Old airboat, new driver, and problems

[StrongVet]

I've stalked these forums for some time but only tonight registered to post. I'm a newbie that is learning about airboats, engines, propellers, and horse trading all at the same time.

A buddy has some marsh land we like to hunt and want to take our kids out. We need transportation, so I bought an old Lone Star Trail Boss 14'x8' glass boat with a 454 BBC DD and 72" wood prop that seats 5. The boat was in bad shape but ran and the "price was right." I knew it would take money and work to get it good. I was right.

The hull has been completely reworked - new stringers, new transom, new glass, and Fasco 9xn 2000 SuperSlick applied to the bottom. I bedlined the inside. The cage, engine stand, and frame have all been inspected, repaired where needed, reinforced, sand blasted, and will soon be painted. The prop and rudders have been removed and I will be ordering new ones to replace them.

The problem comes from the engine. Even though it ran, I decided to take it to a local mechanic for inspection and rebuild. He found two cylinders with water damage and a crack in the block. Needless to say, I need a new powerplant. I am not an engines guy, nor am I a master welder. For ease of installation I would like to just bolt on another 454 BBC and be done with it. I have questions:

1. Will a BBC do what I need it to do, or do I need to plan for a different powerplant?
2. With that size boat, am I OK with DD or do I need to add reduction? And, if adding reduction, do I keep the BBC?
3. Where can I get a reliable BBC for an airboat and not break the bank getting it to Houston?
4. Am I asking the right questions?

Thanks for the pro advice.

- Kris in Houston

[radtech]

pics might help...also a weight on the boat. How did it run with the previous motor and was it modified from factory specs? I run a heavy 16x8 aluminum hull, heavy steel rigging, and a modified 500 Cad. Even with the weight issue, it runs dry fairly impressively. I should think your app would run well with the 454 depending on how you intend to ride. Short dry runs are easy, just have to get in some stick time to know what it and you are capable of. Longer runs depend on the ability of your boat to keep moving on the terrain you ride, though there is also an aspect of driver experience that can add to it.

[StrongVet]

I don't have a weight yet. I can lift the hull with another man, so I would guess it's in the range of 300-400 lbs empty. I will be weighing it once it can be trailered. Add the cage, seats, engine, fuel, my 200lb rear, etc. and I'm sure it adds up quickly. Short answer - I don't know but will try to find out.

It ran well with the previous motor, but realize that my frame of reference is small at best. The motor ran. The boat moved through the water and it seemed sufficient. But we did not run dry. The previous motor had been bored out 0.030 and seemed otherwise fairly stock but with a big carb. But again, not my area of expertise - working off what I have been told about it.

[SWAMPHUNTER45]

If running dry loaded is your goal then a gear drive will likely be a needed upgrade.

Cost wise staying direct drive is the lowest $ cost option.

If doing any modification (direct drive) to the engine your goal is to increase torque and gain power below 3,000 rpm so upgrades and changes need to be specific for that low rpm goal. Often times people bolt on components made for higher rpm gains and actually hurt their low end when running a direct drive build.

Focus on RV type components 1200 to 3000 rpm range when selecting for a direct drive.

[happy harold]

pick up a used 454 older good running motor home engine and ride. did that on one 10 years ago and its still running. will not run dry loaded.

[glades cat]

Welcome aboard, Kris.
You could switch to a small block with reduction and shave some pounds.
The boat looks very nice.

[goldhunter_2]

welcome aboard.

You mentioned "old lone star boat and wood prop" to carry your kids around first thing I have check is the wooden prop to be sure there is not damage or rot under the leading edges as those can explode and hurt the boat or people. A newer composite prop may be something to seriously consider there are extra money but you can usually find some good deals on used props.

if two guys can lift the whole boat hull at least you know the core isn't waterlogged but I think you will find your total weight heavier then you expect when you get it all together then loaded down with gear/decoys/kids/guns/dog etc etc. While direct drive would be the cheapest route you already have the boat apart and modifying the engine stand now would be the easiest time to do it, a gear box would increase the performance and allow you to carry the loads better. Again if you look around you can find pretty decent deals on used gearboxes in the SA classifieds now and then.

what ever you decide to with your new boat setup make sure the boat is going to be safe to make good memories with your kids. Also know your abilities as a operator as well as the boats capabilities , so get plenty of what we can stick time in shallow areas.

[StrongVet]

Thanks for all the feedback. I do plan to get a carbon prop - the old wooden one is going to be turned into a nice decoration for the garage wall.

