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Holley 94 fuel pressure query...

Discussion in 'The Hokey Ass Message Board' started by drillmastertommy, May 9, 2010.

  1. I have a 59ab v8 flathead running a pair of holley 94's on an offy intake. I also have been suffering vapour lock issues lately so to cut a long story short I have fitted an electric pump as close to the tank as poss, junked the previous owners nasty attempts at inline filtering and fuel line routing which instanly leaked everywhere with the added pressure and then she ran sweet!...... for a trip round the block, then died at idle with fuel pouring out of the carb that previously didn't appear to be getting any.

    I put a gauge on the fuel line to check the electric pumps pressure and I appear to be getting 6psi which sounds too much to me. I have searched a number of threads a can't settle on a definitive answer.

    Can somebody tell me what pressure I should regulate my fuel to these carbs at please, it would be really nice to go out and drive for a change without it being just to check what my next problem is!:eek:
     
  2. OLLIN
    Joined: Aug 25, 2006
    Posts: 3,076

    OLLIN
    Member

    I am running a 2-4psi electric fuel pump on my 8ba with 2 94's and I dont use a regulator. It seems to work at that pressure. Maybe put a regulator on yours, if not, I got mine at the local VW parts house for $29.00 and thats chap enough to keep a spare one in the tool box..
     
    porknbeaner likes this.
  3. 29SX276
    Joined: Oct 19, 2003
    Posts: 469

    29SX276
    Member

    OLLIN is bang on;I run a pair of '94's,an A/C fuel pump that puts out 6 psi,but I have a Holley regulator that cuts the pressure back to about 2.5 lbs.Never a problem with flooding.Take care to set the float levels properly,use the steel needle in the needle and seat.Above all,use a good filtre.
     
  4. walls
    Joined: Oct 6, 2005
    Posts: 536

    walls
    Member

    i run 1.5 on my 94's with no problems but, i don't really know what i'm doing.:)
     

  5. dirthawker1313
    Joined: Apr 18, 2005
    Posts: 648

    dirthawker1313
    Member

    i run 1.5 to 2 psi on my 51 ford.
     
  6. VOODOO ROD & CUSTOM
    Joined: Dec 27, 2009
    Posts: 1,238

    VOODOO ROD & CUSTOM
    Member

    Ford "Spec" is 3.5 to 4.5 p.s.i. No more or you'lll have the described issues.

    Good Luck with the Flatty !!

    VOODOO
     
  7. VOODOO ROD & CUSTOM
    Joined: Dec 27, 2009
    Posts: 1,238

    VOODOO ROD & CUSTOM
    Member

    Here's some "tech" from www.btc-bci.com/~billben/fuel.htm
    They have great "tech" for your flatty !!

    FUEL PUMPS:
    Flathead Ford stock fuel pump pressure is 3-1/2 Psi. The fuel pump pressure can be adjusted by adding or subtracting fuel pump stand gaskets. The gaskets we get in engine gasket sets are quite thin (about 0.010” thick) .,.. and we only get one. What I use are 8BA thermostat housing gaskets to adjust the fuel pump stand height to decrease the pressure down to the 3 1/2 psi. I want. They are only slightly larger, but are considerably thicker. On my ‘34, I had to use two of them to get my new Carter fuel pump pressure down to 3 1/2 psi from the 4 1/2 psi it came with.
    Just because the fuel pressure is within specifications does not mean the fuel pump is good. It can have good pressure but not pump enough volume. It has to pump at least one pint of gas within 30 seconds with the engine running between 500 and 600 rpm.
    Fuel pump push rods are supposed to be replaced when wear exceeds 0.010”. If wear exceeds this amount, the pressure/volume may be insufficient to feed the engine when asked to run flat out or during a hot summer day. Watch the amount of chamfer on the cam end to determine when they’re worn out.
    Ford, Holley, and Stromberg carburetors were designed to run on 2 1/2 psi fuel pump pressure not the 3 1/2 to 4 1/2 psi the stock mechanical fuel pump is supposed to deliver. Why Henry made a fuel pump that puts out more pressure than the carb can withstand is beyond me. I use an adjustable type fuel pressure regulator located between the stock fuel pump and the Stromberg carbs and set it at 2 1/2 lbs. This prevents flooding from too much pressure on the needle seat assembly.
    When you’re performing your spring tune-up, be sure you tighten the screws that hold the fuel pump together since they relax with age. Also check the glass bowl bail to make sure it’s tight also. As these relax they will suck air instead of fuel and cause you to stall on a hot day. I recommend you check them in the spring and again before you take a long trip across country.
    FUEL PRESSURE REGULATING:
    Fuel pressure is very critical to these early carburetors. Early Ford Motor Co. shop bulletins and manuals state the Ford/Holley/Chandler Grove and Stromberg carburetors are all designed to operate at 2 1/2 psi. Yet the fuel pump delivery pressure spec’s call for 3 1/2 psi ! I don’t understand the thinking behind this. The Strombergs are very sensitive to fuel pressure because of their float/needle valve design. It just doesn’t exert enough pressure to overcome the fuel pressure. They have a tendency to flood when fuel pressure is in the neighborhood of 3-1/2 lbs. On these carbs I install a pressure regulator and set it at 2-1/2 psi. This regulator HAS to be physically located between the fuel pump and carb since the fuel pump is putting out 3-1/2 Psi. If you’re entering your classic car for judging, then carry a spare fuel line without the regulator and replace it when you get to the meet.
     
  8. Cheers for the info guys, got a low pressure Holley regulator being delivered tomorrow so fingers crossed I will be able to cruise with confidence later in the week.:D
     
  9. six pack to go
    Joined: Aug 2, 2008
    Posts: 1,938

    six pack to go
    Member
    from new jersey

    Hey guys, Im having similar trouble...where can I purchace a adjustable type fuel pressure regulator or the above mentioned low pressure Holley regulator? Thanks ~E
     
  10. Kirk Hanning
    Joined: Feb 27, 2005
    Posts: 1,603

    Kirk Hanning
    Member

    When I had a holley low pressure regulator on my 4 duece setup on a Cadillac using 94's I'd try to keep the pressure at about 3. Sometimes the finicky regulator would fluctuate and the carbs would be getting as much as 8 lbs of pressure without any issues, I guess that I just got lucky?
     
  11. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member

    I have two Holley 94's and I'm running an electric fuel pump for a Ford Ranger..I have no idea what the pressure is but it runs fine.
     
  12. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member


    Summit
     
  13. six pack to go
    Joined: Aug 2, 2008
    Posts: 1,938

    six pack to go
    Member
    from new jersey

    Found it thanks....
     
  14. shainerman
    Joined: Apr 18, 2009
    Posts: 820

    shainerman
    Member

    anyone have the part number for the Holley fpr you are running?
     
  15. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    And if you use the small round chrome regulator sold from lots of sources, results will be entirely random...
    Fuel pump spec (1947 bulletin) is 1 1/2 t0 3 1/2. I think some sources will get you a brand-new pump with modern spring set for twice that, so get the old one out of retirement.
     
  16. 46Chief
    Joined: Jan 2, 2008
    Posts: 163

    46Chief
    Member

  17. Realist
    Joined: May 3, 2009
    Posts: 17

    Realist
    Member

    The sweet spot for my dual 94s is 2 psig. Any more than that, my Charlie NY-rebuilt Holley's will flood.

    Charley NY 's a great guy to deal with. His work is second to none and he will always return your calls; so, if you need any carburetor work done, he's the man!
     
    3340 likes this.

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