TOPIC: 1966 merc 500 no WOT

Runs great at 30mph half throttle but bogs and wants to die if wot, assume fuel flow filter, pump, any ideas be for I rip into it, can reeds cause this?

It ain't reeds if it can get up to 30mph. Reeds would give you trouble at idle and a severe bog out of the hole.

More likely fueling issues as you mentioned, I'd take a hard look at the fuel pump if you haven't recently renewed the diaphragm; check for any trash in the pump's check valves and also check the carbs.

Pull & inspect/clean the filters atop the float chambers. Pull the float bowl covers and you can get a good look at the carb innards; if the float chambers are gunked-up badly you'll want to remove the carbs for a thorough cleaning.

Minor cleaning can be done with the carbs still bolted-up. Get a "carb packing kit" if you need any of the small gaskets, washers, or other consumables. 1 kit per carb.

Renew the floats if they are the old red or black plastic (or cream-colored foam); they are not ethanol-resistant. The new white plastic floats are alcohol-resistant.

Check needles/seats for any restrictions/trash. Check/adjust float height & drop to make sure they're in spec.

Note that other things can cause a bog at speed, one way to test for carb issues is to hit the choke (on/off real fast) and see if the motor picks up. If it wants to die, likely not overfueling. You can also have a passenger pump the primer bulb to check for fuel pump/supply issues.

Make sure the throttle linkage is advancing fully and carb butterflys are wide open at full throttle. Check the economizer collar on the magneto; if the collar is stuck, the mag won't properly advance once the carb stop is hit.

Just a few things to start with, if you find nothing obvious we can delve further.

HTH.........ed

Thanks Ed, that helps a lot
Steve