Vacuum Hose Routing to Cannister

[Jmac]

I used to have a vacuum supply to my cannister with the factory 307 engine I since changed the engine to a 350 Chevrolet I lost all vacuum to my cannister where can I possibly get a supply .Having trouble when braking unless I'm on the throttle to get more vacuum

 

[abbey castro]

if you are using a Q-Jet there is a port on the throttle plate backside of carb where the vac hard line is connected to pull vac for the booster. Its the hard line to the left of the intake manifold fitting w/rubber hose.

 

[Jmac]

if you are using a Q-Jet there is a port on the throttle plate backside of carb where the vac hard line is connected to pull vac for the booster. Its the hard line to the left of the intake manifold fitting w/rubber hose.

no the carb on it now is a dual feed Holley

 

[CopperNick]

Should still be ports on the Holley base plate for both continuous and ported vacuum. Principal difference is delivery; continuous is exactly as labelled, ported is a function of the throttle position.

You don't specifiy if your Holley has metering blocks both front and back or if the back is just a metering plate. Reason for my curiousity is that, on the manifold, at the back, between the dizzie body and the rear fuel bowl, is a vacuum port that is the typical default source for much of the vacuum demanded by various systems such as the brakes. Having the metering plate is a bit of an asset since it lets the fuel bowl sit closer to the carb body and leave a little more room to futz with the plumbing. The metering block,by contrast, pushes the bowl out about a 1/2 inch farther and it might then either cover or crash into a vacuum fitting or manifold port.



Nick

 

[Jmac]

Should still be ports on the Holley base plate for both continuous and ported vacuum. Principal difference is delivery; continuous is exactly as labelled, ported is a function of the throttle position.

You don't specifiy if your Holley has metering blocks both front and back or if the back is just a metering plate. Reason for my curiousity is that, on the manifold, at the back, between the dizzie body and the rear fuel bowl, is a vacuum port that is the typical default source for much of the vacuum demanded by various systems such as the brakes. Having the metering plate is a bit of an asset since it lets the fuel bowl sit closer to the carb body and leave a little more room to futz with the plumbing. The metering block,by contrast, pushes the bowl out about a 1/2 inch farther and it might then either cover or crash into a vacuum fitting or manifold port.



Nick

Ok Nick as I read you message I then rechecked the carb and yes there is a plugged port at the front

 

[CopperNick]

H-mmmm, Could be.................


Nick

 

[79 USA 1]

This may or may not help. On my 406 small block I have a Edelbrock Air Gap intake with a 750 Double Pumper. On the #8 intake runner behind the secondary fuel bowl is a threaded bung that I have an adapter to thread the power brake booster line into. I run this line up to the booster filter then up to a reserve vacuum can with a check valve. The return side of the vacuum can goes to the brake booster through another check valve.
The 3/8 hose port on the back of the Holley carb I use for the PCV line.


Fitting on intake.

Lines to vacuum canister and back to brake booster.


Hope this helps.

 

[CopperNick]

This may or may not help. On my 406 small block I have a Edelbrock Air Gap intake with a 750 Double Pumper. On the #8 intake runner behind the secondary fuel bowl is a threaded bung that I have an adapter to thread the power brake booster line into. I run this line up to the booster filter then up to a reserve vacuum can with a check valve. The return side of the vacuum can goes to the brake booster through another check valve.
The 3/8 hose port on the back of the Holley carb I use for the PCV line.


Fitting on intake.
View attachment 224492
Lines to vacuum canister and back to brake booster.
View attachment 224495 View attachment 224496 View attachment 224497

Hope this helps.

Great picture and exactly what I was referring to in the second half of my response.