Don't know if this was posted already, sorry of it was, but a little info on the 340 from Allpar.com. Not sure how accurate their info is but here it is anyways....
http://www.allpar.com/mopar/mopar340.htmlOne of the best engines of the 1960s and 1970s for performance enthusiasts was the 340 V-8. It had high-flow heads, big ports, a two-level intake manifold, and a six-barrel option (three two-barrel carbs). The package allowed for high speed with the light weight helping handling.
The 340 cars gave away nothing to the 383 cars in a straight line, and were ahead of the 383 cars on anything involving turns — and spark plug access.
When the 340 came out in late 1967, it was a street fighter from the start. Separating the 340 from the standard-performance 318 were not just 22 cubic inches, but also:
a dual timing chain with a windage tray to improve top end engine RPM by keeping the crank counter weights from 'churning the oil' in the pan.
2.02 inch intake valves and 1.60 inch exhaust valves
a high-rise dual plane intake
an 850 cfm carburetor (from 1971 to 1973)
a forged steel crank (through 1972’s engine #39118000, when a cast iron crank was used)
high-performance heads
a revised oil pump with a 90 degree adaptor
a special carburetor and cam
The 340’s best power rating was 290 horsepower; even in 1973, it still managed 240-245 net horsepower.
A good-running, early 340 in a lightweight A-body or Road Runner embarassed many big block engines. Though relatively few were made, many parts interchange with 318s and 360s.
