K&B 3.5 Won't Go Around One Time!

[dwb2620]

Pete, That is great news! I'm glad you were able to get some "in-person" help from a fellow boater. Oh yeah, sorry to get off track in your thread. It is just too easy to do that sometimes. Anyway, I hope some of the things I said to check or look for helped you out some.

Happy boating!

David

 

[moparbarn]

Pete, That is great news! I'm glad you were able to get some "in-person" help from a fellow boater. Oh yeah, sorry to get off track in your thread. It is just too easy to do that sometimes. Anyway, I hope some of the things I said to check or look for helped you out some.
Happy boating!

David

ditto for me, sorry about the hijack attempt. i shoulda known you'd call me on it . glad to hear the spitfire is going good now. and you found a third channel transmitter for your airtronics rx's. now, start working on the third channel stuff. oops, there i go, off topic again B) . still happy for ya. later, robin.

 

[Pete Markese]

Pete, That is great news! I'm glad you were able to get some "in-person" help from a fellow boater. Oh yeah, sorry to get off track in your thread. It is just too easy to do that sometimes. Anyway, I hope some of the things I said to check or look for helped you out some.
Happy boating!

David

David, without question your input was a BIG help. Thank you for that. This is still a work in progress. The Spitfire is now on plane and running semi-strongly, BUT you know how it goes...we're now looking for more speed, and we know the boat is capable of it. Are these things ever done? I don't think so. That's the hobby. Right? Again, thank you for all of your help.

 

[Pete Markese]

looks way to deep to me.. Its hard to tell from the pics but I would say the motor has to go up 1/4" (5mm)
grimracer

Pete,

I agree with Grimracer. I would raise the motor up another 1/8 to 1/4 of an inch higher. I would even try another 1/16 to 1/8 higher than previously mentioned. The highest I would go is having the bottom of the prop shaft even with the bottom of the rear sponsons. There is no reason to go higher as that just would be overkill.

******Disclaimer: It's been about 10 years since I have ran this boat****** On my boat what I did was cut a 1/8 step on the center sponson for about 2 inches long. It seemed to settle the rear of the boat down and change the AOA of the front sponsons. So, basically it lowered the rear of the boat 1/8 of an inch. I think I still have the hull sitting up in the garage attic. If I do, I'll try to get a pick of the center sponson mod that I did. I only did this because I didn't like how high the rear of the boat was riding out of the water when on plane.

I also noticed on your engine it seems that the intake isn't radiused for a venturi effect. It's hard to tell in the pic. That might be affecting the fuel draw. On my engine, I ran the Prather exhaust throttle with a Irwin o/b pipe. All of my engines were modded by me. Mainly just a little port matching and raise the exhaust a little. Nothing major or trick.

Hope this helps,

David

David, cutting the center ride plate is interesting. You say that doing that got the rear of the boat to settle down a little. With my Spitfire, the boat is on plane, but it's still riding way too wet on the rear and not getting up on the front sponsons as much as we'd like to see it. We're thinking that the CG is too far toward the stern of the boat, and we're trying to think of how to move it more forward toward the bow. I actually just added a piece of 1/16" plywood to the center ride plate, as we thought that it needed to be extended to help get the rear of the boat up. Any thoughts on how to get the boat more up on the front sponsons?

Also...do you have any pics showing how you radiused the intake? I've never done that, but it makes a lot of sense to me to do it. I don't want to screw things up, so anything you can offer to help me better understand how to do that would be great. Thanks.

 

[dwb2620]

looks way to deep to me.. Its hard to tell from the pics but I would say the motor has to go up 1/4" (5mm)
grimracer

Pete,

I agree with Grimracer. I would raise the motor up another 1/8 to 1/4 of an inch higher. I would even try another 1/16 to 1/8 higher than previously mentioned. The highest I would go is having the bottom of the prop shaft even with the bottom of the rear sponsons. There is no reason to go higher as that just would be overkill.

******Disclaimer: It's been about 10 years since I have ran this boat****** On my boat what I did was cut a 1/8 step on the center sponson for about 2 inches long. It seemed to settle the rear of the boat down and change the AOA of the front sponsons. So, basically it lowered the rear of the boat 1/8 of an inch. I think I still have the hull sitting up in the garage attic. If I do, I'll try to get a pick of the center sponson mod that I did. I only did this because I didn't like how high the rear of the boat was riding out of the water when on plane.

