Just looking at the Edelbrock Carb Installation Video and i'm presented with 2 different vacuum ports.

Can you tell me if the 425 Super Rocket (1965) uses "Ported/Timed Vacuum" or "Manifold Vacuum" ?

thanks

 

To be picky, the motor doesn't use vacuum, it generates it. Various devices on the car use either manifold or ported vacuum. Transmission vacuum modulators, for example, will use manifold vacuum while distributor vacuum advance originally uses ported vacuum. Which is used depends on what device is using it.

 

OK, so coming from the original Rochester carb, i have a steel line that goes to the trans and a rubber hose that hooks up to the dizzy.

The Edelbrock carb has 2 barbs, one for manifold vacuum and one for ported/timed. Do I simply hook up the distributor pipe to the ported barb and the tranny to the manifold barb??

sorry, this is my first attempt at an intake and carb upgrade!!

 

Don't forget that your power brakes take manifold vacuum as well. There should be a large port behind the carburetor for your power brakes.

 

I'm guessing that's the one with the 1/4" brass barb fitting just behind the carb?

 

Yes

 

Thanks guys,
Great help as always!

 

On the '66, both the distributor and the trans modulator are connected to the ported vacuum. The carb has only one fitting and there is a tee in the line that branches to both places.

 

yes that's how it's set up on my original carb.
the trans is a metal line that screws in and the distributor hose is t'd off of that.

I guess I should copy this set up on the new carb?

what would happen if i did one to manifold and the other to ported?

 

Also, are the consequences big if I block off the PCV valve?

 

Crankcase pressures up and pushes oil out wherever it can push it out at. The more blow-by you have the greater the problem is. I'd advise to maintain the PCV system fullly functional.

 

Ported, same as any other Olds with vacuum advance.

You are half right. Distributor does use "ported/timed" vacuum, but the trans (like any other Olds with a vacuum modulator) needs "full time" vacuum to work properly.

From the '66 Chassis Manual:




Norm

 

Ported to modulator and manifold to advance would work, but not as well as the factory setup. Try it for yourself, it won't hurt anything.

To say that pressure builds is an exaggeration. Fumes would simply escape into the air filter and be sucked into the carb.

Good advice.

Unless you like changing air filters, and cleaning oily residue out of the carb.

Norm

 

[quote=You are half right. Distributor does use "ported/timed" vacuum, but the trans (like any other Olds with a vacuum modulator) needs "full time" vacuum to work properly.[/quote]

took the car out today and it seemed to have trouble shifting up gears.
When i assembled the vacuum lines I put my tranny vacuum hose to "ported", could this be the problem?

 

http://www.urbandictionary.com/define.php?term=tranny


Think of the "port" as a valve.

At idle, it is closed and there is no vacuum. Above idle, the "port" opens and vacuum is drawn from the manifold. This combination is needed for the economizer (power) valve and the vacuum advance to work properly.

The "modulator" uses manifold vacuum to control the timing of the shifts.

High vacuum = shifts at lower speeds.
Low vacuum = Shifts at higher speeds.

If, it does not have sufficient vacuum it will not change gears.

Norm

 

well that explains that then
thanks

 

??
yeah can't wait to take it down the drag strip

http://www.urbandictionary.com/define.php?term=drag

 

All I can say, Norm, is that growing up in straight-laced New England in the 1960s and 1970s, "tranny" was definitely slang for transmission.

What else COULD it have meant?

Of course, on the left coast, anything goes...

 

 

Now your slamming my left coast? Man wheres the respect

 

Not a "slam". An acknowledgment that everything begins here.

For example, our "speaker of the house" (name withheld, to keep it from becoming political) and "everything" she has been "starting".

Norm

 

Got your point Norm

 

Cruise the Sunset Strip in West Hollywood?

http://www.urbandictionary.com/define.php?term=Cruising

I never made the connection.

Norm