I have a 87 454 alpha one combo..a total of 400 hours very well taken of boat. It has not seen a lot of use in the past 5yrs the guy just lost intrest. Im about to refresh the old girl so being it has the orignal carb ive been thinking a new carb or a rebuild??? It seems to run fine but very sluggish...read very slow rpm build up...but i cannot see how a carb that old would still meter right..it's really bad on econ..Would one just pop on a new eldobrok and maybe a new manifold or just rebuild the old. I guess im a bit sketical of the old ing system while im here T-bolt 4.Iam not going to mod this motor to many limitation's i just want to run trouible free.

Just rebuild the carb, and give it a fresh tune up. Leave manifold alone. Thunderbolt IV is a good ignition system. I'd leave that alone too.

Make sure that boat is propped right . If it is not that would be a big cause of its inefficiency . Just a thought .

The prop you likely want is the Mercury Mirage 3 blade. This prop wasn't introduced until 1988. I would not do anything to the carb at this point. Make sure the bottom is VERY clean and call Brett Anderson, BBlades 920 295 4435 and he can either fix your prop or confirm the right prop for your boat. Brett can also give you the target top MPH range.

Thank you for the input. While a rebuild would be the most prudent Auto Zone had a 15% off carb deal so 349.00 and a new 750 eldo marine carb it is.