distributor vaccum?

[trickedout420]

where should my distributor get its vaccum from? i have it hooked up to the screw in vaccum port on my intake. i was wondering if i should move it to my carb on the timed vaccum port because my truck is still bucking and shaking like hell. so its not a fuel problem anymore its a timing problem.

should i run timed vaccum or manifold vaccum? its for my vaccum advance

[FordeatinZ71]

for the vac advance to work as it was intended, you want it to be fed by a ported vac source. see, manifold vacuum drops off as RPMs/load increase...ported vac signal increases...which is what you need...

[Ivan D.]

for the vac advance to work as it was intended, you want it to be fed by a ported vac source. see, manifold vacuum drops off as RPMs/load increase...ported vac signal increases...which is what you need...
No, that's just the opposite of what you want - your rpm-related advance is handled by the centrifugal weights mechanism under the cap, the vacuum can is there to provide the load-related advance. Vacuum advance should be hooked up to a manifold vacuum source (be it an actual manifold port, or a port at the base of the carb), this way the dizzy can react to changes in engine load and avoid over-advancing and causing a detonation.

[FordeatinZ71]

well, i guess what he said then. i googled this because i wasn't sure and that's why i posted what i did. guess there are a couple of people out there that have messed up running trucks...

[trickedout420]

i could hook it up and try edelbrock tech told me to try it.

[retired wrench]

You will have the same amount of vacum at either place. On the manifold you will have full vacum at idle where on the carb you wont. Shouldnt affect the performance either way but will affect the idle speed. Under a heavy load or wide open throttle you wont have much vacum at either place. RW

[dave89iroc]

ported if idle emissions are your primary concern, manifold if performance it your primary concern

[bored&stroked]

ported if idle emissions are your primary concern, manifold if performance it your primary concern

To add to that, manifold if nice drivability is what you want. Ported is for emissions only. Both sources give the same vaccum signal and loose vaccum at max throttle/rpm.

[retired wrench]

I agree with bored& stroked,todays mantra is ported vac retards timming at idle and burns fuel more completely,like it is something new.They have used ported vac since the 30s when emission wasnt even in the dictionary.When you floor it at a stop light it wont matter where you have it hooked unless you have a duplex fuel pump. RW