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Author Topic: Single Carb Manifold?  (Read 12098 times)

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Offline faux fiddy

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Single Carb Manifold?
« on: February 04, 2011, 01:40:37 AM »


I've thought this would be an alternative to the dwindling out supply of worn out 350f carbs.

I have a flat slide I have thought would work if I fab'd a manifold, but a friend says it will rob performance.


Anyone got info on this modification?   Will it, or has it worked?
« Last Edit: December 15, 2011, 02:33:23 AM by fiddy of industry »
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Offline dave500

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Re: Single Carb Manifold?
« Reply #1 on: February 04, 2011, 02:23:05 AM »
things that look good ,look good,shorter and straighter even length runners maybe?how about dual stage throttles,if that stuff was any good it would already be out there i think,sometimes i think wrongly though,candidate for a small su?
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Offline Terry in Australia

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Re: Single Carb Manifold?
« Reply #2 on: February 04, 2011, 02:36:42 AM »
I dunno aboot 35F stuff mate, but there are/were many different options for single and dual carb manifolds for the mighty CB750. That thing in your pic looks more like someone's attached an exhaust header to the inlet side of the head. Cheers, Terry. ;D
« Last Edit: February 04, 2011, 05:18:56 AM by Terry in Australia »
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Offline faux fiddy

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Re: Single Carb Manifold?
« Reply #3 on: February 04, 2011, 03:06:25 AM »
Quote from: dave500 on February 04, 2011, 02:23:05 AM
things that look good ,look good,shorter and straighter even length runners maybe?how about dual stage throttles,if that stuff was any good it would already be out there i think,sometimes i think wrongly though,candidate for a small su?

Prolly right about that.

What was in my imagination was similar, but the outside cylinders would get the straight shortened and the inner two would be curved to equal the length.

I found that pic on the recent engine paint  thread .

I wanted to do it just to motivate a start with a backyard foundry.
« Last Edit: February 04, 2011, 03:08:12 AM by tree fiddy of industry »
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Offline dave500

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Re: Single Carb Manifold?
« Reply #4 on: February 04, 2011, 03:26:41 AM »
shudder,chrysler hemi six long branch manifold with a two barrel,so uneven,not shudder six pack hemi with dellortos.
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Offline Tom in Newcastle......Ontario

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Re: Single Carb Manifold?
« Reply #5 on: February 04, 2011, 06:02:13 AM »
Quote from: tree fiddy of industry on February 04, 2011, 01:40:37 AM


I've thought this would be an alternative to the dwindling out supply of worn out 35f carbs.

I have a flat slide I have thought would work if I fab'd a manifold, but a friend says it will rob performance.


Anyone got info on this modification?   Will it, or has it worked?


 What you are seeing in this pic is the exhaust..........http://www.dotheton.com/forum/index.php?topic=19961.0


but of course I have been wrong before ........ ???
« Last Edit: February 04, 2011, 06:06:54 AM by tjjkc »
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Offline lrutt

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Re: Single Carb Manifold?
« Reply #6 on: February 04, 2011, 06:16:07 AM »
Regardless of what it is exactly you are showing in your picture, those runners are just way too long. You have to shorten them down considerably. Better to make a plenum arrangement right at the intake ports then mount a nice 40 cv or something similar. Would be fairly simple.
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Offline Mandic

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Re: Single Carb Manifold?
« Reply #7 on: February 04, 2011, 06:17:53 AM »
That is the exhaust guys.  That engine is in a project in the "project shop" i believe.  He reversed the head mounting so the intake ports are on the front of the engine and the exhaust exits out the back.
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Offline Deltarider

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Re: Single Carb Manifold?
« Reply #8 on: February 04, 2011, 06:58:36 AM »
Just came in after visiting a friend who's working on a 350. He uses the same as exhaust...
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Offline fire113

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Re: Single Carb Manifold?
« Reply #9 on: February 04, 2011, 07:13:19 AM »
looks funny  ;D

but the problem will be the filling of the cylinders because the different length!
1&4 has much longer ways then 2&3.

Good luck...Georg
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Offline faux fiddy

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Re: Single Carb Manifold?
« Reply #10 on: February 04, 2011, 07:16:42 AM »
Quote from: Mandic on February 04, 2011, 06:17:53 AM
That is the exhaust guys.  That engine is in a project in the "project shop" i believe.  He reversed the head mounting so the intake ports are on the front of the engine and the exhaust exits out the back.

Can that be done on a 550?

I've seen that on triumph twins, but I think other pics of this motor show stock intake manifolds.
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Offline Terry in Australia

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Re: Single Carb Manifold?
« Reply #11 on: February 04, 2011, 06:34:51 PM »
Yeah, of course you can mate, and it's easy, you just install the exhaust on the inlet side of the head and a set of carbs on the exhaust ports, and fire that sucker up! ;D

Seriously, I went thru that whole thread and there's no evidence that Joey Putt actually reversed anything, I'm guessing that he's a "fabricator", not a mechanic, and doesn't have a clue. He's posted that he'll have it running soon, but I wouldn't hold my breath mate, it aint gonna happen anytime soon............  ::)
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So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline dave500

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Re: Single Carb Manifold?
« Reply #12 on: February 04, 2011, 07:35:48 PM »
that head aint backwards
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Offline Deltarider

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Re: Single Carb Manifold?
« Reply #13 on: February 05, 2011, 03:34:15 AM »
Quote
that head aint backwards
Who's head? ;D
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Offline dave500

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Re: Single Carb Manifold?
« Reply #14 on: February 05, 2011, 03:57:37 AM »
my heads been inside out in the past(70s,its just the way it was then,boy am i glad that phase is over.)but never backwards.
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Offline faux fiddy

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Re: Single Carb Manifold?
« Reply #15 on: February 05, 2011, 04:24:10 AM »
Quote from: dave500 on February 05, 2011, 03:57:37 AM
my heads been inside out in the past(70s,its just the way it was then,boy am i glad that phase is over.)but never backwards.

