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Technical SBC bent fuel pump rod WTF

Discussion in 'The Hokey Ass Message Board' started by 31Vicky with a hemi, May 5, 2022.

  1. no it wasn’t the bolt!

    Of course, there’s quite a few google hits on this problem and no good answers. Not one! Lots of feed back saying “ I’ve been wrench for 50 years and never heard of that”

    I don’t know what the hell happened to this damn thing but it was installed the same way I’ve installed 100 or so over the last lifetime.

    It’s brand new engine (I didn’t build it) engine was started and broke in on stand by builders with Electric FP. It’s brand new rod, (because nobody could find the old one) 1 year old pump. Engine on stand, installed the pump, as well as a few other things, flipped it over and swapped oil pans, off the stand bolted up transmission. Rolled over by hand for TC bolts. Put it in car and hooked it up all the other stuff. Tried starting it.
    Not getting fuel, diagnostic led to fuel pump coming off. Pull this out ,,,

    10599891-17BA-4FEA-996F-1CE2A04DD662.jpeg 53BB4BF8-8D28-4D1B-ABF6-09A949784DE8.jpeg

    Awe hell ,,, how exactly does that get bent and turn over by hand? No noises or groaning from starter. I don’t get it
     
    anthony myrick likes this.
  2. I could be wrong, but the “new” statement is what makes me think the rod isn’t made from the material it should be. I’m going to guess it is way too soft of material. Heck, I use a small block fuel pump rod as a drift and have never even came close to damaging it smacking it pretty hard. As far as what caused the actual bend, all I can come up with is that maybe the pump arm missed the rod somehow when installed and put it in a bind? Then, once it bent and cleared, it missed the contact point on the pump arm making it not pump fuel? Or maybe the rod is just so soft it couldn’t overcome the pump without bending?
     
    Bob Lowry, chevyfordman and clem like this.
  3. 47chevycoupe
    Joined: Dec 25, 2007
    Posts: 543

    47chevycoupe
    Member
    from Finland

    I have seen one other fuel pump rod bent that way. The rod fell down when the pump was bolted on and the arm in the fuel pump bent the rod.
     
    ottoman, Mr48chev, NoelC and 5 others like this.
  4. egads
    Joined: Aug 23, 2011
    Posts: 1,419

    egads
    Member

    ^^^^^^^^^^^^^^^^ This
     
    ottoman, Mr48chev and guthriesmith like this.

  5. 37gas
    Joined: May 25, 2013
    Posts: 143

    37gas
    Member

    I have done that before, I put too long of a bolt in a Hurst engine mount and I't bent the rod in the same place.
     
    -Brent-, kevinrevin, ottoman and 2 others like this.
  6. Never seen that before either. Those are hardened, at least they were. Can't believe that itis bent like that.
     
  7. It’s a First for me. Obviously something went wrong here but the install process seemed flawless,,,, lube and instal rod, made sure it was on the low side of cam eccentric, install long bolt just snug install plate, install pump, felt slight tension, evenly tightened bolts, removed long bolt, thread sealer and short bolt.
    Text book ...
     
    GlassThamesDoug likes this.
  8. I’m trying to picture the bending method and exactly when,,,, rolled that motor over by hand at least 2x after pump installed and felt no resistance, nothing wrong and nothing odd when using the starter motor.
     
  9. Yep, procedure sounds exactly like we have all likely done it many times. That is why I am questioning the hardness or just material of the rod.
     
  10. Put the rod in a vice and see how hard it is too bend, just curious.
     
  11. ramblin dan
    Joined: Apr 16, 2018
    Posts: 3,609

    ramblin dan

    Holy crap, that's a first for me. I would be concerned what that did to the cam. When I install one I usually blob a bunch of white grease in there which will hold the rod in place till you get the pump in place.
     
  12. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,802

    jimmy six
    ALLIANCE MEMBER

    Newer ones are hollow with hardened ends. We use them on our race engines…
     
    Montana1 and Fogger like this.
  13. Wow! I would have never guessed newer ones were hollow!
     
  14. Fogger
    Joined: Aug 18, 2007
    Posts: 1,804

    Fogger
    Member

    I have three small block powered cars and all have the fuel pump push rod that Jimmy described, hollow with hardened ends. Since '63 I have always held the push rod against the camshaft so the rod is at the base of the lobe. You can feel it while slowly turning the engine over. With the engine in that position there is less tension on the fuel pump and rod when it's installed.
     
