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Technical Hilborn BL 420 pump

Discussion in 'The Hokey Ass Message Board' started by Grapes of Wrath, Mar 13, 2016.

  1. Grapes of Wrath
    Joined: Aug 6, 2014
    Posts: 19

    Grapes of Wrath
    Member

    Hello,

    Is anyone familiar with a Hilborn BL420 pump drive? I have a 420 and the drive on the pump is slotted but all the pumps I see are hex and so is my cam drive. It seems as if I'm missing a hollow shaft with a pin thru it that turns to hex?
    Any help is greatly appreciated.

    Thanks
    Kurt
     

    Attached Files:

  2. Mad Mouse
    Joined: Apr 1, 2007
    Posts: 93

    Mad Mouse
    ALLIANCE MEMBER

    I don't think you will find a modern pump with that drive. All you need is a spud to bolt on to the timing gear with a hex drive. Really no problem. Get it fron Hilborn.
     
  3. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,053

    dreracecar
    Member
    from so-cal

    More info is needed
    Is the pump a direct bolt on to the cover? or will a pump extention be used?
    What is the condition of the pump? is it fresh or worn out? Hate to get something hooked up only to find out its junk and cant be fixed or is inadiquit for the job.
    Back in the day those were bolted to the blower covers (hence the 3 bolt cover to the side of the drive) and the matching spade drive was bolted to the rotor gear,so you might start looking into old blowers for the drives. When the need for more fuel and extentions to clear the blower drives , the hex was needed to hold and support the shaft at both ends
     
  4. RichFox
    Joined: Dec 3, 2006
    Posts: 9,950

    RichFox
    ALLIANCE MEMBER

    I used an old BL pump on my '32 Plymouth banger. All I did was take a piece of hex stock and mill a blade on the end. I made it the right length so that bolting the pump to the drive held it in place. Any BL pump is really old and they were subject to wear from the start. I would send it out to have it flowed before I got to involved with it.
     

  5. Grapes of Wrath
    Joined: Aug 6, 2014
    Posts: 19

    Grapes of Wrath
    Member

    The pump bolts right to the hilborn cover, no extension will be used.
     
  6. Grapes of Wrath
    Joined: Aug 6, 2014
    Posts: 19

    Grapes of Wrath
    Member

    I was worried about it not staying centered in the pump groove.
    Did your adapter end up being 1"-2" long then?
     
  7. Grapes of Wrath
    Joined: Aug 6, 2014
    Posts: 19

    Grapes of Wrath
    Member

    I have the pump already in the pictures above
     
  8. RichFox
    Joined: Dec 3, 2006
    Posts: 9,950

    RichFox
    ALLIANCE MEMBER

    !cid_494F30C8-E8F5-4843-A0BB-7B4461A67F36.jpg
    As I remember, mine was around 3/4 or 1 inch long. Are you wanting to run this off the cam? On a belt drive. I think that if you run it off the cam snout it will be turning backwards. Maybe not. As you can see I ran mine off the oil pump. But it was the same as the belt drive Hilborn mount that was designed from a '48 Ford generator mount.
     
    Last edited: Mar 14, 2016
  9. Grapes of Wrath
    Joined: Aug 6, 2014
    Posts: 19

    Grapes of Wrath
    Member

    Ok. Very nice!
    I'm going to drive it off the cam.
     
  10. RichFox
    Joined: Dec 3, 2006
    Posts: 9,950

    RichFox
    ALLIANCE MEMBER

    By driving it off the cam you reverse the rotation of the pump. The later PG pumps could be set up to run which ever way you wanted. But the BL pump I am not so sure. It has been some time since I ran the BL. I think you should look for a PG 150 or some such. At least send it in for Hilborn to look at and advise you before getting to involved.
     
  11. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,053

    dreracecar
    Member
    from so-cal

    when they were mounted on the blower they rotated CCW.
    If I were to use this pump (based on it being able to reverse it) I would make a spacer with a bearing for support of the drive spud to eliminate any wobble. The drive spud would be of matching dia of the pump drive for a full contact spade and the male hex on the oppisite end for cam engagement and would use external snap rings to hold the spud to the bearing. Heat treating would also be needed for wear resistance.

    If the pumps were good ---you could still buy them new
     
  12. RichFox
    Joined: Dec 3, 2006
    Posts: 9,950

    RichFox
    ALLIANCE MEMBER

    On the Plymouth with a Barns pump, the adapter spud is no longer than the Hilborn hex on a PG pump. There is no room or reason for any support or snap rings. I ran mine at El Mirage and Bonneville for years with out any reason to think I needed extra support.
     
  13. RichFox
    Joined: Dec 3, 2006
    Posts: 9,950

    RichFox
    ALLIANCE MEMBER

    I think if I wanted to make this more complicated than necessary, I would make a sleeve that was a slip fit over the slotted shaft in the pump. Then I would silver solder it over the blade end of the adapter. So the blade would have to stay centered in the shaft. But I also think that if you actually do this instead of thinking about it, you will see that you don't need anything but the adapter.
     
  14. Grapes of Wrath
    Joined: Aug 6, 2014
    Posts: 19

    Grapes of Wrath
    Member

  15. Harv
    Joined: Jan 16, 2008
    Posts: 74

    Harv
    Member
    from Sydney

    Apologies for dragging up an old post. I had shared some BL420 overhaul info here a year or so back, but can no longer find that post. Info on the BL420's is scarce. I've got full tear-down and rebuild photos and measurements if anyone wants them. The reason for posting today is that I recently got my rebuilt pump flow tested. Figured I'd share the results here as they will be useful to someone.

    Looking to run this on a meth-fed, vane-blown, dry sumped GM Holden grey motor (138ci of pure terror :))

    Cheers,
    Harv
     

    Attached Files:

    Countn'Carbs likes this.
  16. Here you go.
    20200919_053447.jpg
     
    Countn'Carbs likes this.
  17. I was fortunate several years ago as I was at a flea market. selling a Hilborn BL 420 fuel pump. An old timer approached me, telling me that he had the Hilborn injected Pontiac engine that was on the cover of an older Hot Rod magazine, and he needed my fuel pump to complete his set up. He offered to trade my pump for a good PG 150 Hilborn fuel pump. I went to his house after the flea market, we traded, and we both went away happy.
     
    Countn'Carbs and Fordors like this.

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