Rethinking Prop Size after Rebuild

[tysdad2010]

Hi, I am in the process of getting my 1985 Mercury Blackmax 150 Rebuilt...For some reason a piston melted in one of the cyclinders...We have looked and looked and looked and have yet to see to find out why it blew up...So we are thinking I have been Lugging the motor with this 23P 3 Blade prop I am running right now...So I am thinking about running a smaller pitch prop...What do yall think? 21p? 20p? 19p?

I have a 1986 Ranger 18ft bassboat it is heavy! Before engine blew I had really good hole shot with just me in the boat but with someone else it kinda struggled but when got on plane it was fine...The fastest I ever had the boat was 49MPH at WOT with just me in it....

Also We have checked the carbs are a really looking clean but we have yet to check the jets to see if maybe one of them might be clogged or something ...that might have caused it is melt the piston in the cyclinder...

 

[Bondo]

Re: Rethinking Prop Size after Rebuild

Hi, I am in the process of getting my 1985 Mercury Blackmax 150 Rebuilt...For some reason a piston melted in one of the cyclinders...We have looked and looked and looked and have yet to see to find out why it blew up...So we are thinking I have been Lugging the motor with this 23P 3 Blade prop I am running right now...So I am thinking about running a smaller pitch prop...What do yall think? 21p? 20p? 19p?

I have a 1986 Ranger 18ft bassboat it is heavy! Before engine blew I had really good hole shot with just me in the boat but with someone else it kinda struggled but when got on plane it was fine...The fastest I ever had the boat was 49MPH at WOT with just me in it....

Also We have checked the carbs are a really looking clean but we have yet to check the jets to see if maybe one of them might be clogged or something ...that might have caused it is melt the piston in the cyclinder...

Ayuh,.... The fuel system is Suspect, from the tank vent, to the carb, includin' both....
Goin' Lean is the #1 cause of the melt-down...

What was it turnin' for rpms, at Wot,..??

 

[tysdad2010]

Re: Rethinking Prop Size after Rebuild

Ayuh,.... The fuel system is Suspect, from the tank vent, to the carb, includin' both....
Goin' Lean is the #1 cause of the melt-down...

What was it turnin' for rpms, at Wot,..??

5650....I was told I should be running 6k all day long....thats kind of why i wondering If i should drop down my pitch...I dont want to go slower on top end I want to gain top end but I dont want to lose the hole shot either

 

[tysdad2010]

Re: Rethinking Prop Size after Rebuild

Oh ya it is also Stainless

 

[Maclin]

Re: Rethinking Prop Size after Rebuild

Holeshot would be better, and I bet top end would be about the same if your engine can then rev to 6000.

 

[Maclin]

Re: Rethinking Prop Size after Rebuild

I was referring to going from a 23 to a 21 pitch.