Holley Carb Question

[cwestra]

On Holley carbs does float level affect idle speed?

[Supercuda]

Ony if it's really, really off. It will affect idle quality, though.

[brads70]

Can't say I have ever experianced that with the float level? what's yours doing? idle to high?

[cwestra]

Can't say I have ever experianced that with the float level? what's yours doing? idle to high?

Yea.  Can't get it to idle below 1100 even with fast idle and idle screws backed off. 

[brads70]

Check for a vacuum leak? When I went to put my Demon carb ( Holley based) on my new intake I noticed the carb rocked ever so slightly . I had to used a die grinder to clear some of the intake casting away from the secondary linkages.
Another thought....is your throttle linkage holding it open? Take off the linkage to see if it closes the butterflies any more?

[72rtchallenger]

Check for a vacuum leak? When I went to put my Demon carb ( Holley based) on my new intake I noticed the carb rocked ever so slightly . I had to used a die grinder to clear some of the intake casting away from the secondary linkages.
Another thought....is your throttle linkage holding it open? Take off the linkage to see if it closes the butterflies any more?

[brads70]

Is this a new carb? I ask as I've seen people, drill out the holes in the butterflies to adjust the idle...?

[71chally416]

Make sure the secondaries aren't too far open. That's tripped me up more than once. 

[72cudamaan]

Wonder if the throttle blades ( butterflies) are rubbing on the intake or spacer?

[cwestra]

Thanks for the feedback everyone.  This is a problem I've been dealing with for a while now and I have tried several things in my attempts to identify what is going on.  No luck so far.


brads70:

I have checked for vacuum leaks at all known areas using Gumout spray.  Everything appears good.  And I have checked and adjusted the secondary linkages several times and am confident they are closing all the way.  The carbs are original Holleys.  I do see holes in the butterfly plates but they do not appear to have been drilled.  What size should they be?


71chally416:

Yes, I have removed the linkages and held the throttle closed and then slipped the linkages back in.  They fall right into the holes.


72cudamaan:

The throttle plates do not appear to be catching on anything but I can look deeper into that to be sure.  There is one thing that seems odd.  When I go to start the car after it has cooled, I first step on the accelerator pedal to close the choke plate before starting.  When I do this I can feel (and hear) the throttle plates break loose from the bores indicating that the bores have contracted around the plates enough to stick them during cooling.  I'm not sure if this has anything to do with the problem I'm experiencing but it's seems a bit odd.

I checked the fast idle cam and it is not engaged.

I am wondering if there could possibly be a leak between the intake manifold and head causing it?

[72cudamaan]

I would think that leak would've shown up with the spray. Have you tried using a vacuum gauge?

[brads70]

Is this a six pack set up? or single 4 barrel?

[cwestra]

Is this a six pack set up? or single 4 barrel?

Factory 6-Pak for small block.

[MEK-Dangerfield]

This is interesting. I'll assume the secondary carbs are vacuum operated here. What happens when you try to put the car in gear? Usually with a vacuum leak, it will want to stall unless you give it gas. Are you certain you are idling at 1100RPM? The original Rally gauge tachs tend to read higher than reality unless they have been rebuilt or re-calibrated. If you have an aftermarket tach, then I'm sure it's accurate.

[brads70]

Hummm good point Mike!
Are the carbs new? Just wondering if the throttle shafts are worn , letting air by?