tue or false, you'll lean sieze a single carb 62t at WOT

Putting a single carb on a 62t case will sieze a motor on WOT runs.

  • True

    Votes: 4 14.8%

  • False

    Votes: 23 85.2%
  • Total voters
    27
WaveDemon

WaveDemon

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I've seen this mentioned a bunch of times and I don't see how its possible. The rumor I've read is that if you put a single carb on a 62t and run it WOT you will seize it.

My understanding of carbs will not allow me to believe this is true.

I've owned a 62t/62t motor with a riva single carb manifold with a single OEM 44 carb on it and had plenty of WOT runs.

I've owned a ported 86mm 61x (bottom)/ 62t (top) motor with a few different single carbs with WOT runs with no problems.



If I try to make a case for the seizure I would say that the fuel pump can't keep up because each cylinder will pull off of a 44 carb throat worth of air and only get fuel from one pump (instead of one 38 with pump per cylinder).

I can blow that out of the water though because there are plenty of dual 44 carb set ups out there with only one of the carbs with a fuel pump and the other with a block off.

hell, I think a single 38 will work just fine on a 62t motor with no lean WOT problems


can anyone shed some light on how a lean seizure will happen with a single carb?
 
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SuperJETT

SuperJETT

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With a certain setup, yes.

I had a Novi 48/Riva single manifold/external big fuel pump on mine and even with the main jet *removed* and the high screw at like 3 turns out, I could not richen it up. I could not hold it WOT or the rpms would peak and drop off way quick which leads to a seizure normally. Did it seize? No, but I also know to let off before that happens.
 
DAG

DAG

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Location
Charlotte, NC
what does single carb half to do with anything? If its lean on duel or single setup's its gonna seize...? I must be missing somehting here..

anywho, should ask "who has seized a motor on a single carb on a WOT run"
a true/false poll is giving you people just clicking a button for the ******** of it .02
 
WaveDemon

WaveDemon

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Hell, Florida
Matt_E said:
I don't see *how* it's possible either, but facts rarely play into convictions.
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well, when a motor building states this it makes me wonder where my thinking is wrong.


I'll go out on a limb and say that running a single 44 on a good manifold will preform just as good as a double set up.

here is why- how many 44 carbs is a cylinder drawing from on a dual set up? ...one.
 
WaveDemon

WaveDemon

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SuperJETT said:
With a certain setup, yes.

I had a Novi 48/Riva single manifold/external big fuel pump on mine and even with the main jet *removed* and the high screw at like 3 turns out, I could not richen it up. I could not hold it WOT or the rpms would peak and drop off way quick which leads to a seizure normally. Did it seize? No, but I also know to let off before that happens.
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are you sure there was no air leak, used a restrictor in the return line. it still doesn't make sense to me. I must have gone simple. :icon16:
 
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Matt_E

Matt_E

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Exactly. But a carb on a dual setup is getting at least 180 degrees crank rotation of "rest", while a single carb setup is busy the entire 360 degrees.

Not sure what the big difference is between X and T cases. Why a seizure on one and not the other?
 
WaveDemon

WaveDemon

Not Dead - Notable Member
Location
Hell, Florida
Matt_E said:
Exactly. But a carb on a dual setup is getting at least 180 degrees crank rotation of "rest", while a single carb setup is busy the entire 360 degrees.
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there are plenty of motors out there that have a plenum with 4-8 cylinders drawing off of a single carb. I don't think a carb resting between rotations is even a benefit to performance.


Matt_E said:
Not sure what the big difference is between X and T cases. Why a seizure on one and not the other?
Click to expand...
exactly!
 
SuperJETT

SuperJETT

So long and thanks for all the fish
Location
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WaveDemon said:
are you sure there was no air leak, used a restrictor in the return line. it still doesn't make sense to me. I must have gone simple. :icon16:
Click to expand...

Trust me, I am decent on carb setups and went through everything, and that's what led me to trying it with no main jet at all.

WaveDemon said:
here is why- how many 44 carbs is a cylinder drawing from on a dual set up? ...one.
Click to expand...

On my setup, I believe it was due to Novi's internal mods limiting max fuel flow. On others, it's a limit of how much fuel the pump can put out.

I have the notes out in the garage, but it's something like one body mounted fuel pump is good for 110hp @ 6000rpm, and it does extrapolate fairly linearly so 7000rpm is ~128hp.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
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The instantaneous fuel flow through a single 48 Novi shouldn't be any different than dual 48 Novis.

Right?
 
W

waxhead

wannabe backflipper
Location
gold coast
Thats would be awesome if the carbs were only flowing for 180 degrees of the intake cycle per cylinder but with the ram effect due to the weight of the air then you will find that the intake cycle is longer in duration

You also have to remember that when the reeds shut they send a pressure wave back up the inlet that confuses the carb for the other cylinder thats trying to flow

But hey a single is better on gas which means its not flowing as much air/fuel which means you are down on power
 
butti

butti

lone wolf
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chrisdoc0608 said:
I really dont want to start an argument. You know who it was so you can call them out
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im sorry,i wast aware of that other thread.im certainly not calling anyone out.it just cracks me up sometimes how one person can make a statement on the internet,then a dozen other people read it and regurgitate it a few times and all of a sudden its fact.


by the same token i dont completey dismiss the idea that a single can lean a motor out at high rpm(note darins posts) but i think its probably very uncommon
 
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