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By Deyomatic - Last Month
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I saw a classified ad yesterday for a '32 Ford with a 239 Y block that had been bored out 0.80 over. Seemed like a lot...my calculator gives me 360 cubic inches, if that's the case. Is that feasible for the 239?
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By pintoplumber - Last Month
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My ‘54 239 is bored out to standard 272 size with a 312 crank. I only have 283”. It was bored + .120 or .125
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By Joe-JDC - Last Month
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3.500" + .080 = 3.580". 3.580 x 3.580 x 3.100 x 6.2832 = 249.6368 cubic inches. bore x bore x stroke x 6.2832 = cubic inches. Joe-JDC
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By Deyomatic - 8 days ago
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Well there you go...I was about to blame the online calculator I used but turns out, I forgot how decimals worked. (Dummy). I had my "0" in the wrong place!
Good to know that they can be hopped up a little.
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By Ted - 7 days ago
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As a general rule, most Ford Y-Block engines will safely bore 0.060” over their standard bore sizes. Any more than that and it’s recommended to sonic test the cylinder walls for thickness before doing any actual boring. Core shift can be a problem and sonic testing will bring that to the forefront. Offset boring the cylinders can restore some integrity to the cylinder wall thickness where core shift is a problem.
There are a number of 272 engines out there that have been bored 0.125” over but sonic testing those after being bored, finds them marginally on the thin side for any additional boring. I have successfully bored a 272 that was cast in 1954 to 0.375” over the standard size when sonic testing showed it to have extremely thick cylinder walls. That engine is still running today after three decades of running.
An exception to that 0.060” over boring rule is a 1962 312 block that when sonic tested, had core shift so bad that the cylinders could only be cleaned up 0.010”. In another instance, there was a 100K mile 390 Ford block that was bored 0.030” over and broke thru to the water jacket on one cylinder. That effectively meant that there was less that 0.015” of wall at that point. That cylinder was sleeved without further checking and the engine ran just fine after reassembly.
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