1500 vacuum question

[JPSmit]

the vacuum hose originates at the carb - where does it end?

 

[tosoutherncars]

vacuum advance for the dizzy?

 

[Morris]

It tees and one end goes to the dizzy, the other the EGR valve. Somewhere there is a flame arrester in there.

 

[JPSmit]

of course you are right - dizzy - egr valve?

 

[tweety]

new b question... What's a dizzy?

 

[jlaird]

distributor

well maybe a young blonde.

 

[tweety]

Ok, I feel like the blond now

 

[JPSmit]

but I'm still not sure what the line attaches to - egr valve? where is that?

 

[Morris]

Are you keeping your EGR system functional? For some reason, I thought your eliminating all your pollution equipment.

If you are keeping your EGR functional, the vacuum line that attaches right above the throttle should tee with one side of the tee running to the EGR valve which on your car is on the exhaust manifold just under the intake manifold toward the front side of the car.

If you are not keeping the EGR functional, simply run the vacuum line to the dizzy with no tee.

My car had a "flame arrestor" fitted to the vacuum line. It's a small metal cylinder that looks kinda like a fuel filter. It's pretty important to have on there because it will keep backfires from melting your dizzy diaphragm.

 

[JPSmit]

Not keeping the EGR functional - BUT I still don't know what the OTHER end attaches to - the dizzy part I got down pat, surely it goes somewhere from there?

 

[jlaird]

Goes somewhere from where. It only needs to run from the output on the carb or manifold to the Dizzy. Thats all folks.

 

[Morris]

Without the EGR, it's a straight shoot from the dizzy to the carb.

 

[bthompson]

Hi, JP...I've been through it all before trying to get Nigel's Z-S sorted out. His PO made a right mess of it, taking the "if it doesn't work just cap it off" approach.
Here's where everything goes, if you're standing on the driver's side looking across the engine at the carb:
The hose next to the air bleed adjuster, on the upper left side, is the restricted-connection hose to the valve cover. That hose tees off to the top-center fitting of the charcoal canister, also restricted.
The hose on the top side center runs down to the flame trap, then to the egr valve. It tees at the valve, and runs to the little plunger valve on the choke.
The hose on the left side bottom runs to the flame trap, then to the dizzy, IF your distributor has a ported vacuum advance. If not, cap it off.
The hose on the rear right, over the gas line, runs to one of the top side connections on the charcoal canister.
The tap on the intake manifold goes to the runon valve, then to the bottom connection on the charcoal canister. IF your distributor has manifold vacuum advance, there's a tee at the manifold: one side to the runon valve, the other side to the dizzy.
If you don't have the flame traps you don't need them. If your egr valve is rusted solid, or you're gonna run desmogged, you can cap off that stub at the carb (top center).
Hope that helps!

 

[Morris]

Wow! Great reply Bill! I did not realize the '76 set up is so much different than the '79.

 

[JPSmit]

Bill, thanks for the explanation it was a little hard to visualize because all the smog stuff is off the car.

here is a photo - just my phone - sorry.

If you look carefully, there is a slotted screw just "below" the bell. It looks to me as though it has been capped with this screw. - is this where the vacuum line goes?

On the left side of the carb using the picture as a reference, (out of sight in this pic) there is a slotted screw head right next to the hose that comes from the valve cover - that's the air adjustment I presume.

Also, in the bottom right of this picture is a large bolt with a hole in it. I know the flange broke off. I should just cap this - yes?

thanks again for all your help

JP

 

[bthompson]

Hey, JP...you're right; the slotted screw under the bell is where "Someone" plugged off the EGR vacuum line. I would get a little rubber vacuum cap from the auto parts store and cap it properly. (The old screw-in-the-hose trick might work for Holleys and Quadrajets, but Zenith-Strombergs are just too sensitive to vacuum leaks to risk air getting past the screw threads.)

The big bolt in the middle of the intake manifold is where the metal pipe from the EGR valve is supposed to go; since yours is gone, you don't have to worry about any EGR vacuum lines. The other big bolt with the hole is where the vacuum manifold port is, that's the line that goes to the runon valve. I'll bet you don't have your runon valve, so don't worry about it...without the air pump and EGR setup, you shouldn't have to worry about running on anyway. You can just cap that off. (It also makes a handy place to attach a vacuum gauge!)

The air adjustment screw is what looks like a white plastic bolt with a slotted screw in the middle of it. It is used to bypass a tiny amount of air past the throttle butterfly for fine-tuning the NO for emissions. The white plastic bolt is the "course" adjustment; the screw is the "fine" adjustment. Without the air pump, catalyst, and EGR, it's really too fine an adjustment to do any good anyway; might as well close it off. Turn the bolt in, then turn the screw in, until they just bottom out. That'll take that whole system out of the equasion and make tuning the thing easier later. (You're welcome :wink: )

While you're on that side of the carb, there's a little pyramid-shaped pod under the vacuum line that runs to the valve cover. It's held on with Phillips screws, and there's a little slotted screw in the middle of it. That's the decel valve. When you rev the engine and snap the throttle shut, the smog equipment makes the engine sputter and pop on deceleration. Without smog equipment, you shouldn't need that either! You shut it off by screwing it OUT, the opposite of what you'd think. Take that out of the system, too, by turning it out all the way. If you find the engine fluffering a little when you blip the throttle, you can screw it in a turn at a time and bring it back in the loop.

The vacuum line next to the right of that decel valve is the one that goes to the distributor.

 

[tosoutherncars]

(...) If you find the engine *fluffering* a little when you blip the throttle, you can screw it in a turn at a time and bring it back in the loop.

Fluffering! I'm going to have to Google that one... hehehe Must be a technical term.

 

[JPSmit]

thanks Bill - I'll check it out in a minute. Didn't realize fluffering was a Midget malady also. I thought it was only me and only when I ate cabbage :blush:

 

[JPSmit]

Bill, I adjusted the white plastic & screw. opened the decel valve screw. I still don't know where the hose goes. your last comment -

"the vacuum line next to the right of that decel valve is the one that goes to the distributor." confuses me.

to the right of the decel valve all I really see is the manifold. that pyramid pod seems to not have any openings. There is one to the left and one by the hose to the valve cover but frankly neither of those seem to be vacuum openings -

Help!

thanks

 

[tosoutherncars]

JP decides to fit an SU in 10.... 9.... 8.... :wink: