Rollbar's (Slow) Mini Build.

Airboats with smaller powerplants.
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Rollbar1
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Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Sat May 07, 2016 8:51 pm

Well I'm gathering parts and the NOS 4a084 is being shipped next week.
So far gathered up a cage and seating platforms for Peach and I. Also picked up a 20' dual axle aluminum trailer which I have to modify for the boat which will be 12'x approx 60 or 72".

The rigging is off a open boat but I will probably have to modify it or ?
The trailer is 5' wide, inside fender to inside fender.
I plan on cutting it down and lowering the fenders or using the squared off ones.
I might have to make a "L" bracket and add a 2x6 to each side of the main rail channel of the trailer for width.
One thing I like is it is very light and I can move it around the way it sits and being cut shorter, it will be nice.
Less weight for me to pull w/my Jeep CJ8/and CJ7.

So here we go on the slow build.

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kwanjangnihm
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Re: Rollbar's (Slow) Mini Build.

Postby kwanjangnihm » Sun May 08, 2016 6:58 am

Whats the horsepower & max rpm on the NOS 4a084 engine?
:rebel:
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Sun May 08, 2016 2:39 pm

kwanjangnihm wrote:Whats the horsepower & max rpm on the NOS 4a084 engine?
:rebel:


40-50hp at Sea Level depending on how how set it up I was told but more to the 50 mark I guess if you use a Solex carb and a tuned exhaust.

Now the MFG/Military rate them at 20hp but that is a cruising altitude/up in the air. 3,600rpm all day long.

I don't know the exact number, but when stripped down, some are saying they weigh about 125lbs and with the right prop/reduction gear you can run dry w/two people.
I know a guy in MS that has two left )NOS) and they are $600.00/$250.00 shipping.
I also met a guy local who said he has some but I didn't ask the price.
You must use a good oil cooler (15 row) and I have some oil filter numbers from the other forum whereas you can add up to a 2qt oil filter for more volume and cooling.

This is quoted from the 084 experimenters Yahoo group.

The engines were tested at TEN thousand feet at 107 degrees that they were
tested at.
> > These engines were run at full load for one thousand five hundred
> > hours, and THEN dynoed to insure that they pulled the rated power at
> > those conditions.
> > AFTER the dyno test, they were taken apart, and the parts were
> > measured for wear. If the sample engines did not BOTH make the rated
> > power, AND pass the wear test, the ENTIRE shipment of engines was sent
> > back.


a. General.
Engine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41084-2, -3 and -4
Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 cycle gasoline powered
Number of cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 (horizontally apposed)
Horse power rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 at 3600 r.p.m.
Fuel pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm 3.0-4.5 psi outlet pressure
Air cleaner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dry models 4A084-2, -3 and -4
Spark plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Shielded
Gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-.033 in. (.071-.083 cm)
Magneto contact
Gap, Fairbanks Morse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..015-.019 in. (.030-.48 cm)
Gap, Slick Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .008-.012 in. (.020-.030 cm)
Valve tappet clearance cold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..007-.009 in. (.017-.027 cm)
(Intake and exhaust)
Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Centrifugal
Oil capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 quarts (4 1/2 gts. with oil filter change)
Alternator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 volts alternating current (ac)
Starter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 volts direct current (dc)
Regulator-Rectifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 28.5 ± .5 volts at 1.5 amps
Firing order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1-4-2-3
b. Dimensions and Weight Models 4A084, -3 and -4.
Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 in. (50.8 cm)
Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.50 in. (72.4 cm)
Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 22.10 in. (56.13 cm)


Links:
http://miniairboatassoc.com/084/4A084a.pdf
http://miniairboatassoc.com/084/4A084b.pdf
http://miniairboatassoc.com/084/4A084c.pdf
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Sun May 08, 2016 3:06 pm

Does anyone have some dimensions/size on exhaust that they may have used w/this motor (4a084)?

Wanting to build a header type exhaust and not sure of the size pipe and still function well/some back pressure etc.
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Olf Art
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Re: Rollbar's (Slow) Mini Build.

Postby Olf Art » Sun May 08, 2016 7:38 pm

Rollbar1 wrote:Does anyone have some dimensions/size on exhaust that they may have used w/this motor (4a084)?
Wanting to build a header type exhaust and not sure of the size pipe and still function well/some back pressure etc.

