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Discussion Starter · #1 ·
On my edelbrock 1406 there are two 3/16 vacuum ports on the front. The left one is for timed vacuum, and the right one is for manifold vacuum. Also the carb manual says the left is for emissions controlled engines, and the right is for non emissions. Since the motor is no longer emissions controlled, what port should be used? Does one port work better over the other?
 

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Discussion Starter · #4 ·
Thanks guys, that helps. Heres a quote from that link -

"For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively. Don't ask Summit or Jeg's about it – they don’t understand it, they're on commission, and they want to sell "race car" parts".

So I want manifold vacuum not timed vacuum? Then it would be the port on the right?
 

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I run both manifold and ported vacuum as it was stock. I used the temp vac switch on the t-stat housing and "Y"ed it to both ported and manifold vac on my edelbrock carb.
 

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use the timed port otherwise you will be running full advance all the time.
:stupid

I used the temp vac switch on the t-stat housing and "Y"ed it to both ported and manifold vac on my edelbrock carb.
Going the stock route, you dont "Y" the ported and manifold vac to the dizzy. One is for ported vac at cold and normal temps, the other is for manifold at hot temp to increase rpm for cooling. Y-ing them together will just give you full manifold vac.
 

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:stupid



Going the stock route, you dont "Y" the ported and manifold vac to the dizzy. One is for ported vac at cold and normal temps, the other is for manifold at hot temp to increase rpm for cooling. Y-ing them together will just give you full manifold vac.
:doh0715:
Its pretty clear you dont know what you're talkin about. The temp vacuum switch feeds manifold vacuum when cold and ported vacuum when operating temp is reached. Sorry I used the wrong letter to decsribe the hose routing, but if you didnt get the point you're a lost cause anyway. Just incase you cant paint the picture in you're head, heres the routing-

Manifold vacuum is connected to the #1 nipple.
Ported vacuum is connected to the #2 nipple.
The hose to the dizzy goes to the center nipple on the switch, marked 'D'.
 

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:doh0715:
Its pretty clear you dont know what you're talkin about. The temp vacuum switch feeds manifold vacuum when cold and ported vacuum when operating temp is reached. Sorry I used the wrong letter to decsribe the hose routing, but if you didnt get the point you're a lost cause anyway. Just incase you cant paint the picture in you're head, heres the routing-

Manifold vacuum is connected to the #1 nipple.
Ported vacuum is connected to the #2 nipple.
The hose to the dizzy goes to the center nipple on the switch, marked 'D'.
Since I am too lazy to look it up in the Shop Manual. Have you installed the temp switch in the water neck or the intake?
 

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I installed it in the stock location, the t-stat/waterneck housing.
 

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OK. I got off my ass and dug out the book. Per 1978 Ford Truck Shop Manual:

PVS (Ported Vacuum Switch)

"These switches are used in several places in the emissions control system. Used with two, three, or four ports, the valves can be used to turn vacuum on and off, or switch between two vacuum sources for a 3rd delivery point.

When cold, the typical three-port PVS provided a path through the center and top ports. When hot, the top port is closed off and the center and bottom ports are connected. In the case of the cooling PVS, the distributor vacuum advance diaphragm normally receives its vacuum signal from the carburetor spark port. If the engine should overheat while idling, the PVS connects the distributor to full intake manifold vacuum, thus increasing the engine speed until cool-down occurs. Then the engine temperature drops, the PVS once again connects the distributor to the spark port."

This reads the opposite of what you are running.
 

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Werd. And if you properly maintain your cooling system and cooling fan, it should never have to switch. BTW, when the engineers came up with that strategy, they forgot one thing--too much advance on a very hot engine can cause pinging. The EGR was supposed to help with that, but how many idiots removed theirs??!!!
 

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Im not sure where you got that quote, but the logic is kinda backwards and only describes the tvc function in overheating conditions. The real function of the tvc is to help cold starting and warm up by using full manifold vacuum when started instead of having no vacuum at idle and above a certian rpm with the ported vacuum.
 

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I agree that the logic seem backwards.

It is on page 29-01-2 of 1978 Ford Truck Shop Manual Vol. 2 Engines.
 

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I just got done with dialing in the carb (Motorcrap 2150) and dizzy on my '79 'Chero yesterday, and it's set up the way Winder describes it. First of all, you don't need full vacuum on your advance with a properly set choke; the high and curb idle steps keep the engine speed up during warm-up, and you don't need gobs of power during warm-up anyway. Second, the only time you need full advance at idle is with an overtemp condition.
 

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:doh0715:
Its pretty clear you dont know what you're talkin about. The temp vacuum switch feeds manifold vacuum when cold and ported vacuum when operating temp is reached. Sorry I used the wrong letter to decsribe the hose routing, but if you didnt get the point you're a lost cause anyway.
PVS (Ported Vacuum Switch)

"When cold, the typical three-port PVS provided a path through the center and top ports. When hot, the top port is closed off and the center and bottom ports are connected. In the case of the cooling PVS, the distributor vacuum advance diaphragm normally receives its vacuum signal from the carburetor spark port. If the engine should overheat while idling, the PVS connects the distributor to full intake manifold vacuum, thus increasing the engine speed until cool-down occurs. Then the engine temperature drops, the PVS once again connects the distributor to the spark port."

:rolleyes: Way to be an asshole and a dumbass at the same time.
 

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The full vacuum advance and choke are meant to work together for startup and aid in reaching operating temp in colder climates.
:rolleyes: Way to be an asshole, dumbass
You and you're childish wisdom are beyond me cause what you just posted had nothing to do what I said earlier.
 

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The full vacuum advance and choke are meant to work together for startup and aid in reaching operating temp in colder climates.


You and you're childish wisdom are beyond me cause what you just posted had nothing to do what I said earlier.
No, it is not! The vacuum advance is NOT supposed to have any full vacuum between idle and 1400-2000 rpm, depending on the specific engine model. So when the high idle is set, only the mechanical advance is bringing up the timing (typically 18-22* @ 2500 RPM), so the vacuum advance doesn't even tip in during engine warm-up. I've owned more carbureted Fords than I care to shake a stick at, and three of my mechanic jobs have been (and are) at shops that specialize in driveability diagnosis and repair.
 

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Discussion Starter · #20 ·
No, it is not! The vacuum advance is NOT supposed to have any full vacuum between idle and 1400-2000 rpm, depending on the specific engine model. So when the high idle is set, only the mechanical advance is bringing up the timing (typically 18-22* @ 2500 RPM), so the vacuum advance doesn't even tip in during engine warm-up. I've owned more carbureted Fords than I care to shake a stick at, and three of my mechanic jobs have been (and are) at shops that specialize in driveability diagnosis and repair.
How would you know? Are'nt you the guy who thought these 78-79 rigs had ttb?
 
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