John Fenner
Well-known member
Entirely too much cfm carb!
The intake is too much as well, a stock TBI intake would be better.
The intake is too much as well, a stock TBI intake would be better.
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PROP SEARCH
- Thread starter Colton.h
- Start date
Ok that’s what I was afraid of. Thanks for the tip.
Slidin Gator
Well-known member
You are looking for a 1 or 2 bbl carb about 300 CFM.
You can make or buy an adapter, but that 4 bbl marine intake is a heavy chunk of cast iron, I have one, it's the heaviest 4.3 intake they make. Aluminum TBI Intake accomplishes two goals in one. You will still need to make/buy a plate adapter for a 1 or 2 bbl.
https://www.edelbrock.com/performer-small-block-chevy-4-3l-t-b-i-v6-intake-manifold-3713.html
The number 14071177 comes up as a 85-86 Mercury Marine engine. Coupled with the marine intake it sounds like you have the marine engine setup, cam etc., all good.
Slidin Gator
Well-known member
Be careful about 4.3 years when buying parts. 80's and early 90's were original 4.3, 93/94 on most everything was Vortec. Vortec heads use a different intake manifold, the bolt pattern intake to heads is not interchangeable. The A Frankenstein stroker 4.3 80's block with Vortec Heads is the limit of the 4.3, but hopefully you got a runnable long block.
I suggest focusing on getting the engine running as she sits before spending money. You don't need a prop to fire it up, it's just like a car/truck in neutral. If you can get the engine to fire and turn two revolutions on starting fluid, you know she ain't locked up. If you can get her to idle nice you are confirming it has the OEM marine cam (what you want) vs. someone putting in a "muthathumpa" cam to go with the double pumper 700+ CFM carb.
I suggest focusing on getting the engine running as she sits before spending money. You don't need a prop to fire it up, it's just like a car/truck in neutral. If you can get the engine to fire and turn two revolutions on starting fluid, you know she ain't locked up. If you can get her to idle nice you are confirming it has the OEM marine cam (what you want) vs. someone putting in a "muthathumpa" cam to go with the double pumper 700+ CFM carb.
Ok, gotcha.
We were able to actually get it running a few weeks ago. I fixed all the wires, fuel tank, hoses, batteries, throttle system, ext, to where she'll fire right up when the battery is charged. I bought a cheap RPM gauge just to test it out, and It's not too accurate, so I'll have to upgrade.
I still need to do some work, like nav lights and horn, but the prop is next on the list to buy.
Slidin Gator
Well-known member
I may have not mathed correctly, 6 foot hull is 72". 58" can be stretched, what is limiting your prop diameter to 58"? That plywood box? I see Warp drive goes down to 64" without trimming. If you can fit that into the existing cage, that's a solution. 62" diameter with an inch of trimming works too.
Assume 100-125 Hp for prop selection. I would opt for even number of blades to minimize vibration on DD V6 (odd number of fires per rev). Special bonus, on Warp drive with even number of blades, if one blade is damaged you can delete the opposite and have something to run home on. I vote 4 blade Warp.
Also talk to Sensenich and Whirlwind, Whirlwind (Ww) in particular. Ww has been acquired by Hartzel, they might have some other aviation pusher prop options.
Assume 100-125 Hp for prop selection. I would opt for even number of blades to minimize vibration on DD V6 (odd number of fires per rev). Special bonus, on Warp drive with even number of blades, if one blade is damaged you can delete the opposite and have something to run home on. I vote 4 blade Warp.
Also talk to Sensenich and Whirlwind, Whirlwind (Ww) in particular. Ww has been acquired by Hartzel, they might have some other aviation pusher prop options.
It's not the box; that's where we temporarily have our batteries. We were able to do some modifications to where I believe it will fit a 68in. I don't know how much angle a prop blade has, so I could do some more mods if a 68 doesn't fit, but I think it would.
Ok, sounds good, I'll look into that. I saw Warp Drive 4 blade is out of stock, so I may have to wait for that. I emailed them, but haven't heard back just yet on what would work for my setup and why the original email said no.
