I am putting an L79 manifold and Holley carb on my 65 SS with a 327 to get a little more out of it. The carb is an 1850-3, similar to a 4160 with no secondary metering block and vacuum secondaries.

I have three items requiring vacuum and the choice is mine since the set up is completely different from the stock intake. I need to get vacuum to the power brakes, vacuum advance and a large hose from the oil filler pipe in the front of the motor (old style) to scavenge the back pressure from the bottom end.

The carb has three vacuum inputs, a small port from the side of the primary metering block that I assume goes to the vacuum advance, a small one on the front base plate below the front primary plate, and a large one in the rear base plate that goes below the secondaries. I though the oil breather line would go to the air cleaner and the power brakes would come from a tee directly into the manifold, but the vacuum advance I am not sure of. I am open to any educated inputs.

Thanks Guys!
Chuck

The vacuum advance goes to the small line on the side of the primary metering block.

Dave

You want full manifold vacuum, not ported.

Thanks Dave. That confirms what I thought.

Patrick, Are you saying I need full manifold vacuum for advance????
How do I explain the attached L79 picture?

Thanks
Chuck

Unless you are controlling some smog equipment, I would hook everything to full manifold vacuum. Your vacuum advance won't bring the advance in at idle if hooked to ported vacuum.
It's your engine, you don't have to explain anything to anybody.
Squido

Thanks Dave. That confirms what I thought.

Patrick, Are you saying I need full manifold vacuum for advance????
How do I explain the attached L79 picture?
Thanks
Chuck
Full manifold vacuum is what you want. Read here:
http://www.460ford.com/viewtopic.php?t=21911&highlight=&sid=7dc14d08f98723a0636d73f6ff09a8ce

Full Int Vacuum For Vac Adv,not Ported.

Scott

Perfect! Sometimes it's hard to decide here. There are lots of opinions. Thanks guys.

Full vacuum it is.

Chuck

That port on the side of the metering block on the Holley provides manifold vacuum. At least it does on my Holley.

That port on the side of the metering block on the Holley provides manifold vacuum. At least it does on my Holley.
On my holley 3310 that port is ported. I'm not sure on others.

How can you tell? Can you measure the vacuum? I'd rather use the stock location. My carb is not an L79 original carb, just one from the same period. I need to make sure it will work. Any ideas?

Chuck

Hook a vacuum gauge up to the port, if it is ported vacuum there will be little to no vacuum until you open the throttle plates.
If the port is straight manifold vacuum it will have vacuum the same as the ports used for your brake booster, and decrease when the throttle plates are opened.
Squido

Thanks pal! You always seem to have the answers. I can't tell you how much your contributions to Team Chevelle mean around here.

Chuck