DBM_NJ

Symptoms: (1973 350c.i. L82) I disconnected the vacuum line (and plugged it) from the distributor Vacuum Advance and adjusted the accelerator linkage screw to get to 850RPM, then I adjusted the air/fuel mixture screws to get the peak RPMs at that speed. When I reconnect the vacuum line (manifold vacuum) to the Vacuum Advance the RPMs increase to about 1200 RPM with the timing also advancing to about twice the original setting (10BTC). At this point I can't get the RPMs to drop below 1200. I have unscrewed the accelerator linkage screw to where it no longer makes contact with the linkage, I did the same with the choke idle adjustment screw - but neither has any effect on the RPMs.
Any suggestions would be appreciated.

mr303

The cable from the gas pedal may be binding, disconnect it and see if you can drop the idle. With the idle adjust screw all the way out your car should not idle at all, the screw needs to hold the butterfly's open to even idle the engine

DBM_NJ

Been there, done that, no difference.....

mr303

OK! some thing has to be hanging up somewhere, you may have to remove the carb and inspect from all angles. The choke set up on these is a little complex with fast idle cams and choke vacuum etc, but I guess you have looked at all this? The next port of call would be the butterfly's them selves or the linkage between the primaries and secondaries. Sorry I can't be of more help but a problem like this really is a visual thing, hope you can work it out.

Bob Onit

Try the ported vacuum and see if it drops down
This will eliminate any carb issues

I had a similar problem
My '73 refuses to run on manifold vacuum

LYLE

Have you tried unhooking the choke rod from the spring. On the side the choke is the pin on the butterfly rod can hang up.

694speed350

With manifod vacuum the vacuum can advances the timing which in turn advances idle speed. the idle adjustment should be adjusted to correct idle speed. in my opinion if you have a later model with emission controlls you may not be able to adjust the carb to get correct idle speed or mixture.

DBM_NJ

I don't seem to have a ported vacuum tube - There are two vacuum connections above the throttle plate but they both seem to have full vacuum at all times. I have disconnected the Vacuum Advance Soleniod (TCS System) since it wasn't working properly and it was supposed to control the vacuum (no vacuum at idle) to the vacuum advance.

Bob Onit

Sorry if I missed it but I dont see where you stated which carb you are running

Whoops........ the title says QJ

DBM_NJ

I have an inoperative Vacuum Advance Solenoid (TCS System) that I disconnected - could this be restricting the idle adjustment?

DBM_NJ

Rochester Quadrajet Model# 7043213 FV

DBM_NJ

I am not sure I understand - what do you mean by "butterfly rod"? I will need to study the choke descripion in my manual a bit more.

Bob Onit

The ported source is on the drivers side at the bottom of the float bowl
There should be no vacuum until you crack the throttle.

DBM_NJ

Thanks - I'll look there tomorrow.

Bob Onit

Heres a shot of the ported source
I am no expert but all of the Qjets I have run had no vaccum until the throttle was opened.

DBM_NJ

[QUOTE=Bob Onit]Heres a shot of the ported source
I am no expert but all of the Qjets I have run had no vaccum until the throttle was opened.[QUOTE]

Here is a photo of my setup - it seems that the vacuum line you pointed to in your picture is connected to something else on my car - I will investigate further tomorrow.

Bob Onit

Thats the ported source
Same as I have mine setup
If you dont have a vacuum gauge you can borrow a vaccum pump (which has a gauge on it) from Auto Zone and test both the manifold and ported vacuum.


EDIT
Is the hose with the white stripe coming from the Vacuum can?
Also you have no linkage to your accelerator pump
EDIT Again... I see the linkage to the pump
I had to zoom in.... sorry

DBM_NJ

1. I got a vacuum gauge recently and will test the ports.
2. Yes, the white stripe hose runs to my Vacuum Advance can.
3. What do you think the hose that connects under the float bowl on my engine runs to?? Something else affected by ported vacuum?
3. The accelerator pump linkage is connected but can't be seen from this view - and it squirts a good volume of gasoline.

Bob Onit

Yours is setup the opposite of mine


Test the ports with the vacuum gauge and post the
results.

I am actually starting to doubt myself as to which port is which, as manifold vacuuum should be below the float bowl and ported should be above it
I had this discussion with BarryK a few weeks ago


Run the test and it will tell you which is which.

ps: Is this a standard or auto trans?

BigBlockk

You are set up on manifold vacuum. You may want to look at the fast idle cam. It may be sticking and holding the idle speed up.

BigBlockk

Later.....