Q-jet on 455 runs terrible!

Discussion in 'The Venerable Q-Jet' started by LDPosse, Jun 15, 2004.

  1. LDPosse

    LDPosse Well-Known Member

    GS464 -

    I've made quite a few changes since that post was made. I now have PCV, EGR, vacuum advance, and torque converter lockup all connected, and I'm still using the '72 carb. I will need to move to the '76 carb eventually. The vacuum port for EGR actuation on the '76 is located so that it does not activiate until a bit after standard ported vacuum. Running EGR off of standard ported vacuum causes a bad bog when light throttle is applied at low speeds, such as slow takeoffs, and parking lot manuvers.

    Getting my timing all set up is still an issue, but my initial, and part throttle settings are much better than before.

    Using the Doug Roe book as a guide, I disassembled my '76 carb, and found a possible source for a vacuum leak... Somehow, a 1" portion of the gasket between the air horn and the carb body was missing! I was easily able to pass a feeler gauge through this before tearing it down. As I continued to take it apart, I found that there was a nasty, white, pasty goo around the jets on the passenger side, and a white powderish looking substance on the passenger side metering rods. Thinking about how the old '76 electra was sitting for the past 10 years, not being run, I can see how foreign material would collect in this manner. It was parked with the front passenger side facing downhill......

    Anyways, it looked as if the passenger side of the carb was pretty well plugged up, which I would think would have something to do with why it ran so poorly. I bought a rebuild kit, and am going to clean it up and install the new parts.

    As far as the TV cable linkage, I took the throttle/TV arm off of the '85 carb, and put it on the '76 carb. A friend of mine that's handy with a TIG machine welded the '85 arm to the '76 carb shaft. Just like stock, and alot cheaper than one of those aftermarket kits!!!

    I found that the carb has "DB" secondary metering rods, "50K" primary metering rods, "75" jets, and the hanger for the secondary metering rods is a "K". Does anyone have input on whether I should deviate from these pieces for my buildup?

    My buildup looks like this -

    '76 Block and Intake(EGR equipped)
    '72 Heads, non stg1, 3 angle valve job, otherwise stock
    8.98:1 calculated compression
    Straightline Performance Cam, 220/235 @ .050", .473/.476 duration, 112 lsa, 108lc (4 degrees advance ground into the cam)
    Stock exh manifolds, single exhaust

    I wouldn't think that my fuel requirements at part throttle would be that much different than stock, but, I really am not qualified to make that call! If anyone feels different, please chime in!

    Thanks!!!!!!
     

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