Holley transfer slots

[BSB67]

This weekend I set my primary throttle blades to expose only .020" of the transfer slots.  I closed the secondary throttle blades and just barely cracked them open from their seated position.  I picked up one of those secondary idle screw brackets and mounted it as well.  This way once I get the car running I can set my idle using the secondary idle screw from the topside and leave the primaries alone.  I do plan on checking the timing again as well and seeing if there is any change at idle while the car is in gear and put into park.  I hope to get all this done Halloween weekend.  Thanks for your input. 

Good grief.  I'm at a complete loss on what to say.

[Godsmack635]

Only problem doing it that way, now you wont know how much you are opening the secondaries... too much and you will get a bogwhen they open and have more idle issues. Thats why i said to open both to the max safe limit of .020-.030 and put the carb on. Start it up and see how it idles. If the rpm is still too low like that, then you will need to drill the plates. If the idle is too high, then you can start backing then down.

I misunderstood.  The carb is still off on my workbench so I can try it this way.  Open both to .020" and see where I'm at.  If my idle is high, would I adjust both primary and secondary to idle down the same amount, or do I still leave the primary throttle blade where it is and only use the secondary throttle blades to decrease my idle?

[c00nhunterjoe]

Only problem doing it that way, now you wont know how much you are opening the secondaries... too much and you will get a bogwhen they open and have more idle issues. Thats why i said to open both to the max safe limit of .020-.030 and put the carb on. Start it up and see how it idles. If the rpm is still too low like that, then you will need to drill the plates. If the idle is too high, then you can start backing then down.

I misunderstood.  The carb is still off on my workbench so I can try it this way.  Open both to .020" and see where I'm at.  If my idle is high, would I adjust both primary and secondary to idle down the same amount, or do I still leave the primary throttle blade where it is and only use the secondary throttle blades to decrease my idle?

What you are doing is basicly a test to see if you need to drill the throttle plate. What you are doing is opening both sets of blades to the maximum you can without overexposing the transfer slots. You bolt the carb on and dont touch either sets of blades. Now start the engine. If the idle is still to low then you now know you are out of adjustment and will have to drill the butterfly to allow more air in. IF the engine is idling too high, then you can close the secondaries until the desired idle speed is met.
  All that my method is doing is taking alot of the trial and error out opening the blades a little at a time, to only find that you dont have enough adjustment and need to drill.
   You still need to verify that the timing is rock solid and not moving from park to drive. If it is, it throws everything off.

[Godsmack635]

Ok got it.  I will post my results as soon as I can get a few hours this coming weekend and see where I'm at!   

[500Jon]

WoW this is interesting stuff indeed!
Got a QF with similar issues here.
looking for 800 in neutral and 600 in drive?
Is this a reasonable request???
440 SIX PACK with Auto...
5J

[1974dodgecharger]

your going through what I went through   

Fun aint it 

Drilled my primary 1/8inch to even get my car to idle nicely.  Due to cam 509 and old 80s carb with no IAB now they call it? 

[Paul G]

I am playing with two Holley carbs right now, a 670 SA and a 3310 750 converted to 4150. Both vacuum secondary carbs so a little different than what you are doing but adjusting idle should be very similar. Being old used CL carbs there is no way of knowing how worn out the carb really is, which might effect the factory settings for idle slot adjustment.

What worked for me with both carbs was setting the secondary transfer slot square like it is supposed to be. Then when trying to adjust the idle mix and idle speed on the primary, and it would not idle on the idle circuit, meaning the primary throttle plate was too far open and idling on the main circuit, I would open the secondary butterfly just a little at a time, allowing more air and fuel in from the secondary, which let me close the primary down enough to get back on the idle circuit and control the mix from the primary. Make sense? Very small moves on the secondary side, allowing the engine to get more idle air and fuel from the secondary helped.  

Now what I have found is, if I take a rag and completely cover the primary side with the engine running it will die, which is what I would expect. Same goes for the secondary side, choke it off completely with a rag and the engine will die. Dont know if that is normal? But the car runs well like this.