I understand Q-jets

[Michael Skolones]

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     I think the point was that the Quadrajet couldn't take a high-pressure 
     electric fuel pump due to needle valve restrictions, whereas the 
     Holley units can take a stronger valve  and therefore a higher 
     pressure from an electric pump.  Apparently the mechanical pumps don't 
     put out enough fuel to keep either carb's bowl(s) filled, though I 
     have my doubts about this.  A pump is a pump, it's only a matter of 
     size.  
     
     Of course, there's nothing saying you couldn't have a lower pressure, 
     higher flow pump with fatter fuel lines on a Quadrajet.  That would 
     get around the valve problem.  
     
     The whole question is silly anyways; I'm sure that if you tried hard 
     enough you could get equal performance out of Q-Jets or Holley carbs 
     if they are rated the same CFM and sufficient fuel were supplied.  And 
     likewise I doubt that "all" hot rodders "couldn't" understand Q-Jets.  
     For some people, performance mods are influenced by style, 
     advertising, your buddy's opinion, etc, and "Holley" or "Edelbrock" 
     logos look a lot neater on your car and clothes than 'Rochester 
     Quadrajet".


______________________________ Reply Separator _________________________________
Subject: Re: I understand Q-jets
Author:  diy_efi at coulomb.eng.ohio-state.edu at Internet
Date:    9/18/97 12:48 PM


Paul:
     
If the mechanical fuel pump can't keep one bowl filled, how can it 
keep 2 bowls filled (assuming same rate of consumption & still only 
one fuel pump)?
     
Thanks - Daniel
     
> 
> 
> >>    There is a school of thought that the racers used to replace the
> >> Rochester QuadraJets with Holleys because they couldn't understand the 
> >> QuadraJets! 
> 
>         To be more correct the reason the Holley carb is used over a Q-jet 
> is because the Q-jet has a single fuel bowl in the center to feed both the 
> primaries and secondaries.  Mechanical fuel pumps cannot keep this bowl
> filled, and electric fuel pumps that can keep an average carb filled run at 
> a pressure that will blow past the Q-jet needle and seat, wich are only good 
> to 7 lbs. 
>         The Holley has two fuel bowls, one on each end, which can be
> extended to hold even more fuel.  Their needle and seats also hold 9 lbs. 
> and can be replaced with ones that hold up to 12 lbs.
>         I am not trying to start an argument, but there are people who 
> subscribe to this list that run Holleys, and it is not because we can't 
> figure out a  Q-jet.
> 
> Paul Tholey
> pft101 at psu.edu
> 
     
     
-- 
Daniel Grambihler
danielg at eskimo.com
'87 328 GTS  '95 D90 #3064 '96 900SS/CR
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Subject: Re: I understand Q-jets
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