Block Has Been Bored .030 - Is it Toast?

Block Has Been Bored .030 - Is it Toast?

Joined: August 4th, 2011, 9:37 pm

September 4th, 2011, 6:12 pm #1

I'm building a 1970 Mach 1 Mustang restomod. I recently pulled the 351C 2V motor and popped off one cylinder head. The piston tops are stamped "03". I assume this indicates the block has been bored .030 over. Each cylinder has a small ridge at the top; just enough to catch my fingernail. (Previous owner claimed the motor has about 50K miles since the rebuild, whatever that's worth.)

I was hoping to build a performance street motor using this block. But if it's already been bored .030 over, is it toast? I've read and heard a Cleveland block shouldn't be bored more than .030 over. But I don't know how hard and fast this rule is.

So, might it be possible to hone the cylinders and be good to go?

Or, might it be OK to bore it just slightly larger for a performance street engine?

This is the original block and I'd really like to put it back into the car.

Thanks in advance!
Last edited by ColoradoKlutch on September 4th, 2011, 6:18 pm, edited 1 time in total.
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Joined: February 28th, 2008, 4:15 pm

September 4th, 2011, 6:30 pm #2

You can get .040 pistons and I have run several blocks like this.
Andy
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Joined: May 20th, 2005, 4:48 pm

September 4th, 2011, 6:32 pm #3

I'm building a 1970 Mach 1 Mustang restomod. I recently pulled the 351C 2V motor and popped off one cylinder head. The piston tops are stamped "03". I assume this indicates the block has been bored .030 over. Each cylinder has a small ridge at the top; just enough to catch my fingernail. (Previous owner claimed the motor has about 50K miles since the rebuild, whatever that's worth.)

I was hoping to build a performance street motor using this block. But if it's already been bored .030 over, is it toast? I've read and heard a Cleveland block shouldn't be bored more than .030 over. But I don't know how hard and fast this rule is.

So, might it be possible to hone the cylinders and be good to go?

Or, might it be OK to bore it just slightly larger for a performance street engine?

This is the original block and I'd really like to put it back into the car.

Thanks in advance!
....is to tear it down and have the cylinders sonic tested. It depends on how bad the core shift is on the block and how bad the ridges are. It would be hard for any of us here to say a 'yes' or a 'no' without seeing it or testing it. It could be possible that a good torque plate hone job would clean everything up and you could buy some different pistons depending on what the bore came out to be. It also could be possible that it's already past its limit.

Brent Lykins
B2 Motorsports, LLC






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Joined: August 4th, 2011, 9:37 pm

September 4th, 2011, 7:11 pm #4

I'm building a 1970 Mach 1 Mustang restomod. I recently pulled the 351C 2V motor and popped off one cylinder head. The piston tops are stamped "03". I assume this indicates the block has been bored .030 over. Each cylinder has a small ridge at the top; just enough to catch my fingernail. (Previous owner claimed the motor has about 50K miles since the rebuild, whatever that's worth.)

I was hoping to build a performance street motor using this block. But if it's already been bored .030 over, is it toast? I've read and heard a Cleveland block shouldn't be bored more than .030 over. But I don't know how hard and fast this rule is.

So, might it be possible to hone the cylinders and be good to go?

Or, might it be OK to bore it just slightly larger for a performance street engine?

This is the original block and I'd really like to put it back into the car.

Thanks in advance!
I understand there's no way to tell for sure without a machinist checking the block. But I wasn't sure if it would even be worth having it checked if there was simply no way to save a block already bored .030.

Nice to know it's possible to run a .040 bore or maybe to even hone the cylinders. The machine shops in my area seem to be Chevrolet-focused. I'm not sure I can rely on what they might say about a 351 Cleveland.
Last edited by ColoradoKlutch on September 4th, 2011, 7:21 pm, edited 1 time in total.
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Joined: May 20th, 2005, 4:48 pm

September 4th, 2011, 7:29 pm #5

...it could be perfectly fine and ready for another go-around.

Even if they are predominantly Chevy shops, they should be able to give you a good professional account on how thick the walls are (with a sonic tester) and how straight the cylinders are.

Brent Lykins
B2 Motorsports, LLC






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Joined: June 17th, 2010, 12:57 am

September 4th, 2011, 7:34 pm #6

I understand there's no way to tell for sure without a machinist checking the block. But I wasn't sure if it would even be worth having it checked if there was simply no way to save a block already bored .030.

Nice to know it's possible to run a .040 bore or maybe to even hone the cylinders. The machine shops in my area seem to be Chevrolet-focused. I'm not sure I can rely on what they might say about a 351 Cleveland.
if in colorado where at?
Last edited by pewterboss351 on September 4th, 2011, 7:34 pm, edited 1 time in total.
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Joined: August 4th, 2011, 9:37 pm

September 4th, 2011, 9:48 pm #7


Hi Bill. I'm in Colorado Springs.
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Joined: June 17th, 2010, 12:57 am

September 6th, 2011, 2:57 am #8

I thought there was a ford specality shop in colorado springs
thats builds boss 429's with kasse heads? or is that just someone jumping on the kasse head bandwagon?
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Joined: August 4th, 2011, 9:37 pm

September 7th, 2011, 12:06 am #9

I don't know, Bill. I've heard recommendations for Geddes and Lee's for local machine work. But I don't think either shop specializes in Fords.
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Joined: April 18th, 2008, 5:09 pm

September 7th, 2011, 6:10 am #10

I suggest Dennis Quella's Pantera shop in Castle Rock. Its 100 miles or so North so he's not quite in your back yard but Dennis has built more Clevelands than most of us have ever seen. He currently has three engines in work including one Fontana stroker he's finishing up. It'll be worth the trip, I think. Try contacting him at www.panteraperformance.com
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