I am rebuilding a 1970 340 for the street, not for racing. My 69 Dart has stock a AVS, intake, 2.02 heads, and stock exhaust manifolds. It is a 4 speed with a 3:55 rear end.
I’ve read that the compression ratio should be less than 10:1 to run on pump gas. I wanted to error on the safe side, so I was thinking about 9:1 to 9.5:1. Of course, in 1972, the 340 CR was reduced to 8.5:1. Maybe that is the way to go.
The block will be bored .030. Any suggestions on the appropriate pistons? Cast or hypereutectic?
The stock cam was Adv Dur- 268/276; Lift- 429/444.
Compcams recommended a step up from the stock old technology: the hydraulic Xtreme Energy cam, No. 20-222-3, which has Adv Dur-262/270; Lift- 462/470; RPM Range- 1,300-5,600. They said this would provide the best street manners.
One more step up for Compcams is No. 20-223-3, which has Adv Dur-268/280; Lift- 477/480; RPM Range- 1,600-5,800.
Does anybody have any suggestions on any of this combination?
Much obliged.
