I have an '85 305 z28 with a non-cc qjet. When I floor it, the secondaries open but the RPMs will not go over 3000 and I won't gain speed. It has a hard time getting up even gradual hills; I can have it floored in second gear and have a hard time exceeding 15 mph.

I have adjusted the timing and tested it at 6*, 8*, and 10* and still have the same problem. Could it be a carb problem? What could be causing this?

 

Without knowing anything else, like is it a rebuilt carb, or new, did it run alright before you installe it etc. My guess it that the secondary is way fat. Like I said just a guess without knowing more history.

 

mine does something VERY similar to this. TON of power in the first 2 gears, after that, it falls on its face and has a hard time goin past 3K RPM as well. The only conclusion I have, is I have vacuum leaks, and my carb isnt' adjusted correctly for my engine (cause I don't know much about carbs yet

Good luck

 

is the choke coming on? mine had a problem with the choke coming on a couple of years ago; as soon as i disconnected the choke it ran fine, but started a little harder