Regarding going from a BBC to a SBC, how much are we talking about changing? What I mean is, will it bolt on the same and just be a matter of prop clearance and making sure it spins at the right height? Or will I have to cut off the old mounts on the stand and weld on new ones? SBCs seem to be easier to find these days. I could order a crate version and have a brand new rig ready to roll pretty quickly but for a price. If I could find an old RV running that might be a good place to go, too, although running dry loaded sounds sexy.

Again, thanks for the help.

[SWAMPHUNTER45]

Best thing to do is figure out your budget because this can get expensive fast...lol

You cant beat the lighter weight gear drive for running dry, there is no comparing.

Direct Drive $3,000 to $4500
Gear Drive $7,500 to $10,000+

Machine shop rebuild on your 454 apx. $2500 if nothing crazy maybe cheaper
Quality 2 blade composite prop new with hub under $2,000 maybe find a clean used $1,000

New Crate 383 around $4500
New Gear drive $2650 / used $1,500
3 blade prop quality composite new $2750 / used ? $1,800
Fabrication ? $200 to $1400

Can you make it cheaper yep but a fair estimate to consider in making your plans.

[JAMES]

Where do u get these prices your figuring . ^^ no machine shop that I know would build your 454 for 2500 bucks and you damn sure can't find her one of the 383 for 4500 I know because I just dropped 8kon a custom builtone The $4500 ones you see aret going to last long on airboat

[newoldglory]

It would help if you had an uncle in the repo business but other wise, welcome to airboating.

[OneBFC]

I think you should consider what you wish to do with this boat. As it stands, you are looking at replacing nearly everything if you want to to move 5 people and gear on soft ground.

Maybe you can move that many people on hard ground and good slick bottom with a DD setup, but you said marsh so I assume it is soft.

You likely can't just pop a reduction onto the engine you have because the rigging is most likely not built to allow additional driveline length.

Here is what I see you need to buy right now:

New propeller (2000 to 3000)
New reduction (2500 to 3500)
New engine (used to new at 400 to 600hp)(3000 to 10k)
Rigging (no clue)

You basically need to generate about 0.5 lbs of thrust for every 1.0 pounds of boat to ensure adequate dry capability across a wide range of conditions.

5 people on a big block boat with gear is going to be near 3000 lbs in my estimation. So, you need 1500 lbs of thrust. How you get that 1500 lbs is the puzzle people wrangle with.

Lastly, above all else, "setup" is king. Big power won't always result in a capable boat.

If I were in your shoes, I would sell what you have and look for a used boat that more closely matches your needs and test ride it in your marsh before paying for it.

Good luck!

[radtech]

Call around junk yards and see what is available. Might luck up on a deal. If your rigging isn't real heavy and in good shape, it could be modified to fit most car motors with just some cutting and rewelding. I can guarantee your boat weighs less than mine. I found a 500 Cadillac motor for $600 at a junk yard and tossed it in and ran it for over a year with no problems. With a good prop (recommend 72 or 74 water walker signature series, works great on mine...but that's my personal preference) and your light weight boat, should have no problem running most dry ground.

[SWAMPHUNTER45]

JAMES to take a stock sbc or bbc and ball hone, re-ring, re-bearing and change flat tappet cam and lifters with a fresh valve job $2,500 is very much do able at smaller machine shops. If within spec there is very little that needs to be bought.

As far as a 383 there are plenty running out there for under 5k maybe not gonna go 10 years but if cared for they make alot of folks happy. A new Whites long block 455hp is 4k, not a Treadwell or MAS but if cared for will get the job done.

http://www.whiteperformance.com/engine_ ... 455hp.html

[StrongVet]

So now I am faced with that age old question: "How fast can you afford to go?" While running dry with 3000 lbs of gear and flesh sounds AWESOME, I'm thinking that I do not necessarily need that on my current build. I probably need to remember that a spade is a spade. What I have is a 35 year old glass hull and some repaired rigging. I know the prop and rudders are going to run $2000 already which will bring this project to $10,000. The big unplanned expense was replacing the engine, but that cannot be avoided. However, dropping another $10,000 on a powerplant and reduction is probably not an investment I will recover anytime soon should I choose to sell and upgrade. Would you pay $20,000 for the boat I just described if it had a new 383 and reduction? Someone might, but could be a long wait.

