310DA Engine replacement and modification

[Sprint7TW]

For some reason (yet unknowen) I lost the starboard engine under cruise power last weekend.
I was just crusing along when I heard the engine miss and sputter so I immediately shut it down. Tried to restart it and it was locked up and would not turn over. Returned to dock on the port engine and checked the oil and found the oil to be way overfull. (water) I belive that I may have dropped a value.

I have always felt that the boat was under powered. (260HP with a 2bbl).
I ordered a new create engine with the 4bbl Edelbrok 1409 carb from Michigan Motorz.
I also ordered a new manifold and the exact same carb and linkage for the port engine.
My question is, has anyone on the forum done this? If so, were there any unforseen problems with the switch? Could you tell any big change with performance? It should add about 30HP per side.
Did you need to make any prop change?
Thanks in advance for your replies.

 

[Sprint7TW]

I can't believe that nobody has not done this?

 

[Quint4]

Not what you are asking but.....I replaced an original Weber carb on a 454 with an Edelbrock 1410 and the Edelbrock was great.

 

[scoflaw]

Unless you have the vortec heads or the gen 1 heads with the 2.02 intake valves, I don't see a 30 hp increase. The better flowing heads are what makes the power.

 

[dlvwill]

Unless you have the vortec heads or the gen 1 heads with the 2.02 intake valves, I don't see a 30 hp increase. The better flowing heads are what makes the power.

+1 carb is a part of a system and all needs to work in concert. Too much carb can be a worse problem than too little on boats. (Not an issue with 1409 Edelbrock which has vacuum secondaries)
Remember you are always working below 4600 rpm and cant use all the breathing a 4bbl gives you anyway.... vortec head upgrade the biggest bang for the buck. Torque moves boats, not horsepower......

 

[SCORPIO]

I replace a 5.7 Merc with a vortek 5.7 from Michigan motorz. My port is now a 325 HP vortek and ny starboard is the stock 260 HP version. The boat runs fine and both are in sync at up to 3400 rpm, I have not done a WOT run yet and don't run my boat that hard but I suspect the new engine will out perform the stock unit as it is rated max HP at around 5500 rpm vs 4600 for the old one. I plan to someday replace the other engine with a vortek engine.

 

[Sprint7TW]

Unless you have the vortec heads or the gen 1 heads with the 2.02 intake valves, I don't see a 30 hp increase. The better flowing heads are what makes the power.

I guess that I failed to state that I do have the vortec heads.

 

[Sprint7TW]

Not what you are asking but.....I replaced an original Weber carb on a 454 with an Edelbrock 1410 and the Edelbrock was great.

Thanks for the reply.

 

[Sprint7TW]

I replace a 5.7 Merc with a vortek 5.7 from Michigan motorz. My port is now a 325 HP vortek and ny starboard is the stock 260 HP version. The boat runs fine and both are in sync at up to 3400 rpm, I have not done a WOT run yet and don't run my boat that hard but I suspect the new engine will out perform the stock unit as it is rated max HP at around 5500 rpm vs 4600 for the old one. I plan to someday replace the other engine with a vortek engine.

That surprises me that they would run in sync up to 3400 rpm.
I would have never got on plane at 3400 with the 260hp engines.