K/b RED CARB SETTING 3.5CC

[Jcazz]

where does the needle need to be on RED k/B Carb 3.5CC header and pipe....THX!

 

[Jcazz]

where does the needle need to be on RED k/B Carb 3.5CC header and pipe....THX!

Reason i ask is someone once said that it was a 7.5CC carb? anyways i know its the last carb k/b made with different color... all shiny red, any answers????? where the needle needs to be set at

 

[SayMikey]

where does the needle need to be on RED k/B Carb 3.5CC header and pipe....THX!

Reason i ask is someone once said that it was a 7.5CC carb? anyways i know its the last carb k/b made with different color... all shiny red, any answers????? where the needle needs to be set at

Gold was last red is big for a 20 motor good luck

 

[HTV Boats]

The red is a .343 bore version and too big for a .21. The stock black is .265 and many got bored out over the years to .281 or .312 which coinsidentally are a 9/32 and 5/16 drill bit. Rod the carb master G would tell you .290 is all you need on a 3.5. The Gold carb is a factory .312 meant for the 3.5. Red was targeted for a 7.5 and a few guys who want overkill and less performance on a 3.5. Kind of like putting a 1000 CFM carb on your 283 Chevy. Go with the smaller bore and spend time on props and set up before you try to make mega HP. (boy I should listen to my own advice more often)

In most K&B needle in carbs I started at 4 turns and wound up betwwen 3 1/4 to 3 3/4 on the 3.5's I have run over the years. Can be affected by pipe pressure anf location of the tank also.

 

[moparbarn]

The red is a .343 bore version and too big for a .21. The stock black is .265 and many got bored out over the years to .281 or .312 which coinsidentally are a 9/32 and 5/16 drill bit. Rod the carb master G would tell you .290 is all you need on a 3.5. The Gold carb is a factory .312 meant for the 3.5. Red was targeted for a 7.5 and a few guys who want overkill and less performance on a 3.5. Kind of like putting a 1000 CFM carb on your 283 Chevy. Go with the smaller bore and spend time on props and set up before you try to make mega HP. (boy I should listen to my own advice more often)In most K&B needle in carbs I started at 4 turns and wound up betwwen 3 1/4 to 3 3/4 on the 3.5's I have run over the years. Can be affected by pipe pressure anf location of the tank also.

all excellent info, mic. agree with everything you say, except red carb on a 3.5 . yes, it was intended for the 7.5, but it can work well on a 3.5 drum rotor i/b . i know that it's not an ob, but hadda throw it in here.

 

[NAMBA860]

the red carb is pretty old it was intended for the disk rotor 7.5 inboard there was also a purple which was the same except the color. i have tried them all i like the gold it seems to be just right.

 

[Jcazz]

Funny you all say this, But when my boat was not piped and ran red carb, I was able to pass a freind up with his piped K/b with gold carb I have never seen a slow down with my engine and the red carb/ Gold.....The only complaint i have is the barrel screw likes to come loose now and then, which gets annoying

 

[NAMBA860]

Funny you all say this, But when my boat was not piped and ran red carb, I was able to pass a freind up with his piped K/b with gold carb I have never seen a slow down with my engine and the red carb/ Gold.....The only complaint i have is the barrel screw likes to come loose now and then, which gets annoying

i actually run joe monohans exhaust throttle on my 3.5 with a k/b venturi i really like that set up

 

[sneakysneakyracing]

Funny you all say this, But when my boat was not piped and ran red carb, I was able to pass a freind up with his piped K/b with gold carb I have never seen a slow down with my engine and the red carb/ Gold.....The only complaint i have is the barrel screw likes to come loose now and then, which gets annoying

i actually run joe monohans exhaust throttle on my 3.5 with a k/b venturi i really like that set up

There are other alternatives.

3 and 1/2 turns from closed is a good starting point. get yourself a (garmin forerunner 101 gps) 50gm in weight and about $80 on ebay. drop it in your radio box and tune your boat for the fastest speed.

bloging is not the only way.

regards,

 

[Jcazz]

Thank you for everyones help.

 

[TUNLBOTR]

The red is a .343 bore version and too big for a .21. The stock black is .265 and many got bored out over the years to .281 or .312 which coinsidentally are a 9/32 and 5/16 drill bit. Rod the carb master G would tell you .290 is all you need on a 3.5. The Gold carb is a factory .312 meant for the 3.5. Red was targeted for a 7.5 and a few guys who want overkill and less performance on a 3.5. Kind of like putting a 1000 CFM carb on your 283 Chevy. Go with the smaller bore and spend time on props and set up before you try to make mega HP. (boy I should listen to my own advice more often)In most K&B needle in carbs I started at 4 turns and wound up betwwen 3 1/4 to 3 3/4 on the 3.5's I have run over the years. Can be affected by pipe pressure anf location of the tank also.

Mic

O contrare', .343 Is EXACTLY right for .21, NOVA sends .350 with motors, and .343 is what holds IMPBA 2 lap oval world record, and is widely used on mod 21's, Is carb used by Otto, Drake, Whiddon, and myself. I believe Hearl runs the .350 Nova carb on his. It ain't overkill. It just don't work for u..............

Randy

 

[Jcazz]

 

[HTV Boats]

The red is a .343 bore version and too big for a .21. The stock black is .265 and many got bored out over the years to .281 or .312 which coinsidentally are a 9/32 and 5/16 drill bit. Rod the carb master G would tell you .290 is all you need on a 3.5. The Gold carb is a factory .312 meant for the 3.5. Red was targeted for a 7.5 and a few guys who want overkill and less performance on a 3.5. Kind of like putting a 1000 CFM carb on your 283 Chevy. Go with the smaller bore and spend time on props and set up before you try to make mega HP. (boy I should listen to my own advice more often)In most K&B needle in carbs I started at 4 turns and wound up betwwen 3 1/4 to 3 3/4 on the 3.5's I have run over the years. Can be affected by pipe pressure anf location of the tank also.

