oval ore rektangular port? hp?

[didrik_sorlie@hotmail.com]

Hello,
I have an mercruiser engine number 74LM OF810263

MERCRUISER TB5, W/PS, TWOPCEX, WORO, GEN6 7.4L BRAVO

What is the hp and is it an oval ore rektangular port?
I need an new intake and carb, and the boat is in winter storage,, maby best to by original 7.4 efi system?
Thanks

 

[Scott Danforth]

Welcome aboard.

If your motor is a gen 6, then it is an L29 variant, 100CC chambered Vortec heads, large oval ports.

get another Gen 6 EFI intake. what happened to yours?

 

[didrik_sorlie@hotmail.com]

Its carboreted, not an efi at this time.

 

[didrik_sorlie@hotmail.com]

My intake is rusty, and its needing a new carburettor, (a bit hard to start, maby the elecktrik choke, thinking about edelbrock torquer an 750cfm, what is the hp in this engins? Cant find annything with the engine nbr exept the information in my first post.

 

[alldodge]

Replacing the carb can help, replacing the intake will probably not help other then appearance. You can go EFI but that is a big job and will cost a lot for not much more benefit. You should be in the 330hp range

 

[didrik_sorlie@hotmail.com]

Thanks. the intake locks bad. So ill need to replace. The ill order large oval port intake also. It takes som time getting it to norway.

 

[alldodge]

You could save some money if you take the manifold off, sand blast it and repaint. The new manifold may not gain you any hp. If you get a high rise intake you can increase torque just a bit, but if you go that route make sure you have clearance

 

[Scott Danforth]

what year? Gen 6 is 1996 and newer

your rust on your intake is most likely cosmetic. pull the intake, bead blast it, repaint. your out $25 for paint and gaskets

I definitely would NEVER run a torquer intake. the best marine intake for a BBC unless you own a race boat is the RPM air gap. you need to think low RPM torque and not race motor.

 

[didrik_sorlie@hotmail.com]

Thanks. Its a rinker 232 captiva. A lot of rust where the seal for the coling is. So a good leak even with new gaskets, so ill by a new. Not that expensive annyway.
How are the internals in this engins? Only cast? 4 bolt main?

 

[alldodge]

So a good leak even with new gaskets

This concerns me, if you have an intake leak, is it because of the intake of the head?
Make sure your new intake in marine rated, need to bronze water jacket ports, more so if your in salt water

Internals are solid so long as the maintenance was done. Motors die early only due to lack of regular maintenance, next to none have ever had much problem with regular maintenance.

 

[Scott Danforth]

Thanks. Its a rinker 232 captiva. A lot of rust where the seal for the coling is. So a good leak even with new gaskets, so ill by a new. Not that expensive annyway.
How are the internals in this engins? Only cast? 4 bolt main?

If it is a gen 6, cast crank, 4-Bolt mains, forged rods, cast pistons. Same stuff that out in truck motors

 

[didrik_sorlie@hotmail.com]

The leak is because the intake, on the top surface where the bronce seal is, it has been a leak there for years, thats why the corrosion, no big deal, but the engine is running verry nice, exept for the cold start problem, so i go for a new edelbrock and intake, the it locks nice also,

Anny god ideas to get more hp i this engine?
My maximum rpm is only 3900 rpm with my prop, som more hp would probably make it go a litle higher, and more hp would be avlaible.

 

[Scott Danforth]

The leak is because the intake, on the top surface where the bronce seal is, it has been a leak there for years, thats why the corrosion, no big deal, but the engine is running verry nice, exept for the cold start problem, so i go for a new edelbrock and intake, the it locks nice also,

Anny god ideas to get more hp i this engine?
My maximum rpm is only 3900 rpm with my prop, som more hp would probably make it go a litle higher, and more hp would be avlaible.

If your running in salt water, I would not recommend a standard edelbrock intake (without the bronze inserts). the intake would last less than a year as salt and aluminum do not mix

if your lugging your motor down to 3900, you have the wrong props. back off on pitch at least by 2"

if you want more power, you need to start with a fresh rebuild. new pistons, new cam, a bit of clean up on the ports in the head, different exhaust manifolds. If you were here in the states, you could probably do a rebuild for under $2k. If you go that route and rebuild your motor, I highly recommend installing a heat exchanger

 

[didrik_sorlie@hotmail.com]

I have an closed cooling system with heat excanger, so that is okay,

 

[Scott Danforth]

if your HX cooled, please post a picture of your corrosion and leak. How long has it been since you changed the antifreeze?

 

[didrik_sorlie@hotmail.com]

Old ovner runed it with to litle anti freeze, thats why the corrosion, sorry, boat is in qinter storage