WOT 6000 rpm

[TheSouthpaw]

Hello all, I have an 1990 Monterey 189 with a Mercruiser 230 & Alpha 1 Gen 2 outdrive. It used to have a 4.3 motor in it but the motor was damaged due to poor winterization. Since the new motor has been installed my WOT is around 6000 rpm with a 23 pitch stainless prop. Everything that I have read says WOT should be no higher than 5600 rpm but also read 4400-4800 and that confused me. My question is Is this WOT to high and will it damage my motor and if so how do I lower it to normal range. Boat runs around 40 mph on the water WOT. Thank you in advance for the help

 

[Sea Rider]

Welcome to Iboats,

Firstly need to know exact wot RPM range for your engine, then can play with prop pitches all you want to best suit your boating needs.Will need to go up several pitches to lower your current wot RPM.

Happy Boating

 

[rallyart]

You can be sure that an older small block chevy will not have a redline over 5000 RPM. If it's from the '90s you will stretch a rod bolt and float the valves at 6000. You'll be able to see which when the inspection hole shows up on the side of the block.
If it's new it would probably have a rev limiter built in to the electronics.

 

[Scott Danforth]

when you went from the 6 cylinder to the 8 cylinder, did you adjust the tach correctly? there is a 4-6-8 switch on the back side.

 

[steelespike]

If the 4.3 was a 190 it probably has a 1.81 ratio the 205 4.3 uses a 1.62 as does the 5.0.
Your Motor rpm range is 4400-4800.As Scott suggested be sure the tach is set for an 8 cylinder.

 

[TheSouthpaw]

Thank you all for the reply Scott you asked about setting the tach correctly. I did not change any of the setting after the motor swap. You mentioned a 4-6-8 switch on the back side. Would this be on the back side of the tach? Sorry I am not very boat swavy yet. Steelespike yes the original 4.3 was 190 hp.

 

[steelespike]

While I have never been behind a tach I'm sure the adjustment is on the back of the tach.Probably fairly obvious.
The 1.82 will require a little more prop.
Once your set right get us a wot lightly loaded max gps speed and rpm.

 

[Scott Danforth]

Yep, back side of tach

 

[TheSouthpaw]

Thank you again for you help. I was thinking about buying a digital tachometer that you connect to you plug wire and was wondering if anyone has used one and are they accurate.. I will check the back of the tach tomorrow. Thank you all again for your all your help!!