Merc 260 - Carb and Manifold Upgrade

[soaked]

1979 Mercruiser 260 with aftermaket closed cooling system, on a GM 350 which sits in a Carver 23' runabout... Live in SE Alaska, and use the boat for fishing and float-camping on saltwater.

Planning to pull motor and outdrive this winter and freshen it all up, clean out the bilge, do some electrical clean-up, etc...

My existing carb and manifold are well-used stock models (Q-jet carb with manaul choke and cast-iron low-rise mani). I'd like to replace them with something more modern and less rusty. Was thinking about Edlebrock carb and mani-set, nothing too agreesive - just newer. I then read several posts about not using aluminum motor parts if running on saltwater. Why?

I assume the advice is for corrosion / electrolysis reasons, but wondered if the closed cooling system and good zincs would prevent such trouble? Or maybe, I am just clueless and missing something really important.

FYI - I live on an island with very limited access to a full service marine mechanic / shop... so am willing to buy new parts as opposed to bead-blasting / hot tanking and/or rebuilding a Rochester carb (tried that once - not fun).

 

[Bondo]

Re: Merc 260 - Carb and Manifold Upgrade

Ayuh,... The Edlebrock carb is a clone of the same carb Merc. updated to after the Rochesters...
Good Choice in My book,...

The Aluminum manifold will probably hold up Ok because of the freshwater cooling...

If you're goin' through all that work,...
Grab a set of Vortec heads,+ Those alone will give you an Honest 20hp,.. Maybe 30hp...

 

[soaked]

Re: Merc 260 - Carb and Manifold Upgrade

Glad to hear some feedback, thanks you two.

Hey Bond-o, the new heads and additional horses has not escaped my consideration, right along with a new electronic distributor... BUT, how many new horses can a feller add without stressing the outdrive?

I am using an SE 106, and have been pretty happy with the unit. But I assume they're built for a certain power range. If I go adding another 30 hp to the motor, is that a problem?

 

[Bondo]

Re: Merc 260 - Carb and Manifold Upgrade

Ayuh,... Your 79 260hp up graded with Vortec heads,+ a used T-Bolt IV igntion system will live a Long,+ prosperous life along with the SEI drive...

If you're over-boring,+ replacing the pistons,... Shoot for 9.5:1 compression,+ .040 Quench....

 

[soaked]

Re: Merc 260 - Carb and Manifold Upgrade

Yep, the 106 replaces the Alpha One...

Thank you gentlemen. Should be some happy wrench time this winter, and better running next year... Thanks for the tip on the T-bolt IV Bond-o

 

[Arrow21pilot]

Re: Merc 260 - Carb and Manifold Upgrade

I have an '87 Wellcraft and I upgraded to '98 Vortec heads, Edelbrock 2116 Performer Intake with an Edelbrock 1409 Marine Carb. I'll have her dyno'd soon, but I am expecting an 80+ HP increase. Merc says the Alpha one is rated for 300 horses, but some of the original Alpha's had a big block running up to 335 HP. THe Torque is what would kill the drive, so if you don't ski and blast out of the water, you'll be just fine. BTW, mine will be putting out north of 325 when I'm done. I also added a new electronic distributor and got rid of the Merc Thunderbolt system.