5.7 Vortec 2BBL to 350 Mag MPI Conversion

[Swill008]

Hey Guys,

I Currently have a 5.7 Mercruiser Vortec 2BBL MERCARB 250 and am putting together a MPI conversion. I Have the Engine Wire Harness (ECU and IGN) from a 350 Mag 5.7 300HP (Vortec) and Intake with all the sensors. My question is besides a new fuel pump what else would I need?

My ENG SN: 0L091309
Thunderbolt V

Donor ENG SN: 0M013927

Things I know I need:

Fuel Injection hose to Intake Fuel Pressure Regulator
new high pressure fuel pump

More money!
Better job and perhaps a bigger boat! :laugh:

Thanks!~

 

[Fun Times]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

My ENG SN: 0L691309
Thunderbolt V

Hi there, serial number 0L691309 is coming up as an MERCRUISER 7.4L BRAVO MPI L29 (GEN VI) Model No: 4542067N1

Sure you have the right number there?

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Hi there, serial number 0L691309 is coming up as an MERCRUISER 7.4L BRAVO MPI L29 (GEN VI) Model No: 4542067N1

Sure you have the right number there?

Sorry! Yes sir, she is right now!

Corrected First Post and this is the Correction as well:

My ENG SN: 0L091309
Thunderbolt V

 

[Fun Times]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Here's your new parts list for the 350 HORIZON BRAVO ENGINE ONLY MPI,
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809488+99

And your old parts list for the 5.7L ALPHA,
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=816596+98

One thing I see so far will be, you will need to figure out what wiring harness (part number?) you have to see if it will easily fit to the style/location? of alternator you have as both engines offer both brands.

http://www.mercruiserparts.com/Show...nbr=4848&bnbr=40&bdesc=Wiring+Harness(Engine)

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Here's your new parts list for the 350 HORIZON BRAVO ENGINE ONLY MPI,
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809488+99

And your old parts list for the 5.7L ALPHA,
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=816596+98

One thing I see so far will be, you will need to figure out what wiring harness (part number?) you have to see if it will easily fit to the style/location? of alternator you have as both engines offer both brands.

http://www.mercruiserparts.com/Show...nbr=4848&bnbr=40&bdesc=Wiring+Harness(Engine)

Fun Times,

Thanks! I have currently the three wire system.

The new system I just purchased looks like this:



Looks the same style, Lower Right

 

[Fun Times]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Kind of hard to tell from the photo. The two wires next to the orange wire, are they butt connectors something similar looking to these male and female wire connectors,
Shop IDEAL 12-Count Disconnects Wire Connectors at Lowes.com

Or a plug style that you would find on a sensor.

 

[NHGuy]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Do you have the donor boat? You will come upon needs for brackets and things. The fuel pump and it's related stuff will be needed, you might need a bigger alternator, and the distributor is definitely different. I just went to the Mercury Parts Catalog, and put in the 2 serial #s; one each in it's own window. Your original # goes right to a complete app, but the donor # only goes to a page that calls it a 350 MAG MPI for a Bravo.
I think you ought to print out the wiring, ignition, fuel delivery, and fuel injection pages for the original boat and the Bravo 350 MAG MPI donor to compare what's different.
The good news is when you punch down the to the parts list it bunches the Alpha MAG MPI and the Bravo MAG MPI together. Same ECM, phew! I'd get the pages, see what the Alpha MAG MPI uses and compare it to what the original boat had. I looked up the knock sensors, they are the same. So that's one thing you don't need.
I'd check block and head codes, both are 5.7 liter roller cam motors. If the heads and blocks are same it might go really well.
Good luck, it sounds like you are off to a good start.

I am looking into doing a cam, lifters and valve springs change this winter. Maybe I will be able to keep up with you!

We need a report on how it goes, so keep us up to date on your progress! And definitely tell us what you get for performance improvements.

What kind of boat will this powerplant be pushing?

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

I'm currently trying to install a closed cooling system on this engine. I've been looking for pictures of the bracketing system but I've found so many variations that I'm frustrated. If I order everything for the Accessories (alternator and power-steering) in the parts list stated above (closed cooling) will that get me where I need to be? My original engine was not closed cooled.

It seems to be that the large flat bracket is the same. I've read that the system was redesigned in 2004 because of misalignment issues (causing squealing - alternator flex). So would want the newest bracket design. (Not stating as a FACT because it's something I have read - don't have the experience to say either way) read had same part numbers just redesigned.

The engine will be going into a 210 searay sundeck NHGuy, also I have the engine just about finished. Mpi setup and the distributor is the same for my setup. I also have installed the cool fuel module, having a bit of trouble for the fuel lines to the filter assy is different. I'll probably need another/different bracket for that as well.

Btw, I have a Mando Alternator setup.

And all I have left to mount is the alternator and power steering assy. I have all brackets for the heat exchanger setup (hoses, thermostat assy, ect) partial system.

Sorry for such a late update holidays and such. My wife is a bit happier, I've been spending my time in the garage! LOL

 

[NHGuy]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Hi, Hey if you are using a previous open cooling motor and changing to closed, that's a no go. The previous corrosion in your existing motor will come loose and clog up your closed cooling heat exchanger passages.
Only add closed cooling to a new block or one from a previous closed system. Sorry.

