Guest Posted April 25, 2002 Share Posted April 25, 2002 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> Link to comment Share on other sites More sharing options...
rocketraider Posted April 25, 2002 Share Posted April 25, 2002 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. Link to comment Share on other sites More sharing options...
YellowLark Posted April 25, 2002 Share Posted April 25, 2002 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. Link to comment Share on other sites More sharing options...
Guest Posted April 26, 2002 Share Posted April 26, 2002 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. Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2002 Share Posted April 28, 2002 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! Link to comment Share on other sites More sharing options...
Guest Posted April 30, 2002 Share Posted April 30, 2002 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.... Link to comment Share on other sites More sharing options...
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