Nozzle drip on ported vac

[blazer74]

Hello,      Carb 17056228      EDL wood spacer
     036 IT     047 ICR     72/44cliffs      086 bypass air
      268H Cam 218@50   454   110/106   15- Vac
      355 SBC   Vortec Heads    9:1 Comp  Headers/Dual Exh
       Carb gone thru with cliffs parts. APT 4 and mix 3 turns.

I have a small bit of nozzle drip when using ported vac advance.
Goes away with full manifold vac and 1/2 turn less on idle screw for
650 rpm.
Would adding some more bypass air help with ITubes aready @ 036?
Everything else is good, throttle blades tight.

1974 K5 Blazer
Thanks.   Craig


               

[blazer74]

Also 10 Deg initial timing

[blazer74]

One more thing to add if I pull the vac line off the choke break idle rpm increases making me
Think more bypass air?

[Cliff Ruggles]

Pull a vacuum line as a test, then reduce the throttle angle and re-adjust the mixture screws.  If you still have control with the mixture screws, and no nozzle drip, add some bypass air.....Cliff

[blazer74]

Ok will do thanks Cliff.

[blazer74]

Ok, got a good weather day and the time to try the procedure recommended by Cliff.

Fully warmed, choke completely open choke I pulled the vaccum line off the choke break, rpm increase of approx 150+ rpm. Backed the idle srew out 1/2+ to bring idle back down to 650/700 rpm. Still have full control of mix screws and can kill the engine by turning all the way in just as was before. Mix at 3 turns out, starts to drop rpm/vac at 2 turns out and dies when all the way in either side. No change from before with vac line connected for mixture.

So the question is how much more bypass air, currently at .086. Next drill bit sizes are .089  .093  .098?
I do have another base plate from a 17057204 carb with .110 bypass air. Current carb Im using  is 17056228.

I could try it a see how it works or what do you suggest start with next size of .089 and see how it does.


Mix 3 turns,  Neutral 16+ vac 800 rpm.  Drive 15+ vac  650/700 rpm.    Neutral to drive is about  a 100 rpm drop.

I also noticed that in neutral with the idle adjusted down  to 650/700 rpm with the mix screws out past 4 turns the rpm will drop off a bit, but in drive with the idle adjusted the same it does not. Make sense?
 

Thanks Again Craig.

[Cliff Ruggles]

I'd go to .098" and test again....Cliff

[blazer74]

Hey Cliff you did mean .098 and not .089, just to make sure.  thanks Craig

[blazer74]

Hello, haven't opened up the bypass air yet but I am dealing with a different issue as of late.

Have a hesitation stumble on light accelleration not initial accelleration under 3000 rpm  just briefly then clears up after letting off accellerator pedal. It recovers on its own. This is generally on a hot engine after sitting at say sonics for about 20 minutes. Doesnt always do it either.
Sometimes I can go like all and other times it will stumble go flat briefly.
Adjusting APT does not help. Mixture doesn't help I can sometimes get this also WOT over 4000 rpm, but again not always.

Fuel pressure fluxuates from 3-6 psi at idle.  My float is set just under 1/4 at 3/8.

Not really sure where to go with this one other than raising float a little or possible heat soak issue but starts with just a touch of the throttle while cranking and idles fine. Thats after sitting about 20 minutes.  I cured a hot start flooding problem not too long ago with an edl street pump.

Thanks for any suggestions. Craig.

[blazer74]

Bye the way I have had the APT down all the way down progessivly  from 4 turns up  and have no problem running cruise speed trying to cure this problem. currently at 1 turn up. Fine just off idle also.

Possible igniton problem?

Thanks again.