position for ITB vacuum reading
Discussion
I'm going to add some nipples into an intake manifold for purposes of using a carb sync tool for balancing throttles using vacuum signal. Is there any guideline on where to put them? i have 6 " of length between blade and head.
i presume you dont want them to be too close to the throttles, but maybe im wrong and it doesnt matter ?
cheers
i presume you dont want them to be too close to the throttles, but maybe im wrong and it doesnt matter ?
cheers
i was just worried that if they were close to the butterflies then unless they were each exactly positioned in the same position around the circumference and distance from the blade that it was more likely to introduce variation, as looks quite chaotic just down stream of the throttle in CFD ive seen
i can get it about 5/8"-->3/4" downstream from throttles, presumably on the bottom is ok to as the injectors and connections are sort of in the way on top unless i put them in at a slight angle
https://i.ytimg.com/vi/m2IzJlaEu9Q/hqdefault.jpg
thanks
i can get it about 5/8"-->3/4" downstream from throttles, presumably on the bottom is ok to as the injectors and connections are sort of in the way on top unless i put them in at a slight angle
https://i.ytimg.com/vi/m2IzJlaEu9Q/hqdefault.jpg
thanks
If you have them downstream the depression will collapse as soon as you open the throttle as it will be max vac reading with throttles closed, the idea is to get a 'good' signal by having it slightly upstream of the throttle disc/butterfly so it comes into play as the disc opens and presents higher speed air flow to the take off.
Unless for some reason you require max vac only at idle?
Peter
Unless for some reason you require max vac only at idle?
Peter
Edited by PeterBurgess on Thursday 13th October 08:46
PeterBurgess said:
If you have them downstream the depression will collapse as soon as you open the throttle as it will be max vac reading with throttles closed, the idea is to get a 'good' signal by having it slightly upstream of the throttle disc/butterfly so it comes into play as the disc opens and presents higher speed air flow to the take off.
Unless for some reason you require max vac only at idle?
Peter
Say what? How do you propose the OP balances his TBs at idle if he puts the take off point upstream of the butterfly?Unless for some reason you require max vac only at idle?
Peter
Edited by PeterBurgess on Thursday 13th October 08:46
Edited by KiaDiseasel on Thursday 13th October 15:02
Inline__engine said:
i can get it about 5/8"-->3/4" downstream from throttles, presumably on the bottom is ok to as the injectors and connections are sort of in the way on top unless i put them in at a slight angle. thanks
I wouldn't fret too much about them being a little way down the manifold from the butterflies. You get some pressure recovery as you go further away from a restriction so the signal will be a bit weaker but anywhere up near the TB end of the manifold will do.Edited by KiaDiseasel on Thursday 13th October 15:01
PeterBurgess said:
If it is only for balancing then it is covered by my...Unless for some reason you require max vac only at idle?
Peter
Well I guess it's an understandable mistake given how unclear the original post was. If only the OP had said something like "for purposes of using a carb sync tool for balancing throttles".Peter
Oh......
I use a single vacuum gauge and have an adjustable clamp on the hose so I can damp out the pressure oscillations to an acceptable level for obtaining repeatable readings. I used to yearn for those multiple manometers you could buy for setting up bike carbs many years ago! I would be wary of using multiple Bourdon vac gauges as they may not give like for like readings due to manufacturing/calibrating differences.
Peter
Peter
i have a gauge http://www.carbtune.com/ for each cylinder, has a small pin sized orifice piece that goes in the hose to filter fluctuations
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