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Six Pack outer carb vacum ?

Mikke H

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At what point shall there bee vacuum to the outer carbs i tested the vacuum port at idle no vacuum tryed to rev but same result is there vacuum only under load ?
 
Correct. Should not be there at idle. The air passage is to the venturi. The air velocity through the center carb would need to be somewhat sustained. A fabricated 1/4" pipe tee to barb fitting attached to your compressor air hose can make a "jet pump" - similar to a siphon. You can attach each outboard to the bullhead on the tee and verify with the engine off.
 
The vacuum is created by air flow through the center carb, same as a four barrel. There won't be any at idle, or by blipping the throttle.
 
Ok how about this long hose into the car and hammer it there shoud bee a vacuum signal at 2500 or so ?
 
Vacuum is generated by air flow through the center carb. To check the end carbs action, suck on the hose, see if they react.
 
Yes they act but i dont feel any kick just a smooth transition upp too 5500 to 6000 grand nothing exiting looking for tiresmoke vibration black tire marks and sutsh MOPA
 
A good real world test, is to tie some yarn or a twist tie around the shaft from the vacuum canister and push it up tight against the housing. Make it just tight enough to stay put, and then go for a blast. If the secondaries are opening, the yarn will be down on the shaft the same amount as they opened. You might have to change the diaphram springs.
 
Yes they act but i dont feel any kick just a smooth transition upp too 5500 to 6000 grand nothing exiting looking for tiresmoke vibration black tire marks and sutsh MOPA

just a smooth transition upp too 5500 to 6000

This is how it is supposed to work !! If you want "kick",change the springs,you may find your expectations are not what you expect !!
 
Smooth is what I want. But change the end carb springs to get sooner opening.
 
Ok now this is my new set off carbs they are bone stock unmolested set ,the set that came whit the car had a different mode off operation they gave a clear kick att about 2500 rpm and i asumed that is how they work !So what you are saying is that smooth is how they are setup from start ?
 
If the outboards come in too quickly, you will get a bog. Remember there are no accelerator pumps in the outboard carbs. That is why the transition has to be a little slow.
 
Generally speaking, if you take your stockish street car to the track, and experiment with outboard carb opening rate to achieve the lowest et and hightest mph, you will find that there will be a very noticeable surge when the outboard carbs come-in on the street from a roll. We've proven this time and time again. And conversely, if you slow down the outboards so that there is no noticeable surge with WOT from a roll, you just slowed the car down probably .3 sec, and 2 mph.
 
Ok thanks for all tips i wont start to fiddle with the outer carbs stock is god inuf for me just vanted to know how the sekonderies vas ment to operate .
 
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