Project Prather

[Doubledog]

Howdy, new guy to most, but a lot of you will know me from other sites. Gave up nitro 15 or so years ago due to career change and have picked up gas boats the last two years.

Recently however, I acquired an older Prather A' boat w/ K&B 3.5 exhaust throttle engine. Just looking to stay entertained a little is all.

Here's what I've got.

View attachment 487

 

[Doubledog]

Old.

Subsurface setup.

View attachment 488

 

[Doubledog]

Looking to upgrade to a surface drive.

Can this be done epoxing & glassing the stuffing tube inside the hull ? Seems like it shouldn't be a problem.

View attachment 489

 

[Doubledog]

Heavy

I'd like to get rid of the wood rails and glass aluminum in. Whats the opinions on this?

View attachment 490

 

[Doubledog]

engine

The gentleman that sold it I'm really wanting to trust. He said the boat was almost (over) 10 years old and hadn't been ran in 5 or so years with not that much run time on it. It looks to be in good shape anyhow. We'll see more when it gets torn down.

I'm not crazy about jumping back into nitro with an exhaust throttle engine. Prefereably something easier to use.

Any opinions on thes engines? Besides being a pain?

No racing, just play. Something to keep me interested.

View attachment 491

 

[snowdog-2112]

Doubledog,

Exhaust throttles are not popular for whatever reason, I can't remember why as I've never experienced them. OBNut uses them and really likes them. Contact him through IM and see what he has to say.

Snowdog

Snowdog racing: Sharing the wealth.

 

[Doubledog]

Thanks for the help.

I'm hoping he'll pass by the thread and shead some light. The guy that sold me the rig said those types of engines don't like to idle but likes to be more in the mid to upper throttle setting.

Here's the engine after a little cleaning. Looks to be in real good shape after a quick tear down.

View attachment 493

 

[rhomodel]

I would keep the rails, just clean it up. Before buying a new engine first try this one, may be it's not so bad after all, you can always get yourself a new engine Jaimy. As for the surface drive, just remove the submerged one and fill the hole and drill a new hole in the transome. I think you even do not have to get yourseld a new strut, just a new stuffing tube and cable.

Julius

 

[Doubledog]

Hey Julius ! Good to hear from you brother.

I'm thinking the strut will be fine also it'll just need more setback.

This engine has me shaking in my boots for some reason. I guess due to the fact that its something new to me.

Btw, A regular 3.5 carb (k& B) should work with this so it can be changed to work like normal? IF so, somebody hook me up.

 

[Don Templeton]

I wouldn't worry about the exhaust throttle and venturi set up at all. If the engine and bearings are OK,I think you'll find it easier to tune than with a carb. I ran this set up for years and never had any problems.

Don

 

[Doubledog]

Thank you for the encouragement.

 

[MarkScott]

DD,

As Snowdog points out, I use Throttle Exhaust on my K&B outboards. LOVE THEM ;D The setup you have should work wonders.. When you do get the surface drive put in, I'm certain you have a grin from ear to ear! If you want to try carb's instead, let me know.. Got plenty of the stock black carbs and one that's been drilled out to red(?) specs..

Mark

OB Nut Racing: What's idle??? All I know is WFO...

 

[rhomodel]

As an added bonus, the strut it comes with does give some free space for the prop to be in calmer water, instead of right behind the transom. Don't ask me what prop would be good as a G-20 is a tad too big for a .21

 

[Doubledog]

WOW !

Can't thank you guys enough. My shoulders feel lighter already

Julius, haven't really had time to test the pipe and G20 yet. Been to run a couple times but there was either too many swimers in the water or boats or something. Still need to get the pipe dailed in and then it'll be fun!

Have a good one,

 

[Propjockey]

DD...are ya having fun yet?! ;D

I agree with everyone else so far...that particular exhaust throttle is one of the better ones, and you'll be quite pleased with it after it's running.

On the rails...leave 'em in. I don't think it will be worth all the effort of reconstructive surgery for the minimal weight savings. (Gee...sounds like I'm speaking from experience... )

If you go surface drive, get (or make) a bracket to move the strut away from the transom a couple of inches so you will have a bit of adjustment on the prop depth.

And something to put in the back of your head...auto-bailers. Side draft intakes are prone to sucking up water in the hull...may not be the case here, but something to look for once it's running.

Good luck, Dude. Keep us informed.

 

[Doubledog]

Hey man, I'm having a ball ! ;D

You guys have really came to the rescue with ideas in just a short time.

Last questions for about a week or so till I can get some of this stuff done:

Question: What size of the brass stuffing tube? I'm in Europe so going to the local HomeDepot and buying it will mean METRIC.

Also, do you just lube down your shaft ;D real good or do you prefere to go a size or two larger and use teflon insert? If so, where do I buy the teflon?

Lots of questions and lots of good answers. Hope to pass the knowledge.

 

[wswatzell]

Don’t know about getting them shipped over seas, but Aeromarine has the Teflon tubes. Here is the link

http://www.aeromarinerc.com/

 

[Ron Olson]

Aeromarine parts are sold in Europe by JoTiKa Ltd. in England, www.jotika-ltd.com .

 

[[email protected]]

DD,

I've had several of those K&B motors and they always performed well. For smaller motors they really tend to gulp up the fuel and are a bit messier. Bit hey, more mess equals more fun, right??

I'd also suggest that on the barrel of the exhaust throttle you make two marks with a scrib. One is for Full Open, the second is for Full Closed. Remeber that once the pipe is on the motor you won't be able to see if your full open like you can if you were looking inside of a carburetor.

 

[Don Templeton]

"Yup"

I make all my throttle adjustments before the pipe goes on!