I'm swapping my edelbrock carb for a holley 750cfm...

is this where the vacuum line from the valve cover goes?? i can't remember the name of it right now..

i ask this because, this was on the front of the edelbrock carb and the holley one takes a smaller hose size than the edelbrock did

 

this is my old carb

 

Positive Crankcase Ventilation - PCV.

No, that's not the right one on the Holley. Should go to a bigger one on the base/throttle body. Your Holley may not have it, though.

 

Most Holley's do not have a PCV vacuum port, you need a fitting to connect it to a runner on the intake manifold.

 

Or if you don't want to do that, you could just not use the PCV. Its recommended that you use it, but its not really going to hurt anything if you don't. I see in your pic that you have an Edelbrock Performer intake, which should have a threaded hole in one of the runners, to which you can hook up the PCV. If you don't run a PCV valve, though, I would reccomend using a breather cap instead of a normal oil filler cap.

 

Yeah, definitely use a PCV. It's well worth it.

The fitting you have circled goes to the distributor, for vacuum advance.

 

Did I mention my PCV port is on the back side of the carb?

No?

Didn't think so...

 

isn't this my vacuum advance?

 

.

 

My guess is that the one circled is the one for the vacuum advance. Its usually at the bottom of the carb, in the throttle plate, just where the one you circled is. as for the other larger one, im not exactly sure. Don't forget, you've got to hook up the power brake booster too. Where the PCV goes is not extremely important, pretty much any vacuum source will work. All it does is draw a vacuum on the crankcase. The vacuum advace for the distributor must be a part time vacuum source, however, IE it only draws vacuum when the accelerator is pressed. The power brake booster just needs a full time source too, unless you want to have to rev the engine up to have power brakes :P If there's nowhere on the carb to hook up the brake booster, I would use the hole in the intake runner, and just get a pipe fitting that has a hose barb on it, so yo ucan run a hose from it to the PB booster.

EDIT: If you have any extra vacuum ports on the carb, theres nothing wrong with putting caps over them.

 

Hehe, talk about a vacuum hose nightmare, take a look at my engine bay. I've still got the stock computer carb, but i no longer have the EGR, Cruise control, stock air cleaner, so I can't really just go by the vacuum routing diagram in the book. But I've taken it all apart and put it back together so many times, I can pretty much do it without thinking about it.

 

Does your carb have this vacuum port? (the one I drew the big arrow pointing to) If so, that one is for the power brakes.

 

Grr.. maybe if i attached the pic

 

Well... if it will work

EDIT: Screw it... its not attaching right...

 

Some Holley carbs have the PCV port on the back of the carb. It will be obvious which port it is becuase it's a BIG port. I have seen Holley carbs that have only one of these large ports. That's a little uncomfortable since you also need one of the large ports to feed vacuum to your power brake booster. If that's the case with your carb you should be able to find a place to screw a vacuum fitting into the intake to hook up the power brake booster line and then run the PCV line to the large port on the carb.

 

hey vettetrax the vacuum port that you have circled in green is for a vacuum guage, or an additional vacuum port. I use it for tuning with a vacuum guage. The pcv hookup should be on the passenger side on the base of the carb toward the rear if your carb has it. Do use the pcv system. It keeps the crankase from building up pressure and controls moisture build up in the engine. As RB said it is well worth it to use it.

Oh and why is that beer glass empty?

 

This one is ported vacuum(only has vacuum when the throttle is open). It's to be used for vacuum advance. All the rest of the vacuum ports are manifold vacuum(constant vacuum) and can be used for most anything. My holley has the big port, yours may not. If not you need to do as they said above and use an intake manifold source.