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#1
08-04-2008, 12:55 PM
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Q-jet fuel question
Can you have a combination of air bleeds and secondary rods that will drain the bowl even with good fuel supply? I have a holley red feeding a carter high volume mechanical and even with this it will nose over and quit pulling at about 5100rpm I have a new filter in the carb and no other filters. The system only has the gas cap for a vent. I know I should have 1/2 inch line and so forth but this is so much more fuel system than I ever had before and people are running low 12s with stock systems. So what do you think? And if I just need to start over is the Mallory 250 as good as the 140 the price is about the same?
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#2
08-04-2008, 01:48 PM
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what is the combo and what is it running ET? MPH?
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1980 TA 455 th400 2.56 posi 12.27@111.48 http://www.dragtimes.com/Pontiac-Tra...lip-29967.html http://www.youtube.com/watch?v=6X5XJ9PR1Qw https://www.youtube.com/user/hal101/videos |
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#3
08-04-2008, 02:56 PM
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My experience, which is limited compared to others who post on here, would indicate No to your first question, In fact it could be falling on its face with a bowl full of fuel, been there done that...
I'm not sure about stacking mechanical and electric fuel pumps, never done it, but the filter in the carb inlet could be part of your problem, I have never raced with it installed, try running without it... How much fuel was in your tank ? I run the stock tank, but I never let it get below 1/2 tank, mine will fall on its face somewhere around 3/8th tank, so I use 1/2 tank as empty... If you are going to upgrade the electric pump, I would suggest going a little overkill, then it is less likely you will end up needing more pump later, I'm sure others will provide their opinions, Pronto... Stick with it, that Q-jet will do just fine...
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1969 Firebird, Tx3-455/468 machined by CVMS E-heads by Dave Wilcox/Comp Cams 300B-6 flat solid 850DP on E-85 by Eric Niefert/T2 1" plastic spacer T-400/PTC 4000/390's/30x9 Hoosier radial slicks,#3400 1.38 60' 6.32 @ 108 MPH at Northeast Dragway NC 5/23/15 (9th pass on new engine) https://m.youtube.com/watch?v=ePCu2v...ature=youtu.be 1.37 60' 6.26 @ 109 half track, 9.86 @ 136 1/4 mile, #3350 11/26/16 at Richmond Dragway (125th pass on new engine) |
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#4
08-04-2008, 04:56 PM
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combo
.030 455 edelbrock heads, rpm intake , xe 284 comp cam , 62 tempest , 3700 stall converter, 2.5 exhaust with round port manifolds, 3.27 rear gear with 26inch tires. Has had fuel issues with old motor 12.7 at 104mph with just the holley red pump would wait till the top of second before it layed over. So I took out the fram filter and added the mechanical pump. Still issues. The carb is a 83 chevy truck carb and had blunt secondary rods so I put in 70ish[year not size] pointed rods out of old pontiac Q-jet is a little rich but not bad. Full tank,.3/8 metal all but 1 1/2 foot which is rubber 3/8
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#5
08-05-2008, 06:10 AM
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do you have the large needle and seat in the carb
__________________
1980 TA 455 th400 2.56 posi 12.27@111.48 http://www.dragtimes.com/Pontiac-Tra...lip-29967.html http://www.youtube.com/watch?v=6X5XJ9PR1Qw https://www.youtube.com/user/hal101/videos |
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#6
08-06-2008, 08:38 AM
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I have a stock 3/8" fuel line size.The car is 3800# stocker with SD455.I use the blue Holley with Fram large filter at the stock tank.I bypassed the stock fuel pump.I did braze a fitting to large Buick inlet nut so I could have an idea what the pressure is at the carb.I want to update to a larger fuel line sometime.Cliff gave me the info I just haven't spent the $.
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#7
08-07-2008, 06:07 AM
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I tried feeding a Carter HP mechanical pump once on my car with a Holley Red pump. Got a nose-bleed on the first run, when my face bounced off the steering wheel at the top of first gear! This was back when my car ran mid to high 12's. Not sure why it didn't work, as others have had decent success pushing/pulling with combinations of electric and mechanical pumps. I quickly moved to a better electric pump and got rid of the mechanical. We ended up sumping the tank one Winter and going 8AN lines/fittings everyplace, with the pump and filter behind the tank.....haven't had a single fuel delivery issues since......Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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