I'm looking into trading my stoker 360 short block for a 68 340 and cash.. My idea is to just get the 340 overhauled as it just blows a little smoke.

my J heads have been cut either .020 or .025 and they have an intake to match them

I understand the 68 340 was 10:1 Compression.

With my current situation with the stroker, the engine builder got the compression way to high and I think it's undrivable unless you want to run turbo blue in it all the time. It was supposed to be a 10:1 motor, It's around 12ish something.

Well I'm going to a shop I used before and did a good job for the next one. I was wondering with that cut on the heads and a stock piston, would I be getting into that same territory?

Or is a dished 9:1 piston offered for a 340 of that year?

I'm prepared to be scholed if need be, I've not had a 340 before, only 318's and 360's/stroker

'68, '69 (& maybe '70-71) 340's were factory rated at 10.5:1 compression. They were the only factory SB with pistons ABOVE deck (not sure about HP 273's). The factory listed compression ratio may have been a little bit high, but with shaved heads on an early 340, you will still be in the 10.5- 11:1 compression range. You can install thick head gaskets (commetic?) to help lower the compression ratio.

'72-'73 340's used a lower compression piston with 4 eyebrows cut in them instead of the earlier 2.

FWIW, my 10.5:1 '69 340 runs just fine on 93 octane pump gas... and as I said, the factory compression ratings may have been a touch on the high side.

Yeah after i posted i remembered sometimes the CR would be rated a little high. I'm going to think about that 340, I figure worse case I can have the stock heads on it rebuilt or get a dished piston in. I never had anything hig compression until I got this stroker and honestly with the gas the way it is these days (quality and price) I'm not real thrilled about it.