I have a 4.3L V6 vortec crate motor with an edelbrock performer aluminum intake and a holley 390cfm carb. Currently I am running this on a 10ft alumitech A-style hull with 1/8" bottom and 1/8" sides. It will run dry fairly well on grass and gravel however when I hit the sand from the water I am not going anywhere any longer and need to get out the shovel and get to work making a canal of water under the boat to get back to the river. I forgot to mention that I also have a 66" cypress water walker prop on it. I have adjusted it many times to stop the motor anywhere from 2700 to 3100 RPM and have not noticed any amazing results. The only other solution is to put a larger motor on it or to add a gear box. Is there anyone out there who could recommend what ratio to go with for this particular combination? Also I am wondering if it will increase my gas mileage by preventing the motor from working as hard as it does as a direct drive. I would really like to hear from some people who are currently or have experienced the 4.3L vortec with a gear box IN ACTION.
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4.3L vortec V6 gear box ratio suggestions
- Thread starter catfish
- Start date
dantheairboatman
Well-known member
I run sbc an olds on different stingers ratios and different props.but not a 4.3 bought one to build but ended up selling it.My opinion is start at 2.38 softdrive with a 78in falcon or 2.684 or 2.88 with 78in sw Sen. Make sure you get a soft drive because the firing events are farther apart and will create more gear noise than 8 . Your heading in the right direction,let the gear do the work and take some pressure of the motor witch will result in better gas mileage.
Waterthunder
Well-known member
I have built several 4.3 V6's and there is no better box for that motor then a 2.68 a 2.68 on a 4.3 will perform as good if not better then a comparable small block with a 2.38 or 2to1!
AirRanger
Well-known member
Catfish, Let me start by saying that I just finished building my first airboat (w/ help of a few good friends). It just so happens that it is a 4.3 Vortec with a 1.77 to 1 gear reduction. I first ran it on a lake last week, it ran well but I did have some rookie mistakes to overcome. After going back and fixing up a few things I was able to run it again just today this time dry as a bone (green grass). I can not tell you how impressed I am . 72" Warp drive 6 blade around 3900-4000 rpm on the motor. 13' 6" fiberglass open hull (Apache). So good luck with your set up.
Hey Catfish, We use the 4.3 Vortec on a lot of boats, mostly 13 footers. the 10
hull is a little on the small side for good buoyance.
We set up the 4.3 V6 with a 2.37 gear an a 74 inch Maximus Prop. If I had to
use a 78 inch prop, I would probably use a 2.68 gear, but a small boat with a 78 inch
prop means a bigger cage, engine mounted higher, and more running on the nose
when running ground. The shorter Prop let's you lower your engine without putting
too much prop below the transom as well as add more pitch to your prop. The results
are a better running boat in the water and on the ground. At WOT, 5000 RPM, the
prop is turning 2109, witch is excellent with the 74 inch Maximus, the 78 inch would
be set at 4 inches less pitch. Chuck
hull is a little on the small side for good buoyance.
We set up the 4.3 V6 with a 2.37 gear an a 74 inch Maximus Prop. If I had to
use a 78 inch prop, I would probably use a 2.68 gear, but a small boat with a 78 inch
prop means a bigger cage, engine mounted higher, and more running on the nose
when running ground. The shorter Prop let's you lower your engine without putting
too much prop below the transom as well as add more pitch to your prop. The results
are a better running boat in the water and on the ground. At WOT, 5000 RPM, the
prop is turning 2109, witch is excellent with the 74 inch Maximus, the 78 inch would
be set at 4 inches less pitch. Chuck