How eaten up are you with the idea of dropping this engine into your boat 'as delivered'? There are a lot of very cool things that can be done to those engines for not a lot of money if you're handy.
All of those Continental engines are way under carbureted (I had a couple of the little 4AO-32's) because they were designed to run on practically skunk gasoline. The potential in them is only limited by your imagination and your wallet.
However ..... have you considered buying a run-out O-235 Lycoming (approximately 115 hp.) that will easily run trouble free for another 10 years, and was designed to turn a prop from day #1? You're at a point in this build where you can continue to think these kinds of things through.
"I know not what tomorrow may bring, but I know Who brings tomorrow."
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Sun May 08, 2016 7:49 pm

Olf Art wrote:
Rollbar1 wrote:Does anyone have some dimensions/size on exhaust that they may have used w/this motor (4a084)?
Wanting to build a header type exhaust and not sure of the size pipe and still function well/some back pressure etc.


How eaten up are you with the idea of dropping this engine into your boat 'as delivered'? There are a lot of very cool things that can be done to those engines for not a lot of money if you're handy.
All of those Continental engines are way under carbureted (I had a couple of the little 4AO-32's) because they were designed to run on practically skunk gasoline. The potential in them is only limited by your imagination and your wallet.


Well, I bought one, NOS, and I would like to run it seeing they are cheap to fit and cheap to run. I also will have to go DD for a while with any motor I use. I do have to bring the exhaust out the back/boat from what I learned (total novice here on ABoats). I would have to get a carb and I heard the VW carb/Solex was a good one to get.


However ..... have you considered buying a run-out O-235 Lycoming (approximately 115 hp.) that will easily run trouble free for another 10 years, and was designed to turn a prop from day #1? You're at a point in this build where you can continue to think these kinds of things through.


Can these run on pump gas? Wouldn't even know where to buy and hopefully I can get my money back out of the 084 first.

Thanks for the thought/tip,
Jim

P.S. Some info/tips on the 0-235. Scroll down about an inch to see the 0-235's heading.
https://www.scribd.com/doc/71681743/19/ ... 235-Engine
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Olf Art
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Re: Rollbar's (Slow) Mini Build.

Postby Olf Art » Sun May 08, 2016 8:43 pm

Rollbar1 wrote:Can these run on pump gas? Wouldn't even know where to buy and hopefully I can get my money back out of the 084 first.

Thanks for the thought/tip,
Jim

P.S. Some info/tips on the 0-235. Scroll down about an inch to see the 0-235's heading.
https://www.scribd.com/doc/71681743/19/ ... 235-Engine

When I was a kid I soloed in a little Piper Colt. My dad ran a gas station and garage in our little farming community and I'd take a 5 gal. gas can of Mobil regular to the airport with me when I wanted to go flying. The A-65 and A-100 Continentals were just fine on pump gas. Without knowing I'd guess that an O-235 would be too. Surely not more than 93 octane .... 80/87 was very common back then.
WWII radials needed 115/145 ..... that stuff was a guaranteed buzz just gassing up the airplane! Woo hoo!!
"I know not what tomorrow may bring, but I know Who brings tomorrow."
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Sun May 08, 2016 10:09 pm

Olf Art wrote:
Rollbar1 wrote:Can these run on pump gas? Wouldn't even know where to buy and hopefully I can get my money back out of the 084 first.

Thanks for the thought/tip,
Jim

P.S. Some info/tips on the 0-235. Scroll down about an inch to see the 0-235's heading.
https://www.scribd.com/doc/71681743/19/ ... 235-Engine

When I was a kid I soloed in a little Piper Colt. My dad ran a gas station and garage in our little farming community and I'd take a 5 gal. gas can of Mobil regular to the airport with me when I wanted to go flying. The A-65 and A-100 Continentals were just fine on pump gas. Without knowing I'd guess that an O-235 would be too. Surely not more than 93 octane .... 80/87 was very common back then.
WWII radials needed 115/145 ..... that stuff was a guaranteed buzz just gassing up the airplane! Woo hoo!!


Thanks, wasn't 100% sure seeing a lot run the AvGas on the forums.
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PeaRiverOpossum
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Re: Rollbar's (Slow) Mini Build.

Postby PeaRiverOpossum » Mon May 09, 2016 8:46 am

Should be a cool little build. I look forward to watching your progress. Thanks for taking the time to post.

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Caddellwelding
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Re: Rollbar's (Slow) Mini Build.

Postby Caddellwelding » Mon May 09, 2016 11:35 am

I've got a rotax 503 dual carb with electric start


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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Mon May 09, 2016 5:44 pm

Caddellwelding wrote:I've got a rotax 503 dual carb with electric start
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I was wondering if I could do a dual carb setup on the 084, but might be better to just install a solex or small weber. I'll have to check CFM on the stock one as well as the VW Solex carb and see what they put out.
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Fri May 27, 2016 3:59 pm

Ok received the motor today. I turned it some by hand and it is free. Now I have to figure out what I have to take off. I just wanted to post pictures of it complete/how one would receive it in case others were wondering upon purchase.

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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Fri May 27, 2016 4:01 pm

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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Fri May 27, 2016 4:03 pm

Have to look in the manual to find out what this bowl is for.

