4.3 Mercruisers won’t get boat to plane

[Matt DiMauro]

A buddy of mine just had new motor replacements(4.3L mercruisers) on his 35’ Monterey. Originally had a 2 barrel and then upgraded to the 4 barrel while doing the motor replacements. After getting it all set and on the first sea trial, the boat topped it at 4400 rpms but did not get the boat to plane. Before the replacement we would run at about 4500-4800rmps Max. Any ideas on what could be causing this issue? The boat is free of unnecessary weight and clean of barnacles. Let me know what you think. Any advice helps. Thank you!

 

[Lazy Daze]

Matt, it would be best to stick with your original thread on this topic rather than starting the same thing again. There were some conversations going there and people starting to help. We were still waiting, though, for answers to some of the questions.