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1967 340 4bbl rebuild no cheap pistons


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has anyone ever heard of boring a 340 out to be a 350 and using the 10.25 to 1 compression 350 pistons in the bored out 340 block?<BR>It seems most numbers fit the picture. can anyone help me?<P>The 2bbl 340 has available pistons(9:1), but the 4 bbl 340 requires a piston that does not exist anymore.<P>If you have any info that might help me I am at dan.jubenville@sympatico.ca<BR> cool.gifcool.gifsmile.gif

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I'd look hard at available fuels before completely dismissing the 9:1s. The 10.25s are going to require high octane fuel or additives to be happy and not ping holes in themselves. The 9.0s will run happily on 93 octane.<P>This is one modification I have no problem doing. It will allow the car to be used and enjoyed and gassed up almost anywhere.

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You don't want the 10.25:1 pistons in a street-driven 340.<P>I have to run a 2:1 mix using 110 octane leaded racing fuel to get mine to stop pinging.<P>And, that's after 20 years of trying everything else. <P>When I rebuild, it will be with 9:1 pistons.

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We bored out a 225 and put later pistons in it and strange as it may seem,the engine wound up with 231 cubes .It ran fine .I have a near-new 340 short-block I would sell.

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I have a 340 bored .050" with 10.5:1 forged 350 std. pistons and late model 350 rods with ARP bolts. Be careful the mach shop understands .050 not .060!

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Thanks for your input. I have decided to slide the old pistons(with standard rings) back in until they smash their way out of the side, then I will likely rebuld the 2 bbl block .050 to get a 350 out of it 10.25:1. I have found I can get away with 94 octane fuel as long as I keep her to the boards. After a year of my torchure and 2 intake lobes worn round, all my pistons and valves looked ok (ie not burnt)<P>sorry if i seem a bit unprofessional, it's because I am unprofessional.<P>once again thanks guys, I didn't think anyone ever thought about poor old buicks like my betsy anymore, but it sounds like you all have some interest....

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