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southern safaris
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Re: Rollbar's (Slow) Mini Build.

Postby southern safaris » Fri May 27, 2016 4:44 pm

Could be wrong but isn't that a fuel strainer bowl like on an old tractor so you can see what's in it
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Re: Rollbar's (Slow) Mini Build.

Postby barhopper » Fri May 27, 2016 5:16 pm

I like the pull rope

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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Fri May 27, 2016 6:33 pm

Received to prop today.

27.5"-total 59"
10* pitch blocks.
3100 max rpm.

Here are some CFM calculations based on what I have, and what rpm I can run these blades (thanks to Deano).

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Things are coming together.

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The blades came off this boat and they were behind a 084.




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Last edited by Rollbar1 on Fri May 27, 2016 10:43 pm, edited 4 times in total.
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Fri May 27, 2016 6:34 pm

southern safaris wrote:Could be wrong but isn't that a fuel strainer bowl like on an old tractor so you can see what's in it


Might be.


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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Sat May 28, 2016 1:00 pm

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Caddellwelding
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Re: Rollbar's (Slow) Mini Build.

Postby Caddellwelding » Sat May 28, 2016 10:52 pm

I'm ready to see it run!


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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Thu Jun 16, 2016 2:29 pm

Score!
Bought a twin jet ski trailer (excellent shape with buddy bearings and new spare) and Ultralight Full Lotus Floats with spare bladders for $100.00
Jet ski trailer is 13'. 10' to the tongue and a 3' tongue.
6'10" inside fender to fender.
Now I have to decide to keep it with minimal work needed or keep the 20' trailer and a lot of work needed. I was going to make the 20' a dual trailer for also towing a Jeep if needed.
Those Lotus floats are pretty nice so I'll have to research those because they will be for sale.

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Re: Rollbar's (Slow) Mini Build.

Postby airjohn81 » Thu Jun 16, 2016 2:53 pm

i had 2 084's on 10x6 mini gore hulls... #1 thing you MUST do is run an oil cooler !!!!!!!!!!!!!!!! if not they are a valve seat dropping machine !! i modified my intake for a solix 32 pic carb off the vw's w accelerator pump an it woke the lil **** up !!!!(can walk ya through it !!) i also made custom manifolds (for noise reduction )an it actually boosted power !! then i had a 1.7-1 4 belt redrive made an that lil B hulled asss!!!( high 30"s -40mpg depending on water) 1 person i could run dry w a head start.. when i ran em direct drive (arrow prop makes the adapter an re drive's ) i ran the ultra prop 3 blade max diameter an w the re drive i ran the 4 blade.. it was a fun , reliable, an easy motor to work on .. i highly recommend the re drive youll be really happy.. ohh and i ran 93 octane when i first was running it an then switched to 100ll an i never ran car gas again... what a difference in head temps alone !! have fun an hit me up if ya ever need anything.. i love my 084's
:old_glory: :florida: :rebel:

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airjohn81
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Re: Rollbar's (Slow) Mini Build.

Postby airjohn81 » Thu Jun 16, 2016 2:53 pm

my profile pic is one of them i had.. that was the re drive one !!

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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Thu Jun 16, 2016 4:54 pm

airjohn81 wrote:i had 2 084's on 10x6 mini gore hulls... #1 thing you MUST do is run an oil cooler !!!!!!!!!!!!!!!! if not they are a valve seat dropping machine !! i modified my intake for a solix 32 pic carb off the vw's w accelerator pump an it woke the lil **** up !!!!(can walk ya through it !!) i also made custom manifolds (for noise reduction )an it actually boosted power !! then i had a 1.7-1 4 belt redrive made an that lil B hulled asss!!!( high 30"s -40mpg depending on water) 1 person i could run dry w a head start.. when i ran em direct drive (arrow prop makes the adapter an re drive's ) i ran the ultra prop 3 blade max diameter an w the re drive i ran the 4 blade.. it was a fun , reliable, an easy motor to work on .. i highly recommend the re drive youll be really happy.. ohh and i ran 93 octane when i first was running it an then switched to 100ll an i never ran car gas again... what a difference in head temps alone !! have fun an hit me up if ya ever need anything.. i love my 084's
:old_glory: :florida: :rebel:


Thank you,
I'll probably need some guidance on what to remove from the motor/extra things not needed, once I get to that point, and a few other things but thanks again for the offer.

Jim :old_glory: :rebel: :florida:
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Rollbar1
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Re: Rollbar's (Slow) Mini Build.

Postby Rollbar1 » Thu Jun 16, 2016 6:29 pm

I'm thinking I can extend this trailers rear a few feet to accommodate a 10'-12' boat.
Maybe some channel or wood.

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