Yes it has a balancer The car is a 72 duster 340 auto on the floor number matching 8.5 pistons j heads with 1.60 and 1.88 intake had a vibration at idle didnt pay much attention about it at first when i got the car. i put a little bigger cam than stock and added some u heads 1.88 with 2.02 intake valves still had a viberation at idle or should i say the motor shakes. So I had the motor rebuilt 40 over pistions with a new cam lifters same u heads when i got it back got it running still have a shake. new plugs, wires, distributor, new control module checked the wires going thru the fire wall ive had several mechanics look at it no body can figure it out even the guy that built the motor. Two diffrent carbs eldbrocks 650 new. It will smoke the tire when u get down on it but idles rugh and dies as u stop at red light. i have set the timming every where now its around 28-. I replaced the motor mount on drivers side and now im going to do both. Some friends have cams much bigger than mine and there motor idles smooth Not sure on the cam specs, ill try to find out but its less than 500 lift. Ill ask the shop that built it what crank is in it.
