Struggling with 17059280 or ?

[GordG]

Hello All,
New boater here..and I  enjoy learning and struggling with the challenges to get things right.

The boat I have has a 260 350 5.7 "1988" I believe.
It's been misfiring somewhat as I close in on 3000 rpm.  Never had it above that... I've worked on narrowing down the causes.  Focusing on the Carb I see its a 17059280.. from a 300 mr/trs or a 454 motor.  Older style with no leak tube.  From my research the carb should be a 17080562 or -561 on this motor.  My question is if someone in the past changed out the original with the ..280 would the metering rods or jets set for the bigger motor affect my performance on my 350?  Is it worth getting the ...280 rebuilt or should I try and source the original stock carbs?  Also I see the difference between the 561 and 562 refer to Automatic or Manual transmission.. Would that have an affect on installation?  I don't have a thunderbird ignition.. currently MSD pro billet.  Thanks for any help.

[Cliff Ruggles]

Those are Queadrajet Marine carburetors so the last number being odd or even have nothing to do with the type of transmission.  I would suggest that you completely and correctly rebuild the carburetor that isn't up to par with one of my Marine rebuild kits.  If the problem is internal and most likely is it will get the carb working correctly and up to par.  The most likely problem is that at some point in it's life it was "rebuilt" and they just used on over the counter kit which will NOT have had the correct Marine high flow N/S assembly in it.  When this happens the carb works OK until you put a lot of load or RPM's on the engine then it sucks the bowl low or empty.......https://cliffshighperformance.com/product/quadrajet-marine-rebuild-kit

[GordG]

Thanks Cliff,
Thats good to know.. I will give it a shot and try and rebuild it.