Dose anyone know what the standard prop pitch is on an 1986 OMC outdrive?

[Mrgeon1]

I have a 1986 Sunbird boat that has the 3.0L OMC engine and outdrive. I am wondering that the standard pitch was for this Model? The Prop on it looks like it is too small for the boat. I didn't take the prop off to see what it has on it now. I'm just curious what the standard should be. This is the 208 cc model made by Sunbird.I have not had the boat on the water yet to see how the current one performs. Can anyone help me out?

 

[jimmbo]

Welcome to iboats
There is no such thing as a Standard Pitch Prop. Each installation is a custom match to the boat/engine/load/intended usage. Without any more info as to current prop, WOT RPM, boat it is on, and intended use, no recommendation can be made

 

[Silvertip]

Post your question in the PROP forum -- but you will get the same response until you provide some RPM and speed numbers. One size does not work for all applications.

 

[southkogs]

See how the boat performs, and then post the pitch and diameter (should be stamped on the hub).

 

[EL-BATO]

We have an '88 Thundercraft 16.5" bowrider, 3.0L OMC Cobra. 2300LBS with a full tank of gas and trailer.

OEM Prop was 14" x 19 pitch. Blades were a bit "narrower" and "taller" looking. If memory serves, GPS speeds are 30MPH @ 3500 RPM and 42MPH @ WOT (4600ish RPM)

Recently bought a Michigan prop 13" x 21 pitch. Blades seem a bit "fatter". Bit slower getting out of the water if the boat's loaded however I gained 7 MPH at cruising (3500 RMP) GPS Speeds are: 30 MPH @ 3000 RPM, 37 MPH @ 3500 RPM and 40MPH @ WOT (4000ish RPM).

Hope this helps!

 

[jimmbo]

Well the 21 is overloading your engine, 4000 rpm is below the recommended range. I don't know what the recommended range is but is usually 4200 - 4600, or 4400 - 4800. You need to know that info. Another clue showing the 21 is too big, is you top speed is actually lower with a higher pitch prop. At any given rpm it will be faster than the 19, but it is too big to allow the engine to get to its rated HP. Your old prop wasn't too bad

 

[EL-BATO]

Fair enough Jimmbo however I never cruise at WOT... In fact I spend very little time in that RPM range, i'm usually in the 30-35 RPM Where I got the most gain. The engine hardly feels overloaded at those RPMs.

 

[Bondo]

Fair enough Jimmbo however I never cruise at WOT... In fact I spend very little time in that RPM range, i'm usually in the 30-35 RPM Where I got the most gain. The engine hardly feels overloaded at those RPMs.

Ayuh,..... But the point is,... Yer luggin' the motor, All the time, regardless whether ya run Wot or not,....

If the motor can't ever make the recommended rpms at Wot, it's Luggin',.... All the time,....
Guaranteed to eventually burn a hole through a piston, or smoke the exhaust valves,....

 

[Bondo]

The Prop on it looks like it is too small for the boat.

Ayuh,.... Welcome Aboard,..... I'm gonna Guess ya got a hold-over Stringer 400 drive, rather than a Cobra drive,....

The change-over year was '85, 'n some '86 boats still came with the older discontinued Stringer drives,....

Post a picture,.....

 

[jimmbo]

We have an '88 Thundercraft 16.5" bowrider, 3.0L OMC Cobra. 2300LBS with a full tank of gas and trailer.

OEM Prop was 14" x 19 pitch. Blades were a bit "narrower" and "taller" looking. If memory serves, GPS speeds are 30MPH @ 3500 RPM and 42MPH @ WOT (4600ish RPM)

Recently bought a Michigan prop 13" x 21 pitch. Blades seem a bit "fatter". Bit slower getting out of the water if the boat's loaded however I gained 7 MPH at cruising (3500 RMP) GPS Speeds are: 30 MPH @ 3000 RPM, 37 MPH @ 3500 RPM and 40MPH @ WOT (4000ish RPM).

Hope this helps!

ElBato You should have started you own thread instead of Hijacking MrGeon1s