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Carburetor - Stalling? Adjustment needed?

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  • Carburetor - Stalling? Adjustment needed?

    I got the Firebird in a condition where it was safe to drive it on the street, so long as it wasn't raining (no windhsield wipers) and not at night (one headlight and no tail lights, brake lights and turn signals work though) so I put a few miles on her this weekend. Something I noticed though was that if I stomp the gas, the car tries to stall out. I have to let off to about 3/4 throttle for the engine to kick in again. Don't know what happens if I ease into it, and I may have been at low RPMs.

    I held it down for about 4 seconds (bad idea?) to see if the engine would eventually roar to life but it didn't happen. My RPM may have been too low though. I'm used to the sound of my 4 cylinder Sentra, and I tried to keep the 'sound' of the V8 in a lower RPM range, but I may have overcompensated. And I don't have a tach in it (might look into one though) and I've never driven a V8 often.

    So... could an improperly tuned carburetor setup do it? The car has a Tri-Power intake which I've been told is notoriously hard to tune properly, but I think only the center carb is adjustable. The front and rear carbs are either 'on' or 'off' and they all dump fuel into a common chamber in the manifold, its not like the front and rear carbs provide for 2 cylinders each and the middle does 4, they all service all cylinders. I could be mistaken though. I was under the impression that an untuned multicarb setup would cause a delay before acceleration, not an outright refusal to do so.

    Or, could it be caused by low RPM? I know if I stomp the gas in my Sentra at 40 MPH in 6th gear is just kinda goes uuuuhhhhhhh clop clop clop or something.

    2003 Nissan Sentra SE-R Spec-V

    PROJECT: Firebird '68 Firebird Convertible // 455 Engine // 389 Tri-Power Intake // 4 Speed Manual Trans

  • #2
    You are asking to drag up some old memories here. I'm thinking it's a blown power valve in the center carb.

    It could be the secondaries (front and rear carb) opening and bogging. I'm very familiar with the Dodge 6 pack but not with the Pontiac tri power. One of the old tricks was you could put a screw with a nut on the back in the slot in the linkage that shuts off the secondaries to force them to open before the vacuum will open them. There should be something like that on these carbs. See if someone put a screw in it and take it out. At least until you get to the point of fine tuning it.

    If it has been a long time, I would suggest rebuilding them. It's not hard.
    2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning

    1995 Z28, many mods, SOLD

    A proud member of the "F-Body Dirty Dozen"

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    • #3
      Great trick used it my self...
      your racing 16 year old Camaro Berlinetta Digital Camaro 202 heads 4 barrel and soon to be headers with 4 inch running back

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