340 deck height

[B.Tallent]

does anyone know what the piston deck height is for a stock 68-70 "340" I can't find it in my book thanx

[Tarrbabe]

The MP book I have says the deck height for the 68-70 340 as +.045 above the deck.

[Mr.Mopar]

I just installed pistons made by Ertel, Cast 10.3:1, 68-71 340. The piston is .016 out of the hole and I had .005 off my block to straighten it up. They are supposed to be direct replacements for the 68-71 340. Also there was a note with the pistons saying that they are .020 shorter to compensate for milling and decking. So if you add the .020 to it they should be at .031 out of the hole. I subtracted the .005 that was milled on mine because yours is probably stock height. Sound right?

[B.Tallent]

Im not sure what the deck height is on mine {I havent torn it down yet} but according to mopar engines book assuming 64cc head volume the deck should be -.020. which puts the piston at.020 below the deck. everyone else says above the deck and my 1970 service manual doesnt list it. AAAAAAAAAAAHHHHHHH. I guess I will start teardown and mike everything and figure it out from actual measurements. f.w.w. the compression test was 60 p.s.i. per hole and the motor does not smoke or use oil and supposedly has only 10,000 miles on it

[Mr.Mopar]

So on mine it would actually only been .011 out of the hole if it didn't need decking. I was assuming the measurements as listed. I guess the only way to find out is to tear it down. My 8.5:1 340 wasn't blowing smoke either but had a leakdown rate of 60 percent or more. Still did 14.5 without nitrous and 13.2 with NOS. Not bad for a low compression beat up engine. Lets see the chevy guys do that! Now I've got at least 10.2:1 and the timing has to be re-curved and I guess its start over time. Good luck bud!