I also noticed on your engine it seems that the intake isn't radiused for a venturi effect. It's hard to tell in the pic. That might be affecting the fuel draw. On my engine, I ran the Prather exhaust throttle with a Irwin o/b pipe. All of my engines were modded by me. Mainly just a little port matching and raise the exhaust a little. Nothing major or trick.

Hope this helps,

David

David, cutting the center ride plate is interesting. You say that doing that got the rear of the boat to settle down a little. With my Spitfire, the boat is on plane, but it's still riding way too wet on the rear and not getting up on the front sponsons as much as we'd like to see it. We're thinking that the CG is too far toward the stern of the boat, and we're trying to think of how to move it more forward toward the bow. I actually just added a piece of 1/16" plywood to the center ride plate, as we thought that it needed to be extended to help get the rear of the boat up. Any thoughts on how to get the boat more up on the front sponsons?

Also...do you have any pics showing how you radiused the intake? I've never done that, but it makes a lot of sense to me to do it. I don't want to screw things up, so anything you can offer to help me better understand how to do that would be great. Thanks.

Pete,

Cutting the center ride plate is NOT something I would recommend if your boat is riding wet in the rear. The cutting of the ride plate would only make it run wetter back there as it would lower the rear of the boat. I does sound like your CG is too far back.

I would be glad to take some pictures for you of the radius on the intake. The procedure of radiussing the intake is actually pretty simple to do with a dremel. I just stuffed some tissue down into the intake and started cutting away with my dremel. Just have to make sure the bits of aluminum don't get into the engine. The best way to make sure that doesn't happen is to take the top housing off and dis-assemble it. Then do your cutting away from your workbench from where your engine is torn apart.

Every day when I am at work I think about pulling all of that stuff out. Then I get home and FORGET. I guess I need to write a note to myself on my forehead or something so I'll remember. :lol:

Give me a few days and I'll get to that over the weekend when I have some time. I'll also pull the old hull down out of the attic and see how I had everything mounted so I give you an idea of what my CG was.

Later,

David

 

[Pete Markese]

looks way to deep to me.. Its hard to tell from the pics but I would say the motor has to go up 1/4" (5mm)
grimracer

Pete,

I agree with Grimracer. I would raise the motor up another 1/8 to 1/4 of an inch higher. I would even try another 1/16 to 1/8 higher than previously mentioned. The highest I would go is having the bottom of the prop shaft even with the bottom of the rear sponsons. There is no reason to go higher as that just would be overkill.

******Disclaimer: It's been about 10 years since I have ran this boat****** On my boat what I did was cut a 1/8 step on the center sponson for about 2 inches long. It seemed to settle the rear of the boat down and change the AOA of the front sponsons. So, basically it lowered the rear of the boat 1/8 of an inch. I think I still have the hull sitting up in the garage attic. If I do, I'll try to get a pick of the center sponson mod that I did. I only did this because I didn't like how high the rear of the boat was riding out of the water when on plane.

I also noticed on your engine it seems that the intake isn't radiused for a venturi effect. It's hard to tell in the pic. That might be affecting the fuel draw. On my engine, I ran the Prather exhaust throttle with a Irwin o/b pipe. All of my engines were modded by me. Mainly just a little port matching and raise the exhaust a little. Nothing major or trick.

Hope this helps,

David

David, cutting the center ride plate is interesting. You say that doing that got the rear of the boat to settle down a little. With my Spitfire, the boat is on plane, but it's still riding way too wet on the rear and not getting up on the front sponsons as much as we'd like to see it. We're thinking that the CG is too far toward the stern of the boat, and we're trying to think of how to move it more forward toward the bow. I actually just added a piece of 1/16" plywood to the center ride plate, as we thought that it needed to be extended to help get the rear of the boat up. Any thoughts on how to get the boat more up on the front sponsons?

Also...do you have any pics showing how you radiused the intake? I've never done that, but it makes a lot of sense to me to do it. I don't want to screw things up, so anything you can offer to help me better understand how to do that would be great. Thanks.

Pete,

Cutting the center ride plate is NOT something I would recommend if your boat is riding wet in the rear. The cutting of the ride plate would only make it run wetter back there as it would lower the rear of the boat. I does sound like your CG is too far back.

I would be glad to take some pictures for you of the radius on the intake. The procedure of radiussing the intake is actually pretty simple to do with a dremel. I just stuffed some tissue down into the intake and started cutting away with my dremel. Just have to make sure the bits of aluminum don't get into the engine. The best way to make sure that doesn't happen is to take the top housing off and dis-assemble it. Then do your cutting away from your workbench from where your engine is torn apart.

