WHAT SHOULD A VACUUM GAUGE READ AT IDLE ?

[cudaneil]

  Hi,  Managed to get hold of a vac gauge to connect to my intake manifold.  Trying to find out why my 340 stalls at idle when

 I select drive !     If anyone can tell me what the gauge should read at idle ?


                                                                      Cudaneil

[LAA66]

 It depends on a number of things including engine condition and what cam you are using. My 340 with a mild cam is 13-14".

[rallye73]

My SRT-4 reads 19"-20" at idle.

[MEK-Dangerfield]

It definitely depends on your cam. The more radical, the lower the reading. Anything from 10 on up is my guess.   

[422STROKER]

Are all the vac lines connected?

Mine pulls 12-13" in gear.

Tom

You are looking for a steady reading either way.  Did your vac guage come with some paperwork(instructions)

[craigsmytcudas]

I think what your looking for is not the range so much as fluxation in the needle this will tell you more . pull up a chiltons manual and look at the trouble shooting pages for the vacume diagram readings .c

[Chryco Psycho]

where is the vacuum adavnce connected to

[cudaneil]

where is the vacuum adavnce connected to

            There just seems to be one vacuum hose,it goes from the holley to the distributor.


                                                                  thanks,Neil.

[cudaneil]

Are all the vac lines connected?

Mine pulls 12-13" in gear.

Tom

You are looking for a steady reading either way.  Did your vac guage come with some paperwork(instructions)

Its a borrowed vac gauge Tom,no instructions. 

So im looking for  10 to 15  at idle................and it should stay there, not drop off when put into drive ?


    Thanks for the help everyone !!!       Neil.

[Roppa440]

            There just seems to be one vacuum hose,it goes from the holley to the distributor.


                                                                  thanks,Neil.

The one from the Holley to the distributor will not be connected to manifold vacuum if it is in the stock location.

That hose is normally attatched to the passenger side of the Holley metering block (between the fuel bowl and the carb main body).

If you have any vacuum on there at idle your carb is open too far and is not actually on the idle circuits at all. Usually this happens when someone fits a bigger than stock cam and does not know how to set the carb up correctly to work with it.

Is the car an automatic?
If it has a bigger cam it could be that the torque converter now does not have enough stall speed and when you put it in gear it is pulling the rpms down too far.

[willard]

here you have a simple manual. good luck.

[Roppa440]

For that handy chart to work you need to connect to manifold vacuum and that will be a fitting right at the base of the carb.

[resq302]

Willard,

Great diagram of the vacuum gauge readings.  I have never seen that or even realized there was a method to determining all that kind of faulty areas.  Thanks for teaching me something new today!

[willard]

It seems easy while watching a chart, but diagnosing in reality is a bit difficult   

[422STROKER]

You need to connect to manifold source as mentioned and it will drop in gear but hold steady.  If all is well.  with a rumpity cam it will be less than 10", stock is near 18-20".

Tom