  15. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,802

    jimmy six
    ALLIANCE MEMBER

    Lighter and faster for us but they are way less expensive to make.
     
    Last edited: May 5, 2022
    guthriesmith likes this.
  16. moparboy440
    Joined: Sep 30, 2011
    Posts: 1,087

    moparboy440
    Member
    from Finland

  17. Fordors
    Joined: Sep 22, 2016
    Posts: 5,373

    Fordors
    Member

    I’ve seen the hollow p/r at least 30 years ago, I think it was from Moroso BITD. Are you guys saying Chevy made them too?
     
  18. Budget36
    Joined: Nov 29, 2014
    Posts: 13,174

    Budget36
    Member

    I’ve got one from years back that snapped. Not a sign of a bend in it at all. The “break” looks like a snapped drill bit, always assumed they were a hardened rod.
     
  19. Driver50x
    Joined: May 5, 2014
    Posts: 421

    Driver50x
    Member

    About 30 years ago a friend of mine had a small block Chevy do that three times. We were both fairly experienced wrenches, and we never did figure out what was causing it. His would go about 100 miles before they bent. Best of luck.
     
    GlassThamesDoug likes this.
  20. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 12,603

    Johnny Gee
    Member
    from Downey, Ca

    Any other change if any at the forth rod? Like less stay another fuel pump.
     
  21. Driver50x
    Joined: May 5, 2014
    Posts: 421

    Driver50x
    Member

    He tried a different fuel pump and that did not fix it. He “fixed” the problem by selling the car! It was a fresh rebuild with a new aftermarket camshaft. I always figured maybe something was wrong with the cam.
     
    Johnny Gee likes this.
  22. SASROD
    Joined: Feb 7, 2007
    Posts: 149

    SASROD
    Member

    You said it was a "brand new" engine. Old block or new? I thought some newer blocks were not machined for a fuel pump. Could whoever built the engine incorrectly drilled for the rod?
     
  23. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 12,603

    Johnny Gee
    Member
    from Downey, Ca

    That would be something.
     
  24. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 12,603

    Johnny Gee
    Member
    from Downey, Ca

    Not if one uses...

    upload_2022-5-5_9-31-35.jpeg
     
    jimmy six, egads and Roothawg like this.
  25. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,904

    Happydaze
    ALLIANCE MEMBER

    If turning the engine by hand resulted in that you must have hidden strength! Hamb superhero, licenced to wear underwear externally!!
    Chris
     
    Jibs and 41rodderz like this.
  26. I know right?
    I’m just trying to get my head around the actual pivots forces and stop of how the damn thing Got bent in there. Long part was up towards cam,,, rod came right out
     
    1949*john likes this.
  27. 41rodderz
    Joined: Sep 27, 2010
    Posts: 6,540

    41rodderz
    Member
    from Oregon

    :D
     
  28. Seasoned block,
    Blueprinted machining all surfaces, everything new.
     
  29. Well I must’ve leveled up on this one,
    Because there’s a whole Lotta guys that have never seen this one. Just a few who have
     
    Lloyd's paint & glass likes this.
  30. One end contacts the cam the other end contacts the fuel pump. Between those spots the rod contacts/rides in/is guided by the block itself.

    The bend is happening between the fuel pump and the block. If the rod was binding in the block I would expect the bend to be between the cam and the block. The way I see it, something happened (jammed?) with the fuel pump, the cam pushed down on the rod and the rod slid off the fuel pump and bent.

    I have never seen this happen before but I believe you have an issue with the fuel pump. Turning the engine over by hand is not the same as firing an engine up and running it at 600rpm. The issue wasn't obvious (or even an issue yet) when turned over by hand ... the same can't be said for when it fired.

    I have a Masters degree in Intergalaxational Multidirectioning Plasmodic Disectionism (that was unfortunately not earned on this planet) so I have an inkling how things work ... it's your fuel pump ;)

    If the install of the pump was done correctly, then it's an issue with the pump itself.

    Edit: Are you absolutely positive the rod you used is for a SBC and it isn't too long? Just because the box says SBC doesn't mean the correct part is in the box.
     

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