Every day when I am at work I think about pulling all of that stuff out. Then I get home and FORGET. I guess I need to write a note to myself on my forehead or something so I'll remember. :lol:

Give me a few days and I'll get to that over the weekend when I have some time. I'll also pull the old hull down out of the attic and see how I had everything mounted so I give you an idea of what my CG was.

Later,

David

David, that would be great if you send some pics, and I totally understand the getting home from work and forgetting to do this stuff. That's one of the reasons why I love this hobby, I go into the garage and everything else but the boat in front of me disappears from my mind! Hey on cutting the center ride plate...I didn't cut it...I added a 1/16th piece of plywood to it's depth. In other words I made it bigger so it would provide more lift, at least, that's what we hope it will do. I pretty knowledgeable boater suggested this. He's designed and built boats and is quyite well versed on hydros (outriggers) and tunnels. I couldn't dispute his advice, so I did it. If the boat sinks the next time out, I'm going to retrieve it and then throw it at him, or maybe just ask him to take his to his house and fix it once and for all! Anyway, thanks again. I truly appreciate any help you can give me.

 

[moparbarn]

to radius the intake, do what david explained. think of a trumpet or trombone bell shape. that's what the inside of the intake should look like. from just shy of the outer edge at the top, funneling down to the intake slot at the crankshaft. nice and round and curved and smooth. take all the steps out of there. just be very careful at the bottom, don't hit the crank or change the shape of the intake slot. the intake slot is the opening at the bottom of the intake passage/hole/ex-carb mount that feeds the intake port in the crankshaft. that would change the amount and timing of the intake charge. not port timing, that is in the sleeve. there may be beneficial mods in that area. but, not knowing about that, i would leave it untouched. you can work everything leading down to it. just leave the slot at the bottom alone. take out the needle and fuel nipple, before starting, and reinstall the fuel nipple flush with the new contour. hope this helps you.

 

[dwb2620]

to radius the intake, do what david explained. think of a trumpet or trombone bell shape. that's what the inside of the intake should look like. from just shy of the outer edge at the top, funneling down to the intake slot at the crankshaft. nice and round and curved and smooth. take all the steps out of there. just be very careful at the bottom, don't hit the crank or change the shape of the intake slot. the intake slot is the opening at the bottom of the intake passage/hole/ex-carb mount that feeds the intake port in the crankshaft. that would change the amount and timing of the intake charge. not port timing, that is in the sleeve. there may be beneficial mods in that area. but, not knowing about that, i would leave it untouched. you can work everything leading down to it. just leave the slot at the bottom alone. take out the needle and fuel nipple, before starting, and reinstall the fuel nipple flush with the new contour. hope this helps you.

Yeah, like moparbarn said! Sorry about not describing it in more detail. Yes, leave the bottom of the intake next to the crankshaft ALONE!

David

 

[dwb2620]

Here is a link to some pictures of my old Spitfire O/B. Just a word of warning, when I pulled the old boat out, That's when I remembered "what I did with it". I sort of "retired the boat". The pictures are self explanatory! h34r: h34r: h34r:

Just a little TLC and it "could" be as good as new.

http://www.intlwaters.com/index.php?automo...m&album=201

David

 

[Pete Markese]

David, I'm not sure why...BUT...I cannot get to the pics file. Whe3n I click on that link, I get an error message telling me that I do not have permission to use that feature. I'm not sure what that means.

Anyway, I'd love to see the pics. Can you send them to my email address at [email protected]? If so, please do.

I'm still a little apprehensive about ripping away at that intake with my dremel. Hope fully you know how it goes, when

you've never done it before, it's always a little scary. Some pics of an intake that has been radiused would be a great help.

 

[dwb2620]

David, I'm not sure why...BUT...I cannot get to the pics file. Whe3n I click on that link, I get an error message telling me that I do not have permission to use that feature. I'm not sure what that means.
Anyway, I'd love to see the pics. Can you send them to my email address at [email protected]? If so, please do.

I'm still a little apprehensive about ripping away at that intake with my dremel. Hope fully you know how it goes, when

you've never done it before, it's always a little scary. Some pics of an intake that has been radiused would be a great help.

Yes, I fully understand about cutting away with a dremel. One slip and "oops!' , you've permanently damaged a part.

I'll do my best to get those pics to your e-mail address.

Later,

David