Carb Problems

[Bandit64]

Dan it looks great, what type of carb do you have there? Looks like your using the same intake tubes, do you think with that carb all 4 cylinders will get the same amount of fuel and you wont have an issue with half of the cylinders running either lean or rich? What made you decide to go with that carb? And the big question do you think you will have an increase in HP?
Thanks
Nick

Hey nick, for now I'm using the stock tubes. I may order some pre bent ones and weld them up so I have a streight path to the cylinders at a later date. The carb is a minkuni 42 mm at chucks recommendation. He thinks it will give it 20 more hp. I could only hope. As far as lean rich at the cylinders, I don't have a clue. I don't know what to do if its not balanced. I hope to get some input on that.
Like I said, I'm so frustrated with this whole issue that I'm willing to try anything. I can't get any help with it.
My intake is a complete guess. With no real direction. If someone could direst me, I can build anything. ( like, make the rear cylinder tubes longer then the frot ones) ???
I just hope I don't damage my engine! I wish I wasn't the ginni pig. It just doesn't seem like there is much interest in the situation.
Thanks, dan

[eskimoboy]

Dan im glad someones taking the bull by the horn, if there is something that I can do to help just ask. I hope it all works out fine. Dan do you know whats the difference between your mikuni and Buzzbaits mikuni because they dont look the same. The type Buzzbait is using looks like the same carbs on our Bombardier snowmobiles.
Nick

[Bandit64]

Dan im glad someones taking the bull by the horn, if there is something that I can do to help just ask. I hope it all works out fine. Dan do you know whats the difference between your mikuni and Buzzbaits mikuni because they dont look the same. The type Buzzbait is using looks like the same carbs on our Bombardier snowmobiles.
Nick

Mine is a flat slide and his is a round slide. Both mikuni. Mine is used a lot on Harley motorcycles.

[Bandit64]

Looks great! Maybe you should be selling manifolds. I found a larger airfilter worked significently better for me. I'm going to try something a little different, a carb on top of the manifold.

If I could have got a Holley at a reasonable price I would have gone that rout because building an intake for the bottom of a carb would have been easier.

[eskimoboy]

Dan theres a bunch of holley carbs on ebay what type were u looking for?

[Bandit64]

Dan theres a bunch of holley carbs on ebay what type were u looking for?

I was told to use the center carb that goes with the tri carb set up. I did some research and have the part number but I wasn't able to find one reasonable. Best I saw was used for 300. Really used.
Besides that, I was told that you have to change this and that before it will work. I had no idea what he was talking about so when he ( chuck) mentioned mikuni I decided to go with that one.
So for now I'm gonna try this set up. Thanks though.
If you try it and it works better then ill switch.
It's kinda like me using my stock tubes, I don't want to spend a bunch of money on something that's not proven.
Thanks, dan

[eskimoboy]

I looked at Chucks New carb set-up post and he mentions a holley 350 cfm carb I think in 2 barrel and there are some of them on ebay. How would the Holley carb be different than the Mukinis performance wise?

[Bandit64]

I looked at Chucks New carb set-up post and he mentions a holley 350 cfm carb I think in 2 barrel and there are some of them on ebay. How would the Holley carb be different than the Mukinis performance wise?

That's the one. If found a good price maybe I was just unlucky when I was looking. Chuck seems to think the mikuni I have will work just as good. That is, both carbs we are talking about with the proper intake.
Thats the snag. I haven't seen one. Intake that is. If I could see one ill copy it.

[Papee]

Nice effort Dan. Do you have any better photos of the shape of the intake? The only suggestion I have concerning building your own intakes is pay attention to the inside of your intake. Spend some time making sure it is smooth as possible. If I had to take a guess on how that intake will perform it would be that it would be a bit sluggish but will do the job. With no real good view of it, it looks like the box is bigger, more volume than the tubes. You are going from the small tube to the box then into small tube again. I'm sure it will work with no harm to your motor but like I mentioned, may be a bit sluggish. Run it for a while then look at you plugs and see how they are burning.

[Bandit64]

Nice effort Dan. Do you have any better photos of the shape of the intake? The only suggestion I have concerning building your own intakes is pay attention to the inside of your intake. Spend some time making sure it is smooth as possible. If I had to take a guess on how that intake will perform it would be that it would be a bit sluggish but will do the job. With no real good view of it, it looks like the box is bigger, more volume than the tubes. You are going from the small tube to the box then into small tube again. I'm sure it will work with no harm to your motor but like I mentioned, may be a bit sluggish. Run it for a while then look at you plugs and see how they are burning.