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Sorry forgot to mention this is a new long block I'm installing and building up. (Small details! Lol )

 

[NHGuy]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Then absolutely.

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Ok, have the conversion completed (ENG wise at least).

Long version:

Put a 1999 350 Horizion MAG 300HP MPI and 4inch heat exchanger half closed cooling system on my recently purchased LongBlock. ( thinking of a full system - pretty sure the alpha 1 Gen two won't handle it however). All stock mercruiser parts.

EDIT: I have a scan mate tool not a scanner, going to buy one and I have a MEFI 3 ECM.

I used the same thunderbolt distributor (Merc) and coil. Mando alternator, and had to purchase the idler bracket and pulley along with a new belt and new power steering pulley (5.25in). Used the V6 style routing (no sea water pump - other belts too long), I also made custom steel fuel pickup lines 3/8 double flared from the filter assy to the cool fuel module - couldn't see paying 130ish per line, look great and work well, it's going to be difficult to remove a pressure regulator or fuel pump assy if they go out! I also replaced my power steering pump with an automotive I just reused my res and pressure regulator. (Autozone - can't remember part number - I'll find and post if anyone wants to know)

I'll post pics if anyone's interested in them. This boat will only be Fresh Water!

Which brings me to the question of: should I install a crank mounted water pump with a through transom pick up, tee'd off to the alpha drive with the alpha drive impeller removed? Or do you guys think the half system should be ok for now? I Don't want overheating problems.

Still have to install the engine to ensure the throttle and shifting brackets will work. (Anyone know anything otherwise if ill have problems?) I'm installing a 12MM oil draining tube with the ability to pull through the transom drain plug. I want to install a remote oil filter assy but I'm starting to run through my budget for this engine.

I have 3 complete 350 MPI injection systems - could not pass on a great deal! Hey, it came with 2 closed cooling heat exchangers as well!

And now another question, now that everything is running nicely with my eng (on stand at least), I want to have my fuel injectors ultrasonically cleaned, any suggestions? I've seen everything from 12 - 50 bucks a piece.


Short version:

Alpha 1 Gen 2 out drive, can it handle the cooling requirements for a half closed cooling system without a sea water pickup?

Also the book states fuel pressure should be 30psi, I'm getting 25 with the two second ECM pulse. But running I'm getting around 43psi. That sound ok?

I am Requesting a recommendation for cleaning injectors. ( that's easier to read!)

Should I start a new thread on some Gelcoat cracking issues and recommendations for supplies or just post on this thread?

Thanks for the help guys!

 

[Scott Danforth]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

your right on the water pump in the alpha not handling more than the half system. you can bypass, put a crank driven pump and go from there. However with only a half system you are right within specs the heat exhanger was designed for. 20psi and 18gpm of raw water.

43 psi is right on (3 bar)

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Thanks Scott! After all the reading I've been doing lately, that's what I was thinking!

Anyone have a recommendation on where to have injectors cleaned? Or have a previous experience to share?

 

[thumpar]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Maybe I missed it but if you have a donor harness that is from a Bravo going on an Alpha you will have to figure out something for the shift interrupt.

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

Thumpar, hmm didn't think of that since I first got the wiring harness. Totally forgot about It.

Any suggested way of accomplishing it? Install a relay to remove power from ignition? Or from distributor signal reference. Not sure what would be best.

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion



This is the shift wiring from my harness. It has a loop installed. Could this possibly be used in some way?

If I'm looking at the diagram correctly J2-9 should be this shift interrupt. If I got lucky and just need to plug it into my existing alpha shift plate. Couldn't be that easy could it?

These wires are purple and the other is black.



Here's my EFI side wiring harness diagram.

MEFI 3 diagrams

 

[Swill008]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

I'm currently using an S5 oil filter on my engine. I would like to get an remote oil filter kit (automotive and fabricate bracket) or marine. The question I have is what size do I need? ( oil bypass assembly change? Or use what I have?)

When I'm done it will probably be installed on the port manifold with the filter NOT upside down.

I'm a bit confused on the differences. Any help would be much appreciated. Thanks!

 

[Fun Times]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

If I'm looking at the diagram correctly J2-9 should be this shift interrupt. If I got lucky and just need to plug it into my existing alpha shift plate. Couldn't be that easy could it?

Yep, it should be that easy.

I'm currently using an S5 oil filter on my engine. I would like to get an remote oil filter kit (automotive and fabricate bracket) or marine. The question I have is what size do I need? ( oil bypass assembly change? Or use what I have?) When I'm done it will probably be installed on the port manifold with the filter NOT upside down.

Should be good with the oil bypass valve you are currently using.

Some options,
Mercruiser Remote Oil Filter Kits

 

[Scott Danforth]

Re: 5.7 Vortec 2BBL to 350 Mag MPI Conversion

here are choices on remote filters http://www.summitracing.com/search/...SortOrder=Ascending&keyword=remote oil filter

the motor doesnt know a "marine" remote filter from an "automotive" remote filter from a "industrial motor" remote filter