Nekrostatic

Just picked up a 76 98 Regency. The old owner (or one of them?) swapped out the Rochester for a nice Edelbrock, and in the process, got rid of most of the vacuum lines. Anyone have a good diagram? Vacuum routing confuses the hell outta me. I WAS winging it with a diagram I found online, and then I found out that diagram was for a 350.

Nekrostatic

The carburetor is an Edelbrock 1400. I'm having trouble determining which port is which in following the diagram I got from Autozone. I found the one that is manifold vacuum, but the stock Rochester seems to have 3 ports, while the Edelbrock only seems to have 2? Also, my engine doesn't seem to have the thermal control valve located by the thermostat spout? I'm so confused hahaha.

joe_padavano

Well, first, the diagram (that didn't make it into your post) assumes the factory carb. It's unlikely the aftermarket carb has all the same ports. Second, is the intake even stock? Post a photo of the engine. Third, spend the money and buy a factory Chassis Service Manual, which as all the correct factory info. You'll want this book if you ever do any real work on this car.

Nekrostatic

Sorry, was gonna put up pictures with the post but I seem to be having problems putting up images on this computer. I'll put some up on my day off on Friday. It definitely does not have the same ports. but I'm having trouble determining which port is supposed to be which. The manifold does definitely look like the stock manifold I've seen in every other image though. I plan on picking up a service manual this week but I'm right at the tail end of my pay weeks so I'm kinda flat broke until then.

oldcutlass

On your Edelbrock carb the 2 small ports on the front are, passenger side is ported vacuum, drivers side is manifold. The larger ports front and back are both manifold vacuum. The PCV needs to be hooked to the front large port.

Nekrostatic

Yeah, I was able to pull the owner's manual for the carb up in my store (work at a True Value parts store). While the manifold vacuum one makes sense with the Olds diagram, I didn't know if the other side was ported or something else. And then the Edelbrock is missing the valve-lookin' thing coming off of the front of the Rochester. Would I just tap that into the ported lines?

joe_padavano

It's available on-line

Nekrostatic

Oh, righteous, thanks!

oldcutlass

Valve looking thing...?

Nekrostatic

Sorry, braindead today. Vacuum diaphragm.

oldcutlass

For the power brakes? That would be connected to the rear port. If you read the carb instructions it will tell you how to open that up, just buy a nipple.

joe_padavano

Are you talking about the choke pull-off and vacuum break diaphragms?

Nekrostatic

YES! The diaphram on the side. Towards the front of the engine.

oldcutlass

I thought you said you have an Edelbrock carb?

Nekrostatic

I do. And it doesn't have the vacuum brake diaphragm. So I don't know where to run those lines to.

oldcutlass

What manifold are you using for this carb? For the power brakes, as I mentioned above there is a port on the bottom back center of the carb that you will need to add a nipple to. See the instructions link, there is an embedded picture of it on top right of the picture on the first page.
http://static.summitracing.com/globa...Carburetor.pdf

joe_padavano

One, it's a vacuum BREAK, not brake. The latter stops your car (and will further cause confusion here with people who think you are talking about the vacuum brake booster on the firewall.)

Two, the vacuum BREAK is part of the original Qjet carb and is not used on the Ebrock carb. The hose goes directly from the vacuum diaphragm to a port on the Qjet. That hose shouldn't even exist anymore. Ignore it.

Also, stop trying to use a factory vacuum diagram to connect your aftermarket carb. You can't. The factory diagram is for the factory carb, period. The aftermarket carb is different and may or may not have all the connections you need. This is the fundamental problem with an aftermarket carb, especially on a mid-70s car with lots of unique emissions control connections. Either understand how your new carb works and connect it as needed or go back to the factory carb and connect it per the diagram.

Arrowstorm

Once you put an aftermarket carb on your engine, pretty much all your factory vacuum diagrams go out the window. If you're not familiar with what is controlled by vacuum and where it needs to come from, you have to understand that first, and then you'll feel a little more comfortable not "going by the book".

MDchanic

Also, doesn't the '76 QuadraJet have an additional EGR port?

- Eric

joe_padavano

I assume it would need a timed port for EGR activation.