Engine tune

Airboats with smaller powerplants.
Merwin
Southern Airboat Member
Posts: 3
Joined: Sat Aug 20, 2016 10:00 am

Engine tune

Postby Merwin » Sat Sep 15, 2018 8:30 pm

I have a 35hp vanguard with govenor 66 in 3 blade prop with reduction started prop pitch at 10 deg. full throttel Iam only getting 2000rpms I need to get to 3500 for max hp so more or less pitch? how do I get to 3500 rpms

Aeon
Southern Airboat Member
Posts: 135
Joined: Mon Jan 24, 2011 11:11 pm
Location: Orange county-- the wrong one. I'm in California

Re: Engine tune

Postby Aeon » Sat Sep 15, 2018 8:42 pm

less pitch and the motor will spin faster. set the pitch with an angle gauge so you get them all the same.
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

SWAMPHUNTER45
Site Supporter - III
Site Supporter - III
Posts: 2672
Joined: Thu Nov 21, 2013 11:38 am
Location: Naturecoast, Florida

Re: Engine tune

Postby SWAMPHUNTER45 » Sun Sep 16, 2018 8:26 am

If you don't have an angle finder or struggle to grasp that process there is another way to make certain your blades are all pitched equal. You can take a measurement from the trailing (back) edge of the blade to a fixed point on the boats transom. Measure 2-4 inches from the tip and place a ink Mark, do that equally to all the blades so you measure from the same position. Then Mark your position on the hull and develop a method to read the distance between 2 points with skill. Pull the plug wires off because your going to need to turn the blades to measure. Safety first. We try to keep the blades as true to perfect as possible and 1/64th is very good 1/32 would be the outer limit but you don't want big deviations like 1/8 or 1/4 inch. Strive to set the blades perfect it will be better for the engine and prop. Be aware often times depending on hub design as you tighten or torque the hub the blade position will shift and you must monitor and readjust.

Taking pitch out lessens the blades angle of attack making it look thinner from the side. Try going with 1/4 inch less pitch and see what type rpm jump you get. Be aware not to over spin your blades in the process.

Hope this helps.

User avatar
mojoe
Southern Airboat Member
Posts: 944
Joined: Thu Jul 23, 2009 8:55 pm
Location: Catfish Motel

Re: Engine tune

Postby mojoe » Sun Sep 16, 2018 8:59 am

Use a zip tie. Just wrap it around the cage wire so that it “points” toward the trailing edge of the prop. Adjust it so it just touches the trailing edge of one blade. Cut off any excess if necessary. You now have a point of reference. You can add pitch and remove pitch by looking at the trailing edge in relation to that zip tie. Then once you have changed the pitch on one blade, move the zip tie until it just touches the trailing edge of the blade you just adjusted. Now adjust the other blades to that new point of reference.

It works with just the zip tie in a pinch.
Using a level to set the prop perfectly horizontal, then doing this has smoothed out props that we couldn’t get to feel right using a digital protractor.

I think prop blades are not perfect, just because the face of the blades are at the same angle (same pitch using a protractor) doesn’t mean the blades will track the same. Using a fixed point of reference I have found to make for a much smoother feel, particularly on a 2 blade.

On the river, it’s a neat trick using just the zip tie. On my boat at home, I use a Warp Drive bubble level and an angle finder to do initial set up, then use the zit tie to fine tune if there is any vibration.
Mark 7:9

Merwin
Southern Airboat Member
Posts: 3
Joined: Sat Aug 20, 2016 10:00 am

Re: Engine tune

Postby Merwin » Sun Sep 16, 2018 9:04 pm

ok i do understand how and have pitched my prop with an angel gauge to fifteen degrees but it does not seem to change my rpm i just have a cheep digitel tach iam going to change? the kind you wraparound the plug wire ? but i think i have a govoner issue went from 10 degrey pitch to 15 got more power never lost or gained any rpm. with or without a load i cant seem to get this motor over 1800 rpm

Aeon
Southern Airboat Member
Posts: 135
Joined: Mon Jan 24, 2011 11:11 pm
Location: Orange county-- the wrong one. I'm in California

Re: Engine tune

Postby Aeon » Sun Sep 16, 2018 9:34 pm

take the prop off... spin motor as fast as you can. if its not getting up to 4200 its broke. I have the same motor on my mud boat and they sometimes do that. you want to tune the prop to spin at 3600rpm at full throttle

clean the carb and make sure the plug wires are not grounding. This gas we have now goes bad fast and can plug up stuff. the fact that you piched the prop more and it ran the same speed could mean the gov is broke
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

Air canada
Southern Airboat Member
Posts: 23
Joined: Sun Oct 29, 2017 2:46 pm

Re: Engine tune

Postby Air canada » Sun Sep 23, 2018 9:09 pm

I have same motor on my mini pro 116 First I'd suggest remove governor! Look up hover hawk in U.K. Vanguard governor removal On YouTube and they show you how to remove governor mine came a part and cause damage . You don't need the governor anyways because you control your max rpm with prop pitch and the tiny tachometer is preatty accurate I'd keep that one if that what you have . And as for setting prop I use the level in the compass app on my iPhone pic a point on prop do it on flat surface and set pitch that way
:canada:


Return to “Mini-Airboats”

Who is online

Users browsing this forum: No registered users and 1 guest