popping back through carb

[lee armistead]

facts: 302 V-8 ford backed by Jacuzzi 12YJ jet newly installed in a Wellcraft Air-Slot 21 tri-hull, 2 Bl motorcraft carb. Newly installed Prestolite electronic distributor. Has a coil presently installed that requires a separate resistor.
Problem: engine perfectly tuned at 10 degrees advanced past TDC at 800 RPM as it sets in the shop. Put the boat in the water, naturally jet pump loads the engine. Rev engine to 2200 RPM and it pops back through the carb? Engine will not develop more RPM's.
Thinking: Engine with no load runs good so fuel and spark are fine, load the engine, fuel continues to be distributed to the cylinders in the normal fashion. In accellerated condition (above 2000 RPM) the new dizzy with its built in spark advance is not delivering enough spark to the plugs to burn the gas being delivered to the cylinders? When it does fire, it pops back through the carb? To much fuel?
Solution: Install a high voltage coil that the voltage output is not reduced because of the resistor requirement? Should the resistor be removed prior to the install of a new UC16T coil?
If there is anyone out there that really knows engines and can follow my thought process to resolve this issue please give me your input. My direct email address is leearmistead1@netzero.net and my phone # is 813.294.1481. Help me out if you can

[lee armistead]

Originally Posted by lee armistead

facts: 302 V-8 ford backed by Jacuzzi 12YJ jet newly installed in a Wellcraft Air-Slot 21 tri-hull, 2 Bl motorcraft carb. Newly installed Prestolite electronic distributor. Has a coil presently installed that requires a separate resistor.
Problem: engine perfectly tuned at 10 degrees advanced past TDC at 800 RPM as it sets in the shop. Put the boat in the water, naturally jet pump loads the engine. Rev engine to 2200 RPM and it pops back through the carb? Engine will not develop more RPM's.
Thinking: Engine with no load runs good so fuel and spark are fine, load the engine, fuel continues to be distributed to the cylinders in the normal fashion. In accellerated condition (above 2000 RPM) the new dizzy with its built in spark advance is not delivering enough spark to the plugs to burn the gas being delivered to the cylinders? When it does fire, it pops back through the carb? To much fuel?
Solution: Install a high voltage coil that the voltage output is not reduced because of the resistor requirement? Should the resistor be removed prior to the install of a new UC16T coil?
If there is anyone out there that really knows engines and can follow my thought process to resolve this issue please give me your input. My direct email address is leearmistead1@netzero.net and my phone # is 813.294.1481. Help me out if you can

Update 09.19.06, as it would appear out of 21 views of this posting there has not been, not one person that could help with this problem. I'm glad I wasn't holding my breath for a good response. Just to let anyone who might be interested this problem has been solved.

Solution: I went ahead and installed the UC16T high voltage coil, that wasn't the problem though. Let me remind everyone that the engine is a Ford V-8, 302 CID.

As I have learned, most marine engines are an after market product. Having said that, it is very important to know as much about the engine specifications as possible.

Somewhere along the life of my engine someone install a new camshaft. I reset my timing order to that of a Ford 351W instead of the factory 302 recommendations.

Cured everything.

Lee Armistead, leearmistead1@netzero.net

[drewpster]

Did you mean firing order? Or ignition timing?

[longliner45]

sound like a problem I had ,, get this ,a crack in the head at the valve seat under the valves and hard to detect,,,same symtomes ,,let us know longliner; do a compression check

[lee armistead]

Sorry, I meant the firing order.

[lee armistead]

Did a compression check. All cylinders ran between 125 and 130 lbs. New plugs, new spark plug wires. Engine starts and runs fine now since I changed the firing order. I have another problem now! Overheating!! If I run up to and hold RPM's over 3100 the engine starts to overheat. I'll be pulling off and checking all of the on-board cooling system components. Its a closed system except for the water pick up from the jet that circulates through the exhaust manifold. Past use has only been in fresh water?