I'm thinking that I should probably find a used BBC and have it rebuilt to meet my needs. I have a machine shop that found the cracked block and they were going to get it completely rebuilt, bored, and a new cam for around that $2500 mark SWAMPHUNTER45 mentioned. Once I have thrust, then I can get that much-discussed "stick time" everyone talks about, learn what I like and don't like, and then sell, upgrade, and (hopefully) recover some of the expenses I have incurred in this build. And cool as it would be, running dry is probably not going to be much of an issue on the property I hunt due to the canal system they have for rice irrigation and hunting the marsh.

But the next boat. . . .

On the rebuild of the 454, any suggestions? I have seen RV cam and even an entire RV engine. I know I need broad power, especially at the low end. Any experience or suggestions about mods or parts to choose / avoid is appreciated. Again, I'm not a motor guy. I have stroked and bored many things, but never an engine.

[SWAMPHUNTER45]

Check ebay I saw a used 454 out of a truck listed for $800 in Longview Texas!

Worth calling about it and asking questions and try to set up an inspection FYI they are taking offers!!!

[gruprgetr]

first and formost a 35+ year old glass hull referbed haulin 3000k lbs in marsh aint gonna cut it very long before it comes apart with very very bad outcome
paint,slick, and rhino liner do not a solid boat make...............pretty though

[12PSI]

He mentioned in his original post that he replaced the stringers, should be a solid boat for a long time.

[StrongVet]

Safety is primary goal. Entire boat has been gutted down to the bones and replaced as needed. Stringers, transom, glass, etc. Basically a "new" old boat. But if I am missing anything that could be unsafe (my kids will be on this thing), please let me know. I appreciate all the help I can get.

[Deano]

There is NOTHING wrong with a properly restored glass hull.
It looks like you did a really good job to me.

Given a composite prop, you will have addressed the biggest concern.

[StrongVet]

What would you think of this RV motor for a direct drive rig?

496-502 BBC Gen 4, 380 HP, peanut port heads, very mild cam. Stroker 4.310" and 4.350" X 4.250" Steel crank

I can get it for $4000 refurbished and shipped, no rebuild needed (read: save me $2500 or the threat of another cracked block). Again, assume I know next to nothing about engines.

[OneBFC]

I have such a hard time wrapping my head around an automotive engine based DD build when a requirement is a heavy load. It just seems counter productive based on what I know of airboats.

I have seen some automotive DD setups that work well, but always on the lighter side.

If you are staring at $4k for an RV BBC, why not consider a setup like 350-375hp SBC and a used gear box?

Lighter, easy to resell and will result in more thrust.

I mean, why do you want to stick with a DD if you can build a geared setup for same or less?

You DD gurus feel free to set me straight if I am off base. Just have never seen heavy and DD work well.

I think the resell aspect alone would be enough to go with SBC and a box over a 4k DD BBC?

I mean, here is an old article on how to build a 400/400 350 engine:
http://www.hotrod.com/articles/1004clt- ... ine-build/

Anyway, I think you are doing the right thing asking questions and getting input. I sincerely hope you get a setup you are happy with, however you decide to go!

[StrongVet]

The same thought has crossed my mind, although I think it would take more than the $4k. But resale value would be higher if I swapped to SBC with reduction. And SBCs seem easier to find. Since I have all of the rigging out of the boat and can adjust for a few inches of length here or there, would there really be any major changes if I made the switch?

[glades cat]

A 14' x 8', 5 seater is in reduction drive territory. It also addresses any thrust bearing issues related to DD applications. You are so close to building a great boat that responds with authority if you go with reduction.

[Junker]

15 yrs ago I started down the same path your on now.
Picked up a "price was right" hull and rigging, reworked everything, built a trailer, installed a zz4 with a signature prop as a DD.
All in all had 10k into it (the small stuff adds up quick)
It got me out on the water, had some fun but soon realized wanted more performance and peace of mind not getting hung up in places I shouldn't have been to start with..LOL

Soon after, bought a complete gearbox boat, sold the DD for half of what I had in it and have not looked back. Just always looking forward to the next upgrade.

I guess what I'm getting at is if your just "testing the waters" and not sure if airboating is your thing, throw a cheap junk yard RV motor on and go have fun for awhile on the cheap.
Either way you go, DD or gearbox, when you do decide to sell / upgrade your going to lose money....... just depends on how much its going to hurt.

As a side note while you have it disassembled make sure to check your bottom for being true, before putting it all back together to find out you have a bucking bronco.

Have fun .............. and be safe with those kids......