fuel pump acrobatics

Engine, Transmission & Driveline

  1. brent

    brent New Member

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    Three questions.
    q1: I was able to take off my fuel pump for a 66 monaco, 383. Getting the bolt nearest the block to line up again and thread-into the block is driving me nuts. I've spent an hour puttering to no avail. I even tried putting the old one back on, on the chance that some dimension of the new pump was altered. No luck with that experiment either.
    q2: Should I use a gasket glue on the fuel pump gasket? Putting glue on the fuel pump and adding the gasket makes sense but if I'm fiddling for an hour attempting to get the bolts installed and mounted, do I lose "grip" of the block-side glue?
    Q3: I see a rod inside the block's hole for the fuel pump that must be what the fuel pumps arm engages? When I've watched while a helper cranked the engine a few times I don't see it moving at all. Should it? if so I may have deeper problems.

    suggestions appreciated.
     
  2. D Cluley

    D Cluley Member

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    I'm going to guess that q1& q3 are connected.

    The rod inside the block has to be pushed up against the cam so that there is a gap between the rod end and the block where the arm on the pump goes.

    If the rod is dropped down against the block it won't move when cranking & the pump won't line up right because the arm is trapped on top of the rod.

    On the outside of the block, just below the hole where the pump goes there is a pipe plug. Use a 5/16" hex wrench to unscrew that and you can get the fuel pump rod out.

    Check the length of the rod while you have it out. Should be just about 3.25 inches.

    Put a glob of axle grease on the rod and reinstall it. The grease will hold it up so you can get the pump arm in place.

    If you can't get a finger in between the rod end and the block, then try cranking the engine to move the cam ( obviously not with your finger inside )
     
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  3. brent

    brent New Member

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    Very Helpful regarding Q’s 1&3. Thanks much!
     
  4. Toolmanmike

    Toolmanmike Super Moderator Staff Member

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    Q2 I use Indian Head Gasket Shellac on the fuel pump surface and glue the gasket on. Once it set's up for 10-15 min. it won't slip out of place. Nothing on the block side.
     
    Last edited: Oct 21, 2021
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  5. Trace 300 Hurst

    Trace 300 Hurst Professional Tinkerer FCBO Gold Member

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    Are you doing this with the alternator in place? If so, it's a miserable and difficult job.

    Remove that alt in two minutes, install the pump using what you've learned above, which should take another two minutes. It's easy if you know how. :thumbsup:
     
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  6. CBODY67

    CBODY67 Old Man with a Hat

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    (And nobody mentioned replacing the fuel pump push rod as a matter of "maintenance"?)
     
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  7. Toolmanmike

    Toolmanmike Super Moderator Staff Member

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    I was going to look up the length but got sidetracked. Hope someone chimes in.
     
  8. brent

    brent New Member

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    All helpful suggestions. I did remove the
    Alternator for better access and viewing. D. Cluely above, mentions the rod should be 3.25 inches. Will check that as well.
     
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  9. furious70

    furious70 Senior Member

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    If the rod isn't worn I'd leave it alone. Someone else wrote that too and deleted.
    That access plug can be impossible to get out fyi. Might need heat and strong man tools
     
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  10. brent

    brent New Member

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    Rod plug was easy to unscrew. The rod itself is 1/16th inch shy of 3.25 inches but appears to be in good shape, not battered. Is that measurement approximate and a huge issue? This engine ran okay before it suddenly didn't.
     
  11. 68PK21 440.6bbl

    68PK21 440.6bbl Old Man with a Hat

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    It's kind of funny that everyone talks about the pushrod length and nobody mentions the eccentric cam that is cast on the camshaft. Is there a dimension for this?

    I would think that this would be a major wear spot to look at on a old high mileage engine just as with a worn or flat cam lobe.

    :confused:
     
  12. thethee

    thethee Active Member

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    How would you check that without removing the cam?
     
  13. 68PK21 440.6bbl

    68PK21 440.6bbl Old Man with a Hat

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    I'don'kno.... Dial indicator with a long extension? I looked at FSM and didn't see any spec for anything on it.
    Aftermarket cams maybe questionable as to the eccentric dimension and hardness in that area.
     
  14. furious70

    furious70 Senior Member

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    It's always been a mystery to me why the fuel pushrods get consumed, the fuel pump spring is a wee bit lighter than a valve spring that might flatten a cam lobe...
     
  15. thethee

    thethee Active Member

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    Pure speculation but I'd imagine the fuel push rod is designed as a consumable item and therefore has a much lower hardness than the cam lobe such that the rod wears and not the cam. Would explain the lack of specifications in the FSM?
     
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  16. thethee

    thethee Active Member

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    Sorry @brent as I find this interesting but isn't helping you one bit :rolleyes:
     
  17. luigi164

    luigi164 Active Member

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    Found this on the www one time and kept it under my favourits for in case that....

    Photo albums
     
  18. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    I've always wondered this myself. Seems like when a lifter fails, the cam goes with it... Or is it the other way around?

    I haven't seen anyone ever saying "the fuel pump lobe was bad" on a used cam or any of the guys replacing the pump rod saying that the fix didn't work.

    Of course... Is it wearing at the cam only or is it wearing where it rubs the pump rod? Never heard that addressed either... and the action against the pump rod is a bit different and probably only oiled by the oil floating around in the engine.

    Possibly a lack of cam failures could be because the spring pressure on the fuel pump is lower than a valve spring too.

    Just something to think about....
     
  19. CBODY67

    CBODY67 Old Man with a Hat

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    As long as the pump pumps, it probably pumps more than the average driver really needs, even with a worn pushrod. Nobody probably ever worries about the pump pushrod length as the pushrod never is pulled out for inspection to SEE if it might be worn . . . unless it gets shorter than it needs to be or the stroke length diminishes such that higher rpm power is reduced? That pushrod lives in an oily mist all of its life, just as the timing chain does.
     
  20. '66 Fury I

    '66 Fury I Member

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    The "old guys" told me about adding "a bit of braze" to the wear area of fuel pumps when they lost output. Sounds they were making up for worn parts. I'm not suggesting this as a good solution, just for interest.
    On the cam wear issue; The "cam" that works the fuel pump is better described as an "eccentric". As was posted earlier, the spring load is much lighter than a valve spring and this coupled with the smoother action of the eccentric, the wear is greatly reduced. What do others think? Lindsay
     
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