Mercruiser 5.0 2-bbl Bravo to 5.7 2 bbl Bravo

[Red955i]

In doing this swap is it necessary to change the TB IV ICM from V22 to V22A? Curves are the same till 2000rpm but 5.0 gets all advance at 3400 vs 4500 for 5.7...
Thanks

 

[alldodge]

In doing this swap is it necessary to change the TB IV ICM from V22 to V22A? Curves are the same till 2000rpm but 5.0 gets all advance at 3400 vs 4500 for 5.7...
Thanks

Saw this yesterday and thought for sure someone would comment. oh well. Agree both engines have a different advance curve and they should probably stay that way. The 5,0 has a different cam then a 5.7 which would impact the advance curve. The 5.7 has a lot more torque and it coming on to soon may cause issues. No expert but maybe now someone with more knowledge will come in.

 

[Fun Times]

Hi there, for the safety sake of your engine plus for the accuracy of information that we all do our best to give out here on iboats..... yes it would be a good idea to change over to a different ICM recommended by Mercruiser. There have been some members that have been able go without switching over ICM's so your mileage may vary.

What year are the new and old engines? (serial numbers?) Some engine models use different carburetor venturis sizes while some don't.

What size boat? The bigger and heavier the boat is, the more concern you'd have about this.

http://www.boatfix.com/merc/bullet/95/95_11.PDF

 

[NHGuy]

In 1989 the 5.0 and 5.7 used the same advance curve. It's not essential to get the V22A, but it's conservative and a later design. It will help the engine get max power with less likelihood of detonation.

I also looked up the carburetor jets and metering rods. They are so close that I'd run the carburetor as built. If it gives you trouble you can get the exact jets and rods. It won't though, they are only .001" different so it should not be noticeable.