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It's been a LONG time since I had to do any carb tuning.  My last carbed motor was a 440 with dome top pistons, a hot cam and a holley 1150CFM double pumper... back in 1979.

Now, as of a few months ago, I have a Holley vac secondary 600 on my 360 RC.  I found I still remembered how to set the mixture by ear, and it runs pretty good now (yes, I confirmed with a vacuum gauge once I cleaned out the garage and found it).  It runs *really* good at mid and WO throttle  8)

But, starting from a dead stop there is some pretty serious hesitation and when cool it sometimes takes some fancy footwork to keep it from stalling.  If my memory is working, that's something to do with the accelerator squirter, but I can't remember what, exactly. 

Is the engine hesitating because the throttle opens up and there is too much air and not enough vacuum to suck fuel from the jets (so I need more fuel from the initial squirt of the accelerator pump)?  Or is there too much gas from the accelerator pump, causing a brief flooding situation?

I'm trying to figure out which way to adjust the pump arm and avoid too many tweak-drive-tweak replays  Any ideas, carb guys?
 

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You need either bigger nozzle or cam that gives more shot sooner.
 

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Don't go changing the squirters yet. Is your squirter lever adjusted properly? i.e. does it begin to squirt with the slightest movement of the throttle?

madurobob said:
Is the engine hesitating because the throttle opens up and there is too much air and not enough vacuum to suck fuel from the jets (so I need more fuel from the initial squirt of the accelerator pump)? Or is there too much gas from the accelerator pump, causing a brief flooding situation?
Your theory of how it functions is correct (not enough vacuum to pull fuel through the jets) at least to describe why we need an accelerator pump, but it could be either causing your problem.

Go to Holley's website and download an owners manual. If you can't find the exact carb you have, just find one for any vacuum secondary carb (like a street avenger) and you can follow the instructions on squirter setup from there.

I have a Demon (similar to Holley) and I had a mild off-idle hesitation, a lighter vacuum secondary spring solved that. I would still look into the squirter first however.
 
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