What would cause car to not stay idling

[B3422w5]

850 race brawler, even in park, I let off the gas, idle comes down within just a few seconds, gets so low have to give it more gas to keep idling.
little while back I found front bowl needed float level lowered, adjusted it, idle seemed to be fine afterwords, even in gear, like it fixed the issue completely.
next time I drive it( yesterday) I notice it’s back to doing what it originally did, got back home with it, didn’t get chance to check float level again, I assume it’s Ok.
not sure what is going on..
street strip motor, doesnt seem to have a vacuum leak, sprayed brake clean around a while back just to make sure, even before this issue.
fuel pressure about 6.5, sizable cam, but car idled fine with same cam in a smaller, much milder motor.
anything I should look for?
have not taken carb off or apart yet. I do have another carb I could try, it’s been sitting a while, but it’s an optionif need be. Probably would need a kit

 

[12many]

I like starting with one area and verifying it’s good. Never hurts to remove the carb, the bowls and metering blocks, carb cleaner flush and reverse flush along with compressed air the same both directions every orifice etc. Only time I’ve had something like you describe with any carb (cars in the past but primarily dirt bikes) was fixed by a general power flushing as mentioned. And problem solved. You gotta check and maybe readjust the pump arms after all buttoned up is all, put idle screws back where they were etc. Filter before or after regulator?

 

[B3422w5]

I like starting with one area and verifying it’s good. Never hurts to remove the carb, the bowls and metering blocks, carb cleaner flush and reverse flush along with compressed air the same both directions every orifice etc. Only time I’ve had something like you describe with any carb (cars in the past but primarily dirt bikes) was fixed by a general power flushing as mentioned. And problem solved. You gotta check and maybe readjust the pump arms after all buttoned up is all, put idle screws back where they were etc. Filter before or after regulator?

Before regulator.
car runs fine and crisp at full throttle, just idle is an issue.

 

[Jadaharabi]

Vacuum leak under the intake.

 

[12many]

Before regulator.
car runs fine and crisp at full throttle, just idle is an issue.

You might could check the turns out of idle screws, then remove and shoot some carb spray in each. But what I’d do at minimum is leave the carb on, measure what clearance I have on front/rear pump arms, pull the bowls and blocks then do the carb spray and compressed air deal to all the orifices, air bleeds etc in the idle circuit. Reassemble and check/reset the pump arms clearance and set idle screws to what they were and see what happens go from there. Might solve it, might be something else.

 

[B3422w5]

You might could check the turns out of idle screws, then remove and shoot some carb spray in each. But what I’d do at minimum is leave the carb on, measure what clearance I have on front/rear pump arms, pull the bowls and blocks then do the carb spray and compressed air deal to all the orifices, air bleeds etc in the idle circuit. Reassemble and check/reset the pump arms clearance and set idle screws to what they were and see what happens go from there. Might solve it, might be something else.

I will do exactly that. Sounds easy enough and worth a try. Thanks!

 

[RustyRatRod]

Does it have a choke? I'm bettin no, so you caint use that, but try starting it and covering the primaries a little acting like a choke is on some. If it idles then you just verified a vacuum leak.

 

[Jadaharabi]

Check your manifold bolts. Put a wrench on them and give them a pull.

 

[Snake]

pull your distributor check each post I had a similar problem like yours I found each post blacken cleaned and idles great once again.

 

[Oldmanmopar]

Make sure you square the primaries and idle off the secondaries. The primaries should never go past square. The main reason for the secondary idle adjustment. If you cannot idle off the secondaries square the primaries and drill four 1/8 holes as seen in the last picture