it. I have never heard of anyone overboreing and sleaving for a lifter bore.

the bores on some of the gm blocks are very ruff stock and i have made iron sleeves and put them in blocks stock bore size and gm sells them to but it would have to be very bad bore to warrant this . i have had races block with bronze bores sleeves in them to . i would like to see it. but i would say it is not that bad like i said the lifter just need to turn in bore

Working on getting a digital camera, I'd like to think I'll have pictures by tonight. The other bores are in great condition. I'll update soon.

I have to agree, if it was my engine I would take a scuff pad soaked in oil and just clean it up and run it as is. You would be amazed at the inside of certain engines even when brand new that last 100,000 miles.

Added pictures, see first post.

From what I see I'd still clean it up and run it.I everything else is assembled take it apart clean it and run it. It looks like its just at the top of the bore.

use some 120 grit wet dry only wet with WD40 paper and sand with your finger till you can turn lifter if you can not hook your finger nail in the pitts you will be ok if you put a paper towel down past the rust and put on a engine stand upside down you will sand this over head. the junk will fall to the ground and what will not will get trap in the sand paper and in the paper towel make a plug with the paper towel make sure the oil galley get block by the paper towel plug

Thanks alot folks, I was sweating bullets. I just finally have a decent motor in my grasp, and I thought we were rolling into some hard times here.

I've run worse, but with solid roller. I agree with the others, just lightly sand the lifter bore. Don't try to remove the pits because you will get it out of round. Just get the high spots down and check it with a lifter.

I don't recommend this but I have seen a friend use epoxy in them and hone them back out with a brake cylinder hone. I've also heard of using epoxy in the cylinder bores to fill in rust pits. Hmmm, backyard rings a bell.....

I spoke with the machinist today, and brough him a nice 4x6 picture of the bore up close (I love my photo printer, haha). He said that I should very very carefully remove the rust there, apply some oil, and check for high spots carfully. He said to use an old lifter to check out the bore and make sure that it rides smoothly.

Also, he said that he acknowledges the problem, I proved it by bringing in the photo, and if there is ever a failure due to that problem, I'm totally covered

I like doing business with honest people. So hard to find these days. Currently checking my spring pressure and looking over my Darts on the house

Thanks alot for your help guys, looks like I finally have all the pieces.

I agree with the sandpaper. Its not uncommon to see this type of surface rust. When storing an engine for long term like this one, take carefull measures and make sure every machined surface is well oiled. It also doesnt hurt to periodically check during the storage time.