Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor
6 cyl draw threw turbo
hiy_po:
Looking for advice to setup my Quadrajet 17059596.
I have a 3.3litre 202 ci Inline 6 cyl Holden engine.
It kind of looks like a smaller version of your Chev inline 6's.
It runs a Rajay Turbo draw threw turbo system. I have a Quadrajet 17059596 It is modified to reference the power piston from after the turbo and has a one way so dos not blow into the power piston.
Some engine specs - After market Alloy head 12 port 1.5 ex 1.7 in 70cc chamber
.462 valve lift LC 112 with a 1.65:1 roller rocker
7cc dish tops 7.3:1 c/r
Ignition is via an ECU fully adjustable with MSD 6AL igniter and MSD coil Blaster 3
5 speed manual 3.08:1 LSD diff
My progress so far
FIRST Carb (Stage Two Ver 3)
________________________
Idle Down tibes 1.6mm 0.064' #52 top 1.2mm 0.046' #56 bottom
Idle Down-Channel Restriction 1.59mm 0.062' #52
Idle Discharge tube 3mm 0.118' #32
Upper Idle Air-Bleed 0.4mm 0.18' (Air horn)
Upper Idle Air-Bleed 1.78mm 0.070' #50
Lower Idle Air-Bleed 2.2mm 0.087' #44
Idle Air By Pass throtle plate outlet 2mm 0.079' #47
Main Air-Bleed Airhorn 2.3mm 0.090" #43
Primary Jet 0.073
Primary Rod o.048
Custom: / (2-5) / 0.900' spring
ATP 2 turns up.
Secondary Metering Rods 0.044 inch tip “DA” code
Secondary hanger bracket B
Measurements in mm then thou then Index size if known.
My progress so far
FIRST Carb (Stage Two Ver 3)
________________________
Idle Down tibes 1.6mm 0.064' #52 top 1.2mm 0.046' #56 bottom
Idle Down-Channel Restriction 1.59mm 0.062' #52
Idle Discharge tube 3mm 0.118' #32
Upper Idle Air-Bleed 0.4mm 0.18' (Air horn)
Upper Idle Air-Bleed 1.78mm 0.070' #50
Lower Idle Air-Bleed 2.2mm 0.087' #44
Idle Air By Pass throtle plate outlet 2mm 0.079' #47
Main Air-Bleed Airhorn 2.3mm 0.090" #43
Primary Jet 0.073
Primary Rod o.048
Custom: / (2-5) / 0.900' spring
ATP 2 turns up.
Secondary Metering Rods 0.044 inch tip
Secondary hanger bracket B
Measurements in mm then thou then Index size if known.
hiy_po:
It runs but Idle is lean, Idle mix screws are 3.5 turns out and carb does respond to them, Touch throttle and goes rich.
Idle stop screw is about 2 and a half turns out.
0.067" #51 I think is what will work for IDCRs
I have two Upper Idle Air Bleeds 1) from throttle bore to Idle down channel on a downward slope.
2) In Air horn see attached pic.
Should I block the top ones?
I would need to know the specs in thousands of the following items.
The idle tubes (bottom or restriction at the end of them)? - 0.046' #56 bottom
Lower idle airbleeds? - Lower Idle Air-Bleed 0.087" #44
Upper idle airbleeds and location? (There should only be one pair either just above the DCR's or in the airhorn, not both) - I have both see above Upper Idle Air-Bleed 0.18' (Air horn)
Upper Idle Air-Bleed 0.070' #50 IDC.
Main airbleeds in the main casting? - unkown look small in a brass bleed.
Main airbleeds in the airhorn? - 0.090" #43
if I am doing something that isnt the best, would like to hear about it.
Things that matter, Engine is low compression and is 10/12 Hg at Idle.
Is a 3.3 inline 6 cyl.
My aim. Get good fuel economy for long trips but have 12s AFR at WOT with Boost.
My theory
Need large jets and orifices to counter low vacuum, but 6cyl doesnt need the same amount of fuel as a V8 so highly sensitive but low volume supply.
Things I dont know and would like to,
The Idle tubes, should I be opening the bottoms of the idle tubes and leaving top of tube standard?
Will opening the Air-Bleed to the main circuit in the venturi have more effect than opening the one in the air-horn?
hiy_po:
My settings mm removed
Idle Down tibes 0.064' #52 top 0.046' #56 bottom
Idle Down-Channel Restriction 0.062' #52
Idle Discharge tube 0.118' #32
Upper Idle Air-Bleed 0.18' (Air horn)
Upper Idle Air-Bleed 0.070' #50
Lower Idle Air-Bleed 0.087' #44
Idle Air By Pass throtle plate outlet 0.079' #47
Main Air-Bleed Airhorn 0.090" #43
Primary Jet 0.073
Primary Rod o.048
Custom: / (2-5) / 0.900' spring
ATP 2 turns up.
Secondary Metering Rods DA 0.044 inch tip
Secondary hanger bracket B
Needle seat 0.130
hiy_po:
Main Air Bleeds (In the main casting) - 0.025"
Drilled my IDCR - 0.067 #51
Measured the Main Air Bleeds in the Main casting while I had top off.I have a 0.026 Bit so am thinking will use it while apart. So upgrade that size -
Main Air Bleeds (In the main casting) - 0.026
hiy_po:
Just went for test drive, mains are still rich and Idle mixture screws are 3 1/4 turns out, Throttle stop screw is about 2 turns out Idle is around 950 rpm and close to stoich maybe 14.2:1 AFR.
I am noticing I dont seem to get a leaner cruise with some manifold vacuum, seems not much if any difference between driving at 4Hg and 1psi Thinking need to hit the main air bleed in the main body with the next drill size up.
Navigation
[0] Message Index
[#] Next page
Go to full version