Appreciate the advice
Ok, sounds good, I'll look into that. I saw Warp Drive 4 blade is out of stock, so I may have to wait for that. I emailed them, but haven't heard back just yet on what would work for my setup and why the original email said no.
Appreciate the advice
Slidin Gator
Well-known member
Batteries as in multiple on stbd stern is a big nope! Direct Drive Prop to Port means the boat Torque Rolls to Stbd. Move the batteries to the port side somewhere around your seat stand. Going forward you may find that moving the trolling motor battery to forward port improves balance, but don't start there.
Imagine staring at that boat from the stern sitting in water, now apply 250 ft-lbs of CW torque at the prop hub.
Slidin Gator
Well-known member
3 blades is the worst choice for vibration on a V6 (other than 1 blade). 2 blades is the most efficient for wider blades and push, but this gives torque roll, which you need to avoid.
5 Blade also works with a V6 well for vibration purposes. Do not consider 6!
Notice the old Radial engines were always an odd number of cylinders?
John Fenner
Well-known member
As with running 3 bladed units on 6 cylinder AC without counterweights, harmonics are not good.
Slidin Gator
Well-known member
Here is my 4.3 Vortec setup. A sewing machine motor would run the rig, 2,4,8:1. Notice the heavy cast iron marine intake, weight's not such a deal on this rig.
DDPWRD
Well-known member
Not to steal the thread but to ask a question about your comment. I’m fixing to switch to a 3bld H on my 0-470 is that not a good option?
John Fenner
Well-known member
You can take the chance.
John Fenner
Well-known member
I'll second that notion.
Slidin Gator
Well-known member
For starters, a V6 is a different animal than an aviation Boxer 6 cylinder aviation. V6 engines are naturally unbalanced, GM knows this and they added a counterbalance shaft to the 4.3 (being discussed here) when they switched to the Vortec setup mid 90's (that you should definitely remove from any hot rod/airboat engine). Some of the newer and larger V6 4 stroke outboards also utilize counterbalance solutions.
180 degree boxer engines are a different animal, but vibration concerns remain. If a 6 cylinder aviation engine is balanced a 3 blade can work really well on 6-cylinder aviation boxer engine, a buddy of mine runs a 3-blade whisper tip on a factory balanced Lycoming O-580 and it is a great package. In other words, it can go really well, or not. It is worth noting that 3 blade props are used quite regularly on aviation 6 cylinders. But... Those aviation packages are tested and FAA approved.
Aviation airboat engines and the parts strapped to them are more typically built from a hodge podge of used parts with balance weights often removed. The engine balance is unknown. When the 6 cylinder/3blade package works, it works great, when it goes wrong it goes bad wrong. 2 blade prop on 6 cylinder (and 3 blade on 4 cylinder) aviation setups will have a base level of vibration, but they are unlikely to team up for really bad base and harmonic vibrations.
The term "Harmonics" is a catch all term for "Vibration" on this board. Strictly speaking you can have a Vibration and you can have "Harmonic Vibrations". Harmonics are always an octave or more above or below the base driving vibration. Using different cylinder vs prop blade vs gear ratios is a means to accept a level of vibration (while never being fully balanced) by spreading out the vibration sources in a manner that makes damaging harmonic frequencies unlikely.
For more on this topic I suggest this thread.
Lets talk about harmonics
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Slidin Gator
Well-known member
Slidin Gator
Well-known member
Gee, why would this thing that is supposed to counteract vibration break at the 1/2" diameter neck???
John Fenner
Well-known member
I guess this conversation should include the odd fire Buick 231,, do a typical tuneup and the misfire is worse, that one had the best mechanics chase their tail.Gee, why would this thing that is supposed to counteract vibration break at the 1/2" diameter neck???
Slidin Gator
Well-known member
No cross fire for me.
The 4.3 Vortec has a counter balance shaft under the intake. That shaft is as small as ~1/2" near the forward bearing.
It's a counterbalance shaft! The purpose is to FIGHT the vibration, emphasis on FIGHT.
So it take a hell of a load if you are turning a Vortec V6 into the 5-6K+ range and has a reputation for coming apart on the strip (usually with boost).