03 5.0 to 5.7 swap..ICM/ECM?

[saleen281sc]

Hey all...thanks for a great forum!

I have a 2003 Mariah with 39..yes, 39 original hours on it. It has the 5.0 Thunderbolt V ignition motor with 2v TKS carb.

The boat was winterized, and spent its only year outside in the elements. Needless to say, upon taking it out to get ready for the season..BAM..we have a cracked block.

So- I have decided to go ahead and drop a 5.7 in it (longblock) and move on.

My question is..I know the 5.0/5.7 share a ton of the same, if not all major parts..but what about the ICM (or is it ECM?)?

Does this need to be purchased so that the engine is tuned and runs correctly? Any other issues in swapping over to the 5.7?

Also, with the ultra low hours, are the heads or any other parts off the original motor worth trying to salvage and sell?

I will probably go with MichiganMotorz unless theres bad reviews out there on them I haven't been able to find, from what I can tell they seem to be pretty reputable.

Thanks in advance.

 

[Bondo]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

Does this need to be purchased so that the engine is tuned and runs correctly? Any other issues in swapping over to the 5.7?

Ayuh,... It's a Carbed motor, No worries about the electronic controls,...
Only with the EFIs...

Btw,... Ditch the 2bbl,+ drop on a 4bbl.,+ manifold...

 

[ENSIGN]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

Have your manifolds pressure tested they may also be cracked!

 

[saleen281sc]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

Ayuh,... It's a Carbed motor, No worries about the electronic controls,...
Only with the EFIs...

Btw,... Ditch the 2bbl,+ drop on a 4bbl.,+ manifold...

Ahhh..thank you. I'm an idiot!

For some reason I thought the ECM contained spark advance info or something like that.

I guess the "little black box" on my boat is just for spark knock then.

Also, I agree with your 4 barrel comment...but was told that by keeping the 2 barrel I'd get better gas mileage, but lose about 10 hp. My local boat mechanic told me the 5.0 and 5.7 intake manifolds are the same?

I think the 2v 5.7 was rated at 260 or 250? Can't remember.

Irregardless, what kind of carb could be used with that setup..another "Mercruiser" carb?

 

[saleen281sc]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

Also, can someone tell me if any of the power steering linkages, rods, etc have to be removed to take out the motor? I know the supply lines have to be removed, but reading the Merc manual (DL'ed from this site ) it didn't say that stuff needed to be removed.

 

[John_S]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

For some reason I thought the ECM contained spark advance info or something like that.

It does.

I guess the "little black box" on my boat is just for spark knock then.

Only if it has the knock sensor and knock module. I believe yours does not.

Also, I agree with your 4 barrel comment...but was told that by keeping the 2 barrel I'd get better gas mileage, but lose about 10 hp. My local boat mechanic told me the 5.0 and 5.7 intake manifolds are the same?

Check the service manual on the 2V carbs. See if they are the same. The 5.7 probably has different jets. Intake would be the same.

Milage may improve with 4brl, if you can keep out of the 2ndarys. I would say 20-30hp.

I think the 2v 5.7 was rated at 260 or 250? Can't remember.

250 w/alpha.

Irregardless, what kind of carb could be used with that setup..another "Mercruiser" carb?

Edelbrock 1409 is the forum favorite.

 

[saleen281sc]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

It does.




Only if it has the knock sensor and knock module. I believe yours does not.

Looking up the part # off my black box, it does indeed have a knock sensor.


So, again..if the ECM carries spark advance info, wouldn't I need a different one?

 

[180shabah]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

First the 5.0 and 5.7 are the same block, so all of your externals are a direct swap. Your 5.0 was rated at 220hp. A vortec 5.7 will net 250hp with 2bbl carb, while a decent intake and 4bbl will give you a solid 290-300hp.

Another vote for the edelbrock carb, and if properly tuned you won't notice the difference at the gas pump.

you will also need at the very least, a new prop, but possible my need to regear to compensate for the additional power.

 

[John_S]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

Looking up the part # off my black box, it does indeed have a knock sensor.

So, again..if the ECM carries spark advance info, wouldn't I need a different one?

I couldn't check by the year, but MercruiserParts.com indicated for a W series serial #(latest it has) the 5.0L Alpha would not have it. Merc doesn't publish the timing curves for T5. For other years, there was a different part number for 5L and 5.7L, and presumably different timing curves. They were different back on T4. Now, I wouldn't consider it significant, and "I" would go ahead and run it. You are afforded some extra protection having a knock module/sensor. Just run through the checks in the service manual before you do some wot runs. Or, if it is a different part number, and want to be safe, they go for a little over $400 a pop.

You should have two black boxes piggy-backed. One is the ICM and other is the knock module. You will need to remove the knock sensor from your 5.0 block. What is your current ICM part number?

 

[saleen281sc]

Re: 03 5.0 to 5.7 swap..ICM/ECM?

I couldn't check by the year, but MercruiserParts.com indicated for a W series serial #(latest it has) the 5.0L Alpha would not have it. Merc doesn't publish the timing curves for T5. For other years, there was a different part number for 5L and 5.7L, and presumably different timing curves. They were different back on T4. Now, I wouldn't consider it significant, and "I" would go ahead and run it. You are afforded some extra protection having a knock module/sensor. Just run through the checks in the service manual before you do some wot runs. Or, if it is a different part number, and want to be safe, they go for a little over $400 a pop.

You should have two black boxes piggy-backed. One is the ICM and other is the knock module. You will need to remove the knock sensor from your 5.0 block. What is your current ICM part number?

Not sure on the knock module.., but the one blackbox part number that is legible is 861459T1 which shows as a 5.0 Alpha ICM module. Looking thru mercruiserparts.com this number is consistent thru all production numbers.

Thats the only box I see.