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Cylinder Rust

4K views 5 replies 5 participants last post by  richard stewart 3rd 
#1 ·
Hey,

I don't post here much at all, but I frequently lurk around searching for info.
I recently picked up an early 350 block that was cleaned up, decked and bored .030 over by the previous owner some 10 years ago. It sat in a warehouse since, slowly eating itself away. :(

So he doesn't remember exactly what was done, but it was clearly cleaned & machined, and a quick check with my calipers shows a 4.030" bore.

Since it was sitting in an uncontrolled environment for SO long, the surfaces started to rust and pit. I cleaned it up with some lube and scotchbrite pads, but some of it is bad. Please look at the following pics and let me know what you think.

http://picasaweb.google.com/Michael.G.Hartman/1967ChevyCamaro

Please pardon the messy garage!!

Should I send it to a machine shop for evaluation? Do you think honing will clean it up. I can borrow one if it will work? Or would opening to .040 or .060 be the better route??

A machinist friend of mind also insisted that each bore had to have been machined with a SPECIFIC piston in mind/in hand. Since I just have the block and no pistons, it should be re-machined or spec matched to whichever pistons I eventually purchase.

I'm an engineer by trade but a total newbie to engine design and building.
I'm also planning on chasing all the thread and going at all the passages with a wire brush, smoothening the oil return holes and slapping a coat of hemi orange on it. Maybe even some of that insulation paint under the timing cover and intake 'valley'.

Thanks,
Mike
 
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#2 ·
Measure the bores with an inside micrometer to make sure they are exactly 4.030, run a dial bore guage down each one to make sure they are straight top to bottom. From what I see in the photos I wouldn't be afraid to use the block as is. Pistons are spec'd by their manufacurer for a desired clearance and depending on what brand you choose this will vary from .0005-.006
Piston manufacturer's usually machine the pistons so when fitted to a perfect 4.030 bore the clearance will be right but you really should measure them and check for yourself just to be sure-I've seen some that measure inconsistantly and that's when you need to bore the block to fit the piston or return them for a better quality set. Bob
 
#3 ·
Just by looking at pictures it`s difficult to tell. From what I seen it didn`t look bad, some rust flashing is still visible but will come off quickly once the piston rolls over it a few times. I would check to see if it would hone out. But if you want piece of mind, take it to your machanist, if it can`t be honed out, then I`m sure .040 will clean it up. Pits are usually just that, pits in the bore surface, I`ve seen them so deep they found water and I`ve seen them so shallow we still used the block.
 
#4 ·
Thanks for the responses!

I'm pretty confident that a fresh honing job will clean up most of the rust. Though it's not so much rust, as it's all black in color. None of it is surface rust, I've cleaned all of that up already. Seems more like voids of missing material.

What I'm worried about is the deep pits in a couple of the cylinders, that I can easily feel with a finger nail. Especially the last pic and the voids in the chamfer at the top of most of the cylinders. I've heard that if you can feel it with a nail, it has to go. I guess I don't have to worry about the rust at the top of the cylinder since the rings don't go that high, but I haven't found out how high is high.

I'm looking to get 450+ ft-lb & hp out of this motor so I want everything perfect. And the last thing I want to do is slap it together and end up with poor performance or an oil burner.

I guess I'll finish cleaning it up and haul to my machinist. I need cam bearings installed anyway. I'll probably borrow a bore gage from work in the mean time.

Thanks again,
Mike
 
#5 ·
MadPower said:
Hey,

I don't post here much at all, but I frequently lurk around searching for info.
I recently picked up an early 350 block that was cleaned up, decked and bored .030 over by the previous owner some 10 years ago. It sat in a warehouse since, slowly eating itself away. :(

So he doesn't remember exactly what was done, but it was clearly cleaned & machined, and a quick check with my calipers shows a 4.030" bore.

Since it was sitting in an uncontrolled environment for SO long, the surfaces started to rust and pit. I cleaned it up with some lube and scotchbrite pads, but some of it is bad. Please look at the following pics and let me know what you think.

http://picasaweb.google.com/Michael.G.Hartman/1967ChevyCamaro

Please pardon the messy garage!!

Should I send it to a machine shop for evaluation? Do you think honing will clean it up. I can borrow one if it will work? Or would opening to .040 or .060 be the better route??

A machinist friend of mind also insisted that each bore had to have been machined with a SPECIFIC piston in mind/in hand. Since I just have the block and no pistons, it should be re-machined or spec matched to whichever pistons I eventually purchase.

I'm an engineer by trade but a total newbie to engine design and building.
I'm also planning on chasing all the thread and going at all the passages with a wire brush, smoothening the oil return holes and slapping a coat of hemi orange on it. Maybe even some of that insulation paint under the timing cover and intake 'valley'.

Thanks,
Mike
I can't really see enough detail to make a for sure statement of going ahead and using it. For what it's worth, I'd take to a competent shop to have it magna fluxed or dye penetrated to check for cracks, if OK have the main saddles checked for alignment no sense in spending money in other places if the bearing bores arn't yet straight, have the deck checked for flat, the usual machinist stuff to see if it's worth going further. If otherwise good, I'd have rebored just enough to clean it and select pistons from there.

For a street engine, there isn't a need to bore the engine to each specific piston dia, if it's going racing that kind of attention to detail is worth a little power and reliability, but for the street it's not necessary.

Bogie
 
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