I have a 1972 dodge dart with a 383, the problem is the car runs strong until I hit about 70mph at about 3000rpms. The car wont go and faster then 70mph and starts to sputter down. Does anyone know what this problem could be?

 

Check fuel flow, maybe put a new fuel filter in... Check the throttle cable for full travel

 

Could be fuel or a week coil. Also bad condenser if you are still running points.

 

Will the engine free rev above 3000 in neutral
Possibly valve float if springs are old.

 

Welcome to the Captain. All good stuff, some 4 barrel carbs have a secondary "lockout" tied in with the choke mechanism. Easy to check then I'd be looking at fuel starvation. Pulling your plugs and checking the colour might give you your answer too.

 

If you got the original gas tank, its damn sure the filter! Get a clear one so you can see when it gets clogged! Gas is clear, not brown! :-)

 

Thanks guys I ended up replacing the gas tank and fuel filter along with running a new gas line.