Papee, I do have more pics, I'll load for you.
all the intake manifolds I looked at had small tubes connecting to a larger tube. Like I said I have no idea what I'm doing. If it turns out to be sluggish but works good I will spend the money for some pipe and do it so it all the same size. As far as the inside, its not real smooth. I know it should be but this is just a test.
But unless I built it in split halfs I'm not sure how to get in there to smooth it out. Especially if it was all small pipe. ????
what if I see that two cylinders are leaner then the others? What's the fix?

[Bandit64]

Maybe this view helps.

[Papee]

I'm working on a dual carb setup myself right now as well as a fuel injection system, it just takes time. If you look at any tuned intake it will not have and squared corners and some are even polished. I'm using all round tube for my intakes using some of the stock tubes. I am trying to come up with a design that will allow me to grind and finish all the connections as I go. Since these motors are much like a VW motor I decided to try the dual carb setup so I can tune each carb. It's a lot of work and not something that happens over night. Props to you for trying it yourself. The better an intake flows the better it will perform, each change in size or shape will affect the way the gas gets to the cylinder. Keep at it experimentation never hurts.

[Bandit64]

Here is a perfect example of what I said.
It's square tubing, large into small and a square cornered large section.

So where is the rime or reason to this one or other configurations I see on google images?

Paper, you know I've been asking about this for months now. I may be impatient but I just had another birthday so I know for sure that I'm not getting any younger. I plan on spending a lot of time on this boat but if I wait for someone else to make this thing happen ....

I've been interested in your idea and am not opposed to that either so hurry up would you.
Thanks, Dan
Oh, I know different pipe sizes will make different results but still haven't heard the fix to two cylinders lean.
Can Anyone give me a straight answer?

[Papee]

I really don't have any problems with the cylinders running different. When I look at my plugs they all look the same. I did have a problem when I first got the motor but the one cyl was a little weak because of it being a used engine. Is your motor hard to start when it's warm?

[Bandit64]

I really don't have any problems with the cylinders running different. When I look at my plugs they all look the same. I did have a problem when I first got the motor but the one cyl was a little weak because of it being a used engine. Is your motor hard to start when it's warm?

No. Mine starts right up. It was new in the crate when I got it.
Im not saying I will have a difference in the cylinders. It has been asked or mentioned by several people including chuck. Hopefully this is a mute point and mine will be balanced.

[Papee]

Yep, you never know until you try it. I'll have to look into the "box" or plenum type intakes and see what the idea is behind it. The cyl problems may be a symptom of running these motors at a higher RPM than I do. I rarely run mine above 3000 RPM.

[eskimoboy]

Hey guys check this out could be interesting.
http://groups.yahoo.com/group/J3kitt...rs/message/339

[Papee]

This part of that is important to read, it says a lot of what I am trying to get at with intake design.

Anytime you have a long span between the carburetor and
the cylinder ....fuel starts to separate from the
fuel & air mixture .......it starts to make little
puddles in the intake .....as it continues to idle that
fuel starts to get sucked towards the cylinder .....then
the cylinders start to get these teaspoon sized fuel
droplets getting ingested into the combustion chamber,
causing a really rich condition ......at idle this is
a problem .......but at higher rpms
the problem is not as big of a problem .....you get
these black puffs of smoke from the exhaust everytime
that rich fuel hits a cylinder .........but it will
continue to run.

With fuel injection the fuel is injected right at the
intake port of the cylinder ......only air flows through
the long intake tubes .....so it's no longer a problem.
Now not only is the amount of fuel correct for every rpm,
you can make your intake look like a pretzel if you want,
as long as the engine can get the amount of air it needs!
An added benefit is you no longer need carb heat or a
mixture control in the cockpit .......the amount of fuel
injected is based on RPM ......if your intake tubes are
too small or restrictive due to length or shape ...the engine
just runs at the highest rpm it can get air for....and the
ECM adds the correct amount of fuel .....in fact a leak
at the intake now is detected by higher than normal engine
speeds .......I set my idle for 750 rpm ......if I pull
off the vaccum line for the MAP sensor ....my engine
speed increases to 1000 because of extra air getting
past the throttle body butterflies.

Keep in mind that air will flow around a corner .....if
fuel is mixed with it ....fuel will separate from the air
every time the mixture turns a corner .....at every turn
you will loose fuel ......then what gets to the cylinder is
too lean ......

[Bandit64]

That's great info. I don't suppose either of you joined so you could view the pics?? If can u post them?
I mentioned the physics. This is the first it's been explained. Helpful.
It sounds like he's got it figured out. Getting past the 900. May take me awhile.
Thanks for posting it, dan

[eskimoboy]

Heres a pic of EFI