Prop Help for GF-16

[robbiro]

I finally got a prop wrench and pulled the prop on FIRST LIGHT (GF-16), The markings indicate that it is a Michigan Wheel Vortex C04 13. I am guessing that this is a 13 pitch??? The C is a model number . What is the 04??

The motor is a 1991 Johnnyrude 2 cyl 25 HP remote operation long shaft electric start. Is this the correct prop for this boat?? Last summer at idle speed by GPS I got 5 mph. at WOT it was 15.5. sounds a little low to me. Should it be more in the 10 1/2 to 11 range??

Thanks for any assistance in advance.

Keep on Buildin'
Robbie

[Cracker Larry]

That sounds real slow to me. My GF16 would run about 35 with a 25 Merc. I think I had a 15 pitch prop on mine, but could be mistaken, it's been a few years. The only real way to know if it's right is with a tachometer. The motor should turn about 5500 rpm when propped right. I temporarily installed a Tiny Tach that connects to a plug wire to get mine dialed in.

[Uncle D]

Tiny Tach are great aren't they!! You can also permanently install them too. They have 2 or 4 stroke tachs and the one I ordered had an hour meter. There nice on older motors that don't have electronic modules. I ordered a 15 ft. lead for mine and mounted it on the console.

[robbiro]

Thanks Uncle D and Larry. I am going to bite the bullet and run the prop and motor through a local establishment named "The Prop Shop" and let them see what I don't know (plenty ) about setting up the motor and checking the pitch of the prop. I may have something very minor not right about the throttle linkage or the prop may have been re-pitched before I got it!!! Rather let someone who does this day in and day out check it for me. Have had several guys that I fish with and friends recommend them to me. They do have a good rep with the local boating community.

Results when I get them.

Robbie

[robbiro]

Finally put a tach on it (Northern Tools, it was cheaper that tinytach and we have a store within 30 miles of here). At idle with load 700 rpm at WOT 4000 rpm. Speed still in the 15-17 range. Any ideas??

Robbie

[AtTheBrink]

Did you have your engine checked out? Maybe it is a carb issue? 4000rpm is aweful low. How does the motor run?

[robbiro]

It was checked before it was mounted on the boat. The current throttle connections were not used at that time. That might be part of the problem (mechanic error ) As far as the running of the motor: smooth, no misses, cranks easily, I am trying to not spend any more $$ than I have to. It will get me where I want to go, just not quite as fast. I know this will not keep up with the 250 Yammies, etc that the guys in my bass club use, but it would be nice to see 25 mph if possible.


Thanks for input Mike,will have to see about getting it checked next week
Robbie

[Cracker Larry]

Rob, that engine should run between 5000 and 6000 rpm WOT. If it doesn't, something is either wrong with the engine, or the prop has too much pitch. Ideal is about 5800 with a light load. See if you can find a dealer or somebody who can loan you a few props that are smaller in pitch for you to try. That boat should run an easy 30 mph with 25 hp. We clocked mine with a Merc 25 running into Crystal River with TomW and I, and Tom isn't a little guy. This was in a following chop, not flat water. 32 kts. Not mph, kts. That was with 18 gallons fuel, gear, ice, beer, lot of tackle, fish, not very many fish and 500 pounds of people.

[TRC886]

I'm running a 25 Merc on my 14' Grumman. Prop is an aluminum, 3 blade, 13" pitch. Estimated top speed with a moderately heavy load is 30-32 MPH. RPM is unknown but it "sounds about right", neither lugging nor screaming.