I have a 340 that has been bored 40 over and is about 2 over the 40. To clean the wall's I'll have about 43 over total. What piston's would be good with that amount of clearance. I was thinking maybe KB's Need lots of opinions.The other question is that the lifter bores have bronze bushings in so can I use normal hydralic lifters.

Thanks Moparts

Sounds like it time for sleeves or another block to me.

have it sonic checked first

Sounds like pretty spooky territory to me, especially if you plan on making some power with it. Definitely sonic-test the thing and hope for at least .200 on the walls. Pistons & rings might be tough or expensive to find for 4.08-ish.

200 would be awesome but already at .040 over I'll doubt you'll see that. For a street build I'd feel ok with around 150 thick on the thrust sides. You might get a surprise on the sonic check, I have 2 examples of STANDARD bore 340 blocks that only had .080 thick walls on 1 thrust side bore, the other 7 were normal and around 200!

yep need to have it sonic checked I have seen a few that where ok at a .060 overbore.

As said sonic check it & .043" over doesn't sound too bad & it might be OK going 60 over if you have to (did I say sonic check) or might have to go w some forged pistons if you stay w 40 over (as you know the less over the better). Some pistons their spec has the clearance built in but you know your actual bore size that it will clean up to (including honing I am assuming) so find a piston that will work w that.

I'm not looking to make tons of horse power. It is the original block and I just want to cam it up alittle over stock and use J heads. Just don't know if I can find pistons to use and if the lifter bores with the bronze bushings can use hydralic lifters.

If it were mine and it was already at .040 over, I'd sleeve all 8 back to standard and move on,,,,just my

Finding decent pistons at 60 over will be tough if not impossible. If it's a numbers block, sleeve it. $80/sleeve is the going rate.

The lifter bushings were probably installed for a hydraulic roller cam. The condition illustrated here shows why:
http://www.hughesengines.com/Index/produ...mp;partid=25802

Should be okay for use with a flat tappet. Someone spent a lot of money on that block.

I hear you Bill but along those lines, it's a $800 job to sleeve all 8.

I'd be more prone to find another block (regardless of how it sonics) and build a different engine, or even a 360 (cheaper on average and looks identical) then bag and tag the numbers matching block and stash it for safe keeping.

Boy I'm glad I found this thread. I just pulled the original 340 out of my Challenger today to take a peek inside. It was supposedly rebuilt in 2006 when the car was restored but I was having some issues with it. Anyhow, I found the 340 bored .040 over like 72 RR Dude and came here to find out what the max bore size that's safe. Thanks to this thread, I know what I need to do.

Besides being .040 over, the cylinder walls are scarred and the crank is .010/.010 and scarred as well. I don't think they did a very good job on the rebuild. What a shame. I think I'll probably have the block and heads checked and verify they're not cracked etc and store the engine away for future use and just buy a crate motor. Hmmm... which one to get...