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#1
07-03-2005, 07:56 PM
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finally got my q-jet straightrn out or at least I thought.The power valve is not being pulled down with 10 hg of vac.I swithed the dist vac to manifold vac and got 14 hg, but still the pwr valve will not depress for a lean idle.Could I have the apt down to far (2.5 turns?) is it poss that the vac has a leak with the apt down to far? The spring is a stock unit. Do the 78 motors have more vac than what I got? I don't know open for suggestions.
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87 GP le 455 200r4 3.42 rear |
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#2
07-03-2005, 09:20 PM
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whats ur cam specs probably need a lighter spring under the piston
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Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74  2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
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#3
07-03-2005, 09:26 PM
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Comp Cam xe274H 230 IN 236 EX @.050
488 in lift 491 ex 110 lob sep
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87 GP le 455 200r4 3.42 rear |
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#4
07-03-2005, 11:21 PM
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Pretty healthy cam for a 400.. i would try a lighter spring...have u done anything to add more idle fuel or idle air?
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Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74 2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
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#5
07-04-2005, 07:47 AM
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sry bud it's a 455
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87 GP le 455 200r4 3.42 rear |
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#6
07-04-2005, 11:36 AM
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Sorry I just seen your post about 78 and I knew there wasnt a 455 then .lol...I would still maybe change that spring out tho...
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Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74 2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
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#7
07-04-2005, 01:17 PM
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Power piston spring plays little roll, if any, if the idle circuit is corrected for the application. This reciept is a good start for a healthy 1976-80 Q-jet.
Carb # 17057274 jet 73 prim.rod 45L idle restr .055" idle tube .038" upper idle air .067 lower idle air .070" idle air bypass .080" idle discharge .096" main air horn .070" main air body .070" main air nozzle .052" sec rod BE .0410 sec pull out sec air tube .032 sec air valve/APT 1.38" / 4 turns from seated Don´t go wild on timing, 10-12 initial, 30-32 max mech. at 4500rpm. Reduce the amount of vacuum advance if you´re gonna use a fast timing curve, (all in at 3000rpm). |
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#8
07-04-2005, 05:09 PM
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Thanks for the info. Now I just have to fig where all the holes are.Let me go look in my Q-jet book.
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87 GP le 455 200r4 3.42 rear |
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