340 Mopar Engine build Episode 3: "Collecting parts and gathering thoughts..." 

Chrysler used 3 different j heads . In 1970 they were all 2.02 intake . Also the T A six pack head 2.02 .In 1971 early still had 2.02 late going into 1972 were 1.88 intake . All were j heads . Note In 1968 and 1969 there were X heads casting # 894 also stamped 340 also 2.02 . Note 1970 and newer j heads had a 360 cast # on the head. All the 2.02 castings flow the same 1.88 castings same flow ports just smaller intake valves . Hope I helped . Great video

68 and 69 pistons. 70 pistons had 4 valve reliefs.

Although it's over a year old video it was a good one!you can tell this guy has put a lot of upfront thought into this project.. good-looking parts. those Pistons are in excellent condition and that's my question of the day what did those Pistons come out of???

1972 and 1973 were the low compression 8:5 to1 1968 to 1971 had 10:5 to 1 . 8.5 had 4 notched top 10.5 had 2 notch top of piston all were floating wrist pin .

J heads are for a 71 340 only. They'd be 2.o2 1.60 valves. Those heads are just 360 heads.

I'm 69 years old. My first new car was a 71 Demon 340. It had the 360 J heads with 2.02 intake. My brother had a 70 Dart Swinger 340. It had the 360 J heads too. His engine actually had 4 larger connecting rods like my 71 engine. His other 4 rods were early 340 rods like our other friend's 69 Dart Swinger 340. Most people aren't aware there were two types of 340 rods. Early and late. His engine was balanced properly as we had it checked. The early rods had more metal on each end but the beams were thinner. The later rods should be stronger for racing. Stock engines it doesn't matter. I've seen lots of crazy stuff over the years as I still have a 71 Demon with 14,200 original miles. It's a 4 speed car. Good luck on your project.

Thank you for watching sir. I do seem to think 1970 had the J heads and mixed parts like you say,It vague or I don't really know when the low comp 340s came out. I seem to think late 71 for some reason. I was 2 in 71 LOL I always appreciate info from those that were there buying these cars new.

i would have sent the pistons away for heat treatment = they are pitted badly = junk builder and that cam is needing refinishing = i would never let you near my 318 diamond build !

So you said you have 2.02 X heads but want to run the J heads? Why??