1988 Cobra 50 GM wonbt turn up

"I recently posted my problem

"I recently posted my problem with "missing under load" for my 1988 cobra with 500 hours and 9 years non-use in questionable storage. Thanks for the response...the gas is fine, I have done all the right gas things. I have replaced all of the ignition tune up parts (cap, rotor, points, condens, plug wires), except the plugs. The plugs appear new, but I am getting mixed appearance from the two engine banks. Some plugs show heavy carbon and some plugs show a clean (as new) burn.

Now the engine runs flawlessly on the hose in the driveway and in the water in neutral (600 to 3500 RPM = no problem).

. Once in the water and shifted into forward gear it does not miss or hesitate, but at about 2200 RPM (12-15 knots) there is a flat spot and it will give no more
I have perhaps complicated this puzzle by attempting to make some engine changes at the same time that I am attempting to revive this very sound boat. The following may be significant:

I have changed the factory omc cooling system to a true fresh water cooled arrangement. This required changing the thermostat from 180(?) to 160 degrees.

I have installed an aft station for steering, shift and engine throttle - although I have intentionally kept this system disconnected until I resolve my problematic issues described above.

I have removed and rebuilt the factory carb -
Rochester 4bbl - note: I have done this more than once before, so I think my work is ok.

I cannot think of a reason for this engine to not turn up under load. Please send me your ideas!"

"The carbonned plugs are misfi

"The carbonned plugs are misfiring. You will not feel a misfire when engine is in neutral or not under a load. Recheck the point gap. If good then put in another new condenser. Condensers are notorious for being bad, brand new, right out of the box."

""The plugs appear new, bu

""The plugs appear new, but I am getting mixed appearance from the two engine banks. Some plugs show heavy carbon and some plugs show a clean (as new) burn. "


If all the plugs on one side are fouling out I would check the carb again. That should be a dual plane intake manifold where one side of the carb feeds one side of the motor and visa versa. If you can, try to eliminate that possibility by verifying which plugs are bad and if they are all fed by the same venturis of the carb.

Jack"

"Thanks Jack for your thoughts

"Thanks Jack for your thoughts, I have eliminated all fuel related issues. My problem seems to be ignition related. After correcting several "minor" tune-up and maintenance issues I will give her a whirl again tomorrow. I will let you know how it goes."