Mine wasn't screwed on tight and I lost it. Anyone seen it around?
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Offline dave500

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Re: Single Carb Manifold?
« Reply #16 on: February 05, 2011, 04:56:02 AM »
oh sorry tree fiddy,was that yours?,ill just fish it out of the dogs mouth,hes having a good chew.
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Offline faux fiddy

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Re: Single Carb Manifold?
« Reply #17 on: February 05, 2011, 07:22:55 AM »
Quote from: dave500 on February 05, 2011, 04:56:02 AM
oh sorry tree fiddy,was that yours?,ill just fish it out of the dogs mouth,hes having a good chew.
Send me a postage quote- I'll do a pay pal.
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Offline Old Scrambler

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Re: Single Carb Manifold?
« Reply #18 on: February 05, 2011, 08:36:46 AM »
C'mone now and use your head!........if you reverse the wires on the starter motor.........that will spin the motor backwards and its should run with that setup for intake and exhaust!  To fix the drive-line just install a belt drive with a twist! Life is simple.......as in the '70s!!!
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Offline mlinder

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Re: Single Carb Manifold?
« Reply #19 on: February 05, 2011, 09:03:25 AM »
When MV was about to make their comeback in, oh, whatever it was, 97, their initial design was intake on the front, exhaust out the rear.

I mean, it makes sense.. However, engine placement becomes an issue. It requires that the engine mass be moved further back, which is not really a good thing, especially for performance bikes.

The one posted above, well, i didn't read anything about it, but he's got what looks like some brand of carbs with a ram-air bellmouth. I didn't see anything obvious that showed a pressurization of the bowls, which means at speed, he'll be pushing air down the jet instead of drawing fuel up through it. Which means we will never be at speed.. lol.

Unless those carbs are designed differently that uh, most carbs.
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Offline faux fiddy

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Re: Single Carb Manifold?
« Reply #20 on: February 05, 2011, 09:18:08 AM »
Quote from: mlinder on February 05, 2011, 09:03:25 AM
When MV was about to make their comeback in, oh, whatever it was, 97, their initial design was intake on the front, exhaust out the rear.

I mean, it makes sense.. However, engine placement becomes an issue. It requires that the engine mass be moved further back, which is not really a good thing, especially for performance bikes.


Might be something to it.

















« Last Edit: February 05, 2011, 09:23:28 AM by tree fiddy of industry »
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Offline mlinder

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Re: Single Carb Manifold?
« Reply #21 on: February 05, 2011, 09:25:40 AM »
Sure, i's been done, but I don't see his pressure issues addressed. And like I said, it will screw with weight balance on performance bikes.
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Offline Gearheadgreg

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Re: Single Carb Manifold?
« Reply #22 on: February 05, 2011, 10:33:13 AM »
The only 750 four i have seen with the head 180  is Russ Collins Sorcerer back in the seventies,,read page 45 at bottom. http://forums.sohc4.net/index.php?topic=67576.0
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Offline Don R

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Re: Single Carb Manifold?
« Reply #23 on: February 05, 2011, 10:45:25 AM »
Most automotive engines do not have a venturi per cylinder so adequate performance could be achieved. Runner length depends on rpm range and pulse tuning. You would not want low points that would cause fuel puddling. Most people aren't willing to do the work involved to get one correct.
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Offline Roach

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Re: Single Carb Manifold?
« Reply #24 on: February 05, 2011, 10:58:01 AM »
Quote from: tjjkc on February 04, 2011, 06:02:13 AM
Quote from: tree fiddy of industry on February 04, 2011, 01:40:37 AM


I've thought this would be an alternative to the dwindling out supply of worn out 35f carbs.

I have a flat slide I have thought would work if I fab'd a manifold, but a friend says it will rob performance.


Anyone got info on this modification?   Will it, or has it worked?


 What you are seeing in this pic is the exhaust..........http://www.dotheton.com/forum/index.php?topic=19961.0


but of course I have been wrong before ........ ???
its his exhaust running out the back look in the project shop on the reverse port project. it should work just fine he didn't just go sticking an exhaust on the opposite sides he flipped the valves to the other side and needed to get a custom cam grounded so that the exhaust lifts where the intake lifted and the intake lifted where the exhaust does. should work that way there is no reversing of anything. in principle  it should work just a matter of getting the afr right it will be taking in allot more air.

by no reversing od anything i mean the cam chain still runs the same direction
« Last Edit: February 05, 2011, 11:00:44 AM by Roach »
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