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I am considering a big overbore on a 1.9 liter block(.130). Which year block would probably have the thickest cylinder walls? I have the following years to pick from
1970, 1973, 1974, 1975
 

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Old Opeler
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Bore Size

1.9L blocks - of any year - are regularly bored out to 95mm (+.080") and to Chevy size 3.75" (95.25mm) whichis +.090" without any reports of big problems. One poster reported boring out to 103mm so that sleeves could be fitted.

+.130" is starting to get "out there" on bore size as it is a full millimetre above 265 Chevy size - do you have some +.040" Chevy pistons you want to use?

The biggest problem encontered with large overbores is the thickness of the cylinder walls at rust spots in the water jacket. So choose the block you have with the least sign of rust in the water jackets and get the walls sonic tested for thickness before you start. It is possible to "move" the bores to leave the thrust side a bit thicker than the other side of the bore .......... or you could bore the block out larger and sleeve each bore to ensure that the cylinder walls were sound ..... or just get smaller pistons and save yourself some grief!
 
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