1975 rochester 2gc carburetor

"Hello, I have been having pro

"Hello, I have been having problems with a 1975 mercruiser 233hp boat. Low idle would vary from 600 to 950 when cold and warm. Had top end of rpm of 3100 at a operating temp of 180. Could not get a smooth idle, so change plugs, wires cap, and rotor. Replaced filter in the rochester 2gc carb and cleaned with carb cleaner. Adjusted idle mixture screw, only one because I could not get the other one to turn at all, acheived vacume reading of 14 to 16. Got motor to idle fine, and took out for test and does not have enough power at top end. From what I can tell this is the original carb. Any way to adjust better for top end? Wanting to back fire also. Also vacume reading would drop to less than 6 after trying to power up. Another problem is that I have never been able to get the manufactures specs of wot 3800-4200 rpm. Just up to 3100 rpm with a 16X11p prop. Direct result to carb for a while? Any one have ideas or adjustments? Think I should have the carb rebuilt? Please help Thanks"

"The lowered vacuum at power i

"The lowered vacuum at power is normal, the changing idle speed is not (unless the throttle linkge is not 'settling down' in the same place as you idle down--I've seen that before. Be sure the throttle stop on the carb is detemining the idle position, not the throttle cable.)
On the lack of top end, lots of things can cause that. You may be blaming that poor carb for a tweaked prop, dirty bottom, water in a double bottom, bad gas, etc.

Jeff"

"put a new prop on fridaybefor

"put a new prop on fridaybefore this problem,after adjusting idle mixture screw, would idle good, very poor running above 2000rpm, could timing be off? dwell setting on points make it run bad under power? or bad carb? If I check and adjust the timing, will this maybe correct this? any help would be nice. good gas, put new water seperator filter on,dry gas in tank new plugs , fiberglass hull ,,thanks Tim"