IMPBA Sport O/B Tunnel Rules

[Tunnelbill]

Sport Outboard Tunnel Rules

Engine and Hull Specifications

1. There shall be one engine class, Class B.

2. The Sport outboard class shall use tunnel boats only.

3. The Sport outboard tunnel class shall not lock down the engine or use any

auxiliary steering system.

4. Original carb bore and exhaust configuration will be retained as

manufactured. No modification to the carb bore or exhaust outlets will be

allowed.

5. No high performance exhaust systems (tuned pipes) will be allowed, even if

they are offered by the manufacturer of the engine. Clarification: the two

outlet exhaust / muffler chambers offered by K&B and O.S. are not

considered tuned pipes and will be allowed in the Sport outboard tunnel class.

Engine Specifications

1. Engines must be standard factory production with a minimum of 100 units

available for sale to the general public. To be eligible for the International

Regatta the engines must have been offered for sale to the general public not

less than ninety (90) days prior to that year's International Regatta.

2. The powerhead and lower unit must be of the same manufacturer and model.

3. The engine external parts shall remain as originally manufactured within

series except as shown in Part 4. Clarification: No water-cooled engine parts

shall be used with air-cooled engine parts. Common engine parts that are used

on both engines models may be interchanged. Slide valve exhaust adapters

may not be used with carburetor equipped engines.

4. The following exceptions will be allowed in the Sport Outboard Tunnel

specifications.

a. Adhesives (loctite), set screws and jam nuts.

b. Any carb linkage arms.

c. Any motor mount.

d. Any glow plug, fuel brand and mixture.

e. Any type steering arm.

f. Any flywheel nut.

g. The lower unit below the cavitation plate may be trimmed, sharpened

or polished. No material shall be added to the lower unit.

h. Adjustable mixture controls will be allowed, however the original

needle valve must remain in its original position.

Sport tunnel engine inspection procedures

The maximum carb bore and exhaust outlet bore size shall not exceed 0.320 inches. These

may be checked with a 'GO, NO-GO' gage or dial calipers. Note: It will be the contestant’s

responsibility to check and verify carb bore and exhaust outlet bores prior to the contest. Any

infraction concerning the carb or exhaust bore sizes will result in immediate disqualification

from the contest.

Can I put a arm on the stock needle to adjust the fuel? As I read the rules I can, see 4, b and 4, h. :blink:

Thanks,

MTB

 

[topfuel443]

I dont see any reason why not. When it mentions the "carb linkage" most would assume the throttle arm/connector for arm. But it doesnt say that specifically. As long as you use an original needle assembly as noted, there is nothing else that says you cant.

Good idea Bill, ~ James

 

[Tunnelbill]

I dont see any reason why not. When it mentions the "carb linkage" most would assume the throttle arm/connector for arm. But it doesnt say that specifically. As long as you use an original needle assembly as noted, there is nothing else that says you cant.

Good idea Bill, ~ James

James,

Thanks, I want to put a remote needle on my Lynx/OS. Most of the needles I have are to big, OS/Base needles. I do not have very much room in the back for a needle so I'm going to make the main needle ajustable.

Thanks,

MTB

 

[PhillyDees]

I dont see any reason why not. When it mentions the "carb linkage" most would assume the throttle arm/connector for arm. But it doesnt say that specifically. As long as you use an original needle assembly as noted, there is nothing else that says you cant.

Good idea Bill, ~ James

James,

Thanks, I want to put a remote needle on my Lynx/OS. Most of the needles I have are to big, OS/Base needles. I do not have very much room in the back for a needle so I'm going to make the main needle ajustable.

Thanks,

MTB

Yall aren't running a 45 class? I just bought a 45 setup so I could run impba. I live in ky and am ready to race mod D Class. Can it happen in 2010 a 45 class

 

[SayMikey]

I dont see any reason why not. When it mentions the "carb linkage" most would assume the throttle arm/connector for arm. But it doesnt say that specifically. As long as you use an original needle assembly as noted, there is nothing else that says you cant.

Good idea Bill, ~ James

James,

Thanks, I want to put a remote needle on my Lynx/OS. Most of the needles I have are to big, OS/Base needles. I do not have very much room in the back for a needle so I'm going to make the main needle ajustable.

Thanks,

MTB

Yall aren't running a 45 class? I just bought a 45 setup so I could run impba. I live in ky and am ready to race mod D Class. Can it happen in 2010 a 45 class

Where are you in Ky ? We run d mod in Evansville Im

 

[PhillyDees]

I dont see any reason why not. When it mentions the "carb linkage" most would assume the throttle arm/connector for arm. But it doesnt say that specifically. As long as you use an original needle assembly as noted, there is nothing else that says you cant.

Good idea Bill, ~ James

James,

Thanks, I want to put a remote needle on my Lynx/OS. Most of the needles I have are to big, OS/Base needles. I do not have very much room in the back for a needle so I'm going to make the main needle ajustable.

Thanks,

MTB

Yall aren't running a 45 class? I just bought a 45 setup so I could run impba. I live in ky and am ready to race mod D Class. Can it happen in 2010 a 45 class

Where are you in Ky ? We run d mod in Evansville Im

Louisville

 

[MarkScott]

We have raced D mod at the Cindy race in years past.. The Wine Race does not run D tunnel though...

 

[PhillyDees]

We have raced D mod at the Cindy race in years past.. The Wine Race does not run D tunnel though...

They need to run d mod at the wine run because that is the closest race to me. Will yall see if that can happen this year.

 

[maddog]

They probably would if they have enough entries to make a class but Chris Jenkins is the one to ask that question of he goes by Chriscrash on here and also has something to do with "FAIRY DUST"

 

[MarkScott]

Jul and I would show up with out D tunnels. With PhillyDees, that makes 3! Come on Chris!

Sorry Bill for hi-jacking the thread. Nice idea however.. Just picked up a Cobra. Currently wondering how to stuff a 3rd channel remote in this boat. Put some pics in here with your idea if you so desire to share...

 

[topfuel443]

Im actually in the process of stealing Bills idea right now.. should work pretty sweet! Its a fairly easy thing to do. I run an OS on my sport, and a OS carb on my mod, so it will be on both of em. I am just making an arm on the mill that slides onto the stock needle, it has a set screw to tighten down on the needle.

~James

 

[Tim_Duggan]

I am just making an arm on the mill that slides onto the stock needle, it has a set screw to tighten down on the needle.

~James

From memory OS already have such a thing - it used to come with the 81VRM engine. Found it. Link

 

[Kris Flynn]

hey, I have one of those Tim

 

[topfuel443]

Tim/Kris, do they fit properly on the stock XM needle?

~James

 

[PhillyDees]

We need a .45 class close and the only way to do that is we can get all of yall my racing friends to come and race with me. .45 class is a ball beauce they are fast. not rigger fast but real life tunnel fast.

 

[maddog]

Hey PhillyDees were in Kentucky are you?

 

[SayMikey]

Post 6 he is in your back yard Louisville like 30 minutes away

 

[maddog]

Hey Philly have you ran at Hubers Winery before?

 

[Tim_Duggan]

Tim/Kris, do they fit properly on the stock XM needle?

~James

James,

I'll try to find it and check it on the XM for you. I might still have it tucked away somewhere....

 

[Kris Flynn]

I will let you know tomorrow...From memory the bore was a little big for the needle, but I will confirm this.