holley carb and redline manifold install help

[GMH_VC]

has anyone done this i need to know were the vacum hoses go for the dizzy and what the best way to do it is. any help would be great thanks. it a blue 6 too forgot to mention that

[vkberlina]

It sould be connected to a ported vac switch so once the engie is warm you will get advance, when cold only base timng. So install a ported vac switch something that opens at aout 85degc would be fine. It can be connected to any vac source on te manifold.

ceers
Scot

[codfishface]

Doesn't ported vacuum mean the vacuum port is above the closed throttle valve?

So at idle there will be minimal vacuum signal, until the throttle is opened.

Taking vac signal from the inlet manifold will produce Max vac signal at idle, decreasing as the throttle is opened due to intake air entering the manifold.

I know SFA about Holleys tho, so disregard if necessary.

[Not_An_Abba_Fan]

Run it straight off manifold vacuum.

[ari666]

i am currently using ported vac, it gets 0 vac at WOT and full vac at deceleration. running of manifold vac works fine too, but you have to retard the sh1te out of your base timing.

it would be helpful to know what holley you are talking about so we can figure out where the connection is for it. failing that use a vac guage to find ported vac. failing that use your finger to plug the port. if it sucks while the engine is running try another one till you find the one that isnt sucking, then open the throttle half way and it should start sucking. thats the one you want.

[Not_An_Abba_Fan]

You shouldn't have to retard the base timing, as it is set with the vac adv unplugged anyway.

[GMH_VC]

Thanks for the help guys, will see how i go on the weekend.

[codfishface]

Shamelessly ripped from another site -

"Mounted on the side of the distributor body is a Vacuum canister module, inside the canister is a spring loaded diaphragm, prodding from this is a flat pull rod that is linked to the advance Breaker plate inside the distributor housing.

When the canister receives a vacuum signal from the engine, it in turn operates the diaphragm, the flat pull rod that’s attached to the Breaker plate securing the contact points, so it then rotates around the distributor cam, advancing the timing.

As the spring loaded diagram is operated by the throttle, it’s imperative the vacuum be received from above the butterfly, (atmospheric side).

Reason being is that when the throttle is at idle position then there is no vacuum to operate the Vacuum advance, this vacuum is called "Ported Vacuum" there is also "no load" here on the engine.

However, when the throttle is open, then the vacuum signal will be sufficient to operate the control diaphragm causing it to compress the spring and pull the breaker advance plate to rotate in a counter clockwise direction thus moving the contact points so distributor cam lobes open the points earlier in the compression stroke.
The movement in the throttle opening determines, in part, the amount of intake manifold vacuum and thus this then determines the amount of spark advance obtained.

This means that Manifold pressure during acceleration or pulling with wide open throttle, will not be strong enough to hold the breaker plate in the fully advanced position, so then the spring loaded diaphragm will then release its pressure allowing for the advance plate to return back to the fully/partly retarded position, depending upon the manifold vacuum available.

The advance obtained by the vacuum control is added to the Centrifugal/Mechanical advance."

As I have no EGR on my Black Carbed, I use this ported vacuum to control the Vac Advance. Being above the throttle valve, there is no vac at idle, therefore no advance.

[delcowizzid]

shame its wrong

[Not_An_Abba_Fan]

Haha..yep.

[codfishface]

shame its wrong

Cool.

I'm all ears. Point me in the right direction for a Black/Blue Six.

AFAIK, the early Varajets on the VC/VH's had a ported vac source on the carb, going through a Thermal Vacuum Switch, then to the Vac Advance.

EST VK's don't have this port as the Computer deals with the advance. My VK (no longer EST) has a reco Varajet (with no designated port) and HEI dissy with Vac Advance fed from the EGR vac source on the carb and is running purrfectly.

Might try it off the manifold on the weekend, but reckon it will be arse about face.

[Not_An_Abba_Fan]

Setting base timing is done with the vacuum hose disconnected. This puts the correct amount of timing in with it connected at idle. As the throttle is opened the vacuum advance lessens but the total advance increases as the mechanical advance takes over the faster the dizzy spins.

Running it through a ported vacuum would need more base timing as there would be no vacuum at idle. Then it would ping its head off at low revs because you have more vacuum than you should have advancing the timing.

[codfishface]

Thanks for that NAAF.

I'll have a couple of coldies tonight and try to get my head around it.

Cheers.

[GMH_VC]

ok so dose anyone one have any pics of there setup? As this would probably help as well.
is there one of these ported vac ports on a 350 holley?

[ari666]

like i said you can do it that way. i had nothing but troubles with manifold vac. wasnt until the dyno tuner connected advance to ported vac that i was able to get a decent amount of initial timing out of her.

anyways do what you want. factory advance on a 308 is connected to tvs which is manifold vac (advances the timing) till the engine warms up then is ported vac after that.

but yeah, whatever

350 should have a ported vac port on the base plate.

[GMH_VC]

yeah thanks people i got it all hooked up last night new manifold and and extrstors to. thanks for your help.