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Old 08-18-2019, 04:04 PM
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Default '63 Tempest 326 V8 maximum overbore?

What is the max overbore on an original '63 326 TEMPEST one-year-only block?

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Old 08-19-2019, 11:19 AM
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Can it be sleeved to 4.062 ( std 389 bore)?

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Old 08-19-2019, 11:47 AM
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You would have to get it sonic checked. I don't know much about the 326's. I have several 4 bangers that are at .120 over bore.

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Old 08-19-2019, 12:39 PM
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I don’t think you want all 8 sleeves anyway

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Old 08-19-2019, 12:57 PM
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According to the 1966 Pontiac Chassis Parts Catalog, Pontiac only supplied oversize pistons for the '63 326 (actually 336) to +0.030" = 3.810". Not saying you couldn't find larger pistons elsewhere.

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Old 08-19-2019, 04:30 PM
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"You would have to get it sonic checked..."

^^^^^^^^^THIS^^^^^^^^^^^^

No matter what block you use, you must know how much meat you'll have left, after required bore/hone. Core shift & years of corrosion can reduce cylinder wall thickness on any given cylinder.

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Old 08-19-2019, 10:03 PM
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Quote:
Originally Posted by ponyakr View Post
"You would have to get it sonic checked..."

^^^^^^^^^THIS^^^^^^^^^^^^

No matter what block you use, you must know how much meat you'll have left, after required bore/hone. Core shift & years of corrosion can reduce cylinder wall thickness on any given cylinder.
I know of a 326 at .090 overbore. My 421 is .070

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