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I am rebuilding a Ford 1320. I am going with new pistons that are .020 over standard. My question is, "Do I have to get the block bored out or can I hone the cylinders to get them within the .020 specifications below." (I don't want to pull the block unless absolutely necessary.)

ACTUAL MEASUREMENTS
BORE:
1st Cylinder ---- 3.230 in.
2nd Cylinder ---- 3.220 in.
3rd Cylinder ---- 3.220 in.


MANUFACTURER SPECIFICATIONS
BORE:
Standard ---- 3.228 - 3.229 in.
.020 over --- 3.236 - 3.256 in.

Any suggestions or information would be appreciated.

Thanks,
Mike
 

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You would be spending a lot of money on wearing out hones and still not get a true straight bore job. Some shops have or used to have portable boring machines that can rebore without removing the engine. Call a few machine shops and ask if they have or know of any shop with this service.
 

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Well lanranger.... according to your measurements the wear in the cylinders #2 and #3 is about .008 to .009 under the manufacturer's specs for the original bore... i.e. you may have miss measured the bores! If the engine was well worn and needed to be refitted with pistons and rings... it would not be "under" the original bore size!

Now that said...... I used to do a lot of machining on engines (old tractor engines and automotive engines). I have bored many engine blocks.... it takes a tremendous effort to hone a cylinder .020 overbore and keep the alignment and shape of the cylinder from being skewed!!! {I hated even finish-honing a cylinder the last .003 after boring them!) And to bore a worn engine to .020 overbore...... is extremely hard to do! We would always bore to the .030 overbore size, because .020 would barely clean up the cylinder on most car engines.... and on most tractors .020 would not be enough to clean most of the engine's cylinder walls. On .020 overbore you are only removing .010 off the walls of the cylinder.

If you are going to use the .020 overbore pistons... be careful using a portable bar.... one mistake and you ruin the entire engine (example: Didn't tighten the hold down enough)! Any boring bar can be tricky... and to learn on a rare or antique engine is not the thing to do! Better yet hire someone that is insured and knows what they are doing!
 

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I honed .020 on a 46 Plymouth one time because I did not want to pull the engine ( 6 cylinder ). Never again will I hone that much. I had a good Sunnen hone and kept track of taper. But it starts out good but when you hit base metal it takes forever. It is hard work and messy. Do yourself a favor and have it bored.
In the long run it will be a better job and faster.
Rod
 
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