Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

SECONDARY FUEL CUTOFF UNDER LOAD

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omaha:
just an addition to the comments by Cliff. The "Recipes" are in Cliff's book that he wrote. I got mine at Barnes & Nobles. Guess you could get one from this site too. (from Cliff).  The black plastic thing in the fuel cavity can be thrown out with no effects that I know  of. (ok, I gotta pimp Cliffs book, you gotta get it if you aint got it already!) mine is actually starting to come apart from thumbing through it so much!
  Oh well, jus gotta say; Merry Christmas to everyone! God bless.

THEDODGEBOYS:

--- Quote from: Cliff Ruggles on December 24, 2010, 11:04:19 AM ---Waste of time to trim the splash guard to increase fuel bowl capacity. 

In any application, the fuel delivery to the bowl must keep it full at all times.

You either have insufficient fuel delivery, or the fuel inlet seat it too small, or both.  Run the larger fuel inlet seat first, and if the bowl still goes dry, increase fuel delivery to the seat.....Cliff


--- End quote ---

Thanks for the help Cliff.  The 360 is equipped with a Carter 110gph mechanical pump with 3/8 fuel line to the filter and carb.  The fuel pressue is set at 6 psi.  Under WOT, the fuel pressue never drops below 5 psi.  I did install a .145 needle/seat assembly, 6" power piston spring, and hp accelerator pump.
 
I am running a 74 primary jet with .030 primary metering rods and DA rods in the secondary on a K hanger.  I do have the rear butterflies that Pontiac used with the transition slots in them.  The truck is still doing the same thing. 

It runs fine till WOT and once you hit WOT, the fuel cuts off in the secondaries about 1-1.5 sseconds in to WOT>  I can tseem to get a handle on it.  The only other thing I can think of is that there may be a crack in the main body.

omaha:
Only things left that I can think of. 1:  secondary bleed tubes worked loose and fell out of top casting.
                                                          2:  Secondary pulloff not working correctly/or binding.
                                                            3: Secondary tubes in too far restricting fuel
                                                           4: rods not lifting far enough or need different rod or hanger combo.
                                                          5: really warped or cracked main casting/top casting.
                                                        6: Blocked passage for some reason. (gasket?)
                                                        7: blockage of secondary plates from opening (like manifold
                                                             interference with plates).
                                                            8. cam for secondary rods worn out/bad defective.

Cliff Ruggles:
I don't quite understand the 74 jet and .030" primary metering rod?  Is that a typo?

The later carb should be using a metering rod with a tapered upper section so you have control of the part throttle A/F with the APT screw.

Get rid of the slotted Pontiac plates and install solid plates.

Relocate the POE hole just under the plates, or very gently "notch" the plates so the POE holes can supply fuel under the plates.

I do agree that we may have a bigger problem here such as the parts not sealing up well, sucking air at the main fuel passages, etc. 

The Carter pump should easily be able to keep that carb full with a .145" fuel inlet seat and correct float height......Cliff

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