boltnut

I don't want to get in a debate about what is better or why. I'm just curious how many out there are running manifold advance over ported. I would post a poll if I knew how. Maybe someone could do it for me.

No vac advance
Ported vac
Manifold vac

Just numbers. No opinions.

7t9l82

full vacuum

mds3013

Manifold. mike...

'75

Manifold vacuum

MotorHead

No vac advance

larrywalk

Full manifold vacuum advance (both vettes)

Alan 71

Hi bn,
For the mechanically challenged would you explain where the advance hose goes in each case.
NOT widening the debate.... just for info.
Thanks!
Regards,
Alan

larrywalk

You can hook from the vacuum advance canister directly to a tee or fitting on the intake manifold itself, or to a fitting on the carburetor.

However, not all carburetors are the same! Even among the same brand, the tube for full vacuum may located in different places and is a function of list number for Holleys, and Quadrajets are often different by model and/or year.

When you rebuild a carb, follow the passages and figure out which is which; alternately, if it's already on the engine, attach a vacuum gauge to each port/tube and read the vacuum at idle.

7T1vette

Nearly everyone is running vacuum advace on full 'manifold' vacuum...if they are running vacuum advance at all. Some folks don't run vacuum advance because their components don't need it...or they don't want it.

Those who run ported vacuum do it because "that's how it came from the factory" or because "that's the way it's always been" [since they've had the car]. There might be a few that find 'ported' vacuum actually works better...probably because there are other setup problems with the engine.

7t9l82

manifold vacuum on a carburetor is below the butterflies. ported is above, now someone will wonder why were discussing insects, and on it goes

73, Dark Blue 454

What he said. Many 70's and up models ran ported vacuum for emission reasons, but for performance on the street, manifold vacuum will provide better off-idle performance and a cooler running engine vs. ported.

Also, it doesn't make sense to disable vacuum advance for street driven rigs. The extra 10-15 degrees of advance at cruise will provide better mileage, and a more responsive throttle, in addition to a cooler running engine. Win, win, win, win, win.

On the quarter, where everything is full throttle (WOT) vacuum advance doesn't come into play though it won't hurt performance. And if you have to drive your rig to the track, why do without?

Mike Ward

So much for that.

Grumpy 427

Full vac on mine.I have tried both and the car works better on full.

redwingvette

I disconnected mine after I had Lars recurve my distribtor.

Alan 71

Hi,
Thanks for the info!
I really don't think the debate got started... at least not like it usually does!
Regards,
Alan

randyredleg

manifold

scottyp99

I have a line coming from ported and a line coming from manifold vacuum, to a tee, which goes to the vacuum advance canister.


Ha ha, just kidding!!! Manifold vacuum for vacuum advance is the way to go.


Scott

73, Dark Blue 454

Mike Ward,..how does this comment elevate or advance the discussion? In fact, let me ask you something publicly since you've no problem calling others out, publicly, over and over.

Since you posted this 'thought' just after my comments, did I post somthing that set you off? Whatever it was, I'll apologize in advance. In return, if you could simply post your comments and opinions without the need to call me out publicly (or your other fellow forum members), this board would be more enjoyable for all.

There is a PM function used by discerning members. You might try it.

To the OP, I also apologize.

Mike Ward

Did you miss the smiley? Jeeze, calm down!

73, Dark Blue 454

Oh,..guess I missed the forum policy that states it's ok to be snarky and rude to fellow forum members, but only if you post the cute little smiley face. Thanks for the tip on forum etiquette and policy.