Mic

O contrare', .343 Is EXACTLY right for .21, NOVA sends .350 with motors, and .343 is what holds IMPBA 2 lap oval world record, and is widely used on mod 21's, Is carb used by Otto, Drake, Whiddon, and myself. I believe Hearl runs the .350 Nova carb on his. It ain't overkill. It just don't work for u..............

Randy

Randy,

Cannot argue with success of the boaters you mentioned with larger carb bores but not sure what carbs are they using and that the spray bars are equal in all applications. Don't think these are K&B red carbs. And you're correct has not worked for me in .21's I think the original thread was for average boaters which I honestly feel will struggle more with bigger carbs.

Just for a thought take a .343 bore and you get .0924 sq in area. Subtract the volume of a full .090? bar across the carb and your down .0308 sq in and a real cross sectional area of .0616

now take a .312 bore and empty you get .0764 sq in area. if it has a K&B style spray nipple at .090 going one third of the way across the bore you subtact .090 X.312 X .333 or .0093. .0764 minus .0093 leaves a .0761 sq in area considerably larger than the .343 with a full spray bar. All I am saying here is the real flow volume is effected by the size of the spray bar.

The red carb being .343 with only a spray nipple comes out around .0816 volume. The range here is between .0616 and .0816 all things considered. When it comes to carbs you really need a flow bench. Geraghty might know what they all really flow.

 

[moparbarn]

randy, i think most of what has been said about the red carb not working has been meant on a k&b .21. that's what i was referring to. the original question doesn't state engine make, just 3.5 cc with pipe. so we can only guess what engine & pipe combo we're talking about..................... my personal favorite on a 3.5 k&b is a black carb opened up to about .297" - .300" with a 30 degree spray bar. it seems to pull better thru the turns & not give up enough to notice in the straights. never "falls off", second stages sooner, too .

 

[TUNLBOTR]

randy, i think most of what has been said about the red carb not working has been meant on a k&b .21. that's what i was referring to. the original question doesn't state engine make, just 3.5 cc with pipe. so we can only guess what engine & pipe combo we're talking about..................... my personal favorite on a 3.5 k&b is a black carb opened up to about .297" - .300" with a 30 degree spray bar. it seems to pull better thru the turns & not give up enough to notice in the straights. never "falls off", second stages sooner, too .

\

Robin

Yeah, Mic is right concerning the carb choices, as far as KB's go motors are less likely to pull 343 out of the box, combinations of pipe, prop, mods on motor, etc... all play in. But I am 1994 and 1995 IMPBA dist 3 high points champion, back when DIII was FL GA SC , and the combination was KB motor, red carb, x440 prop, 55% Otto fuel and an EQUI pipe, stinger cut off 3/8 inch. And you have had success with Equi Pipes, If I remember the right boat. Nova is apples and oranges. Have used Rod G's carbs with much success on Nova and CMB TT in the past, and they are tiny compared to where we are now (they were 285 290).

But I didnt swallow an engineering degree like Mic, So I can't rattle off Volumetric Efficiency and CFM's. All I can do is knock the hell out of 60 MPH with my current setup, and GOOD LORD willing and the creek don't rise, do it over and over.

Its called walking the walk, cause I can't do nuttin else.................

RP

 

[moparbarn]

you're right, randy, i do like the equi 'S' pipe. i don't shorten the stinger, but do reduce it. out of all my pipes, the equi is the easiest to set up & the most "driveable". the power is comparable to any of my other pipes, also. the x-440 is my basic starting point for prop choices, & usually where i end up...........although the x-442 (heavily modded/reduced) & x-637 are giving good results. the x series seem easier to drive & set up than 1440's, for me. my black carbs were modded by james at OER, he said he learned it from rod gerahty.

 

[HTV Boats]

I never did finish engineering school as I got transferred to University of Da Nang, Monkey Mountan campus. And while Randy's kicking our butts in stock 20 at Brandon in a couple weeks, I will have to refresh his history on who was winning heats at the Internats in FT Worth in 94. In reality some fun poking sticks here but Randy does know now to make .21's run and one of the few around who will help you make yours better. Now if he'd just bring out a .45 to play. As for Robin nothing but respect as he is a K&B guru.

Mic

 

[moparbarn]

a guru ???? pretty strong words to describe some old hippie out in his garage with a die grinder :lol: :lol: . i do appreciate the compliment, mic ! but when you just mess with 1 style of hull, & 1 make & size of engine, it makes it a LITTLE easier . looking foward to seeing you & randy in charleston again, next spring !!!

 

[topfuel443]

meh.... Randy's a chump.

A little 6 month advancement on smack talk never hurt anyone.

~James

 

[TUNLBOTR]

meh.... Randy's a chump.
A little 6 month advancement on smack talk never hurt anyone.

~James

Gabe

Now that the olympics are over, let the REAL games begin.

Hope you build sumtin' faster than what you been runnin, soze I can wear you out with these 4 year old Vans Racing weapons of ARS destruction.Last year I played the silent game. This year, I'll just bring the PAIN.

Sincerely,

THE GAME...............

P.S. MOB RULES.................

P.S.S. come on Poole, you know you want some too!!!!!!!!