Prop pitch for my Starcraft Nassau

[tgp***]

Now that I have a second parts motor(1967 Merc 650), I found I have a second prop w/ a 19 pitch. The one on the boat now is a 15p. Would one be better than the other for some reason? I was happy with test run I did. If I did change it, I wouldn't be able to test the difference anyway, as I have no speedo or tach.

What are others running on similar boats (1966 Starcraft Nassau 16')??

Thanks.

 

[fshngho]

Re: Prop pitch for my Starcraft Nassau

TGP, you would notice the difference. If you didn't have any problems with the hole shot then you should try the 19. It is just like a car's rear. The lower the pitch the more torque you will have, i.e. faster hole shot & easier towing of skiers/tubers. You will have less speed on top end as your rpm's pick up quick. If you go to the 19 you lose some torque on starts, harder to pull people & slower hole shot, but you pick up speed or cruise at same speed as now with lower rpm's.

 

[Bob Gilvary]

Re: Prop pitch for my Starcraft Nassau

You need to be careful you don't over rev because of too little pitch, or lug/strain the engine with too much pitch.

Either issue can and will in time, blow the engine. Best investment is a tach!

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

Will any tach work? or are there ones specific to outboard motors?

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

Would something like this work on 1967 650 Merc?

http://cgi.ebay.com/ebaymotors/Hour...3501675QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

 

[GLG fishing]

Re: Prop pitch for my Starcraft Nassau

Sure can?t see why not.
If you only want to hook it up temporary to see what your rpm is.
If you want a permanent solution get one that you can mount in or on the dash.
Something that can take the weather.
There should be a grey wire in your harness that is for a tachometer.

GLG

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

Sure can?t see why not.
If you only want to hook it up temporary to see what your rpm is.
If you want a permanent solution get one that you can mount in or on the dash.
Something that can take the weather.
There should be a grey wire in your harness that is for a tachometer.

GLG

I would'nt mind mounting on the dash, but don't want to cut a hole in it for one, that I know. I need to figure out the whole pole thing first.

 

[fshngho]

Re: Prop pitch for my Starcraft Nassau

GLG is right on. The two most important guages that should be on a boat is RPM and Water Pressure. At least for OB's
Money is tight for everyone, but get the best guages you can afford. It may save your motor one day, (or every time its running)

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

GLG is right on. The two most important guages that should be on a boat is RPM and Water Pressure. At least for OB's

Not sure, there's a connection for a water pressure guage on my motor that I'm aware of. I need a little more information on the water pressure guage, and the water pressure of of what??.... What sender are you connecting it to????

What can you tell me, specificly.

Thanks

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

http://www.maxrules.com/propindex.html
Mercury prop charts found. It took severals hours of internet searching but see the attached link. The charts show prop numbers for motor models, and will give speed range for size of boat and load, for 1974 and earlier.

I'm looking for information regaurding the letters at the end of the prop numbers.

I found one of my props the 15 pitch 48-37900 (12.5 inch 3 blade prop),but the letters A3L at the end of the number on my prop, does apear on the list.

Does anyone know what the A1, A2 or A3 athe end of prop numbers mean, or relates to? or What the A or C at the beginning of the number mean?

My 19 pitch prop number is 48-65588 A1 19P, is not on the list but I believe it to be a 13-inch. This also is a 3 blade prop.

 

[fshngho]

Re: Prop pitch for my Starcraft Nassau

Most OB's have water temp sending units that will let you know the motor is overheating....after its too late. A water pressure unit will let you know if you are getting water and keeping the motor cool. Anything from a bad impellar to stuff blocking the inlets or passages in the motor would effect the pressure. Honestly don't know where to do a hook-up, because that depends on the motor, but my guess is anywhere the sending unit is mounted. I believe the pressure isn't great, about 5-12 but the idea is to see if it decreases from the normal pressure.

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

Well it gives me a starting point. I'll try one of the other forum's.

thanks

 

[tgp***]

Re: Prop pitch for my Starcraft Nassau

Anyone running an old Merc outboard w/ a tach out there??

What pole setting do you use?

My motor is 67" Merc 650 with Thunderbolt Ignition, and I have the 3 wire connection coming from the front of the control box.

I'm looking at putting it in a tach cup and then mount on top the dash.

Bythe way, I found this site w/ a Merc prop chart for older merc outboards pre 1965 to 1974.
http://www.maxrules.com/propindex.html

Thanks