Car falling on its face at 55-60 mph

Hienkel429Hienkel429 Posts: 183Member
edited July 2022 in HUDSON
Hello all, 

I am open to all ideas.   I just finished restoring the car last week and it is now legal!  (EIGHT years in the making)  Car is a 1951 Hornet sedan with a single range hydramatic and original rear end. The engine is a 55 308 crate engine from JC Whitney with factory Twin H.  Car is running with a new fuel system with a carter rotary vane pump (p4070) and a diaphram fuel pump delete.)  The carbs are correct and rebuilt with kits from Daytona.  I set the timing by vacuum.  Car starts the moment you touch the button and is perfect around town.  Getting on the highway it pulls very nicely on the on ramp up until I am about to merge around 55-60 mph.  Then it loses power, seems to be missing or flubbering (is that even a word) and can't get out of its own way.  Different throttle positions don't help.  It will maintain the speed but it is not a comfortable ride.  

I am at a loss and am open to suggestions.  Thanks all. 👍

Ray

Comments

  • 50C8DAN50C8DAN Posts: 2,687Senior Contributor
    edited July 2022
    There was a similar issue a few weeks back and it turned out the fuel filter was clogged (second filter that the owner did not know was there).  Not sure what to say about electric pump issues?  Was the dist. rebuilt and new coil?  Pertronix or points?

    One other issue that you may want to check.  Did you clean the fuel tank and reseal it or just dump out and refill with new fuel?  If you are using the old tank it could have lots of rust and junk.  Not trying to be a smartass, but throwing out a potential issue.
  • Hienkel429Hienkel429 Posts: 183Member
    Thanks Dan, 

    Running two filters. One before pump and a see through before the carbs.  Filter has fuel running through it.  Distributer was NOS with engine.  New points with correct gap, first new condenser I put in was bad out of box, new good condenser.  New cap and rotor as well.  New Pertronix 3 ohm Flamethrower coil with a new set of points. 

    Maybe something something mechanical advance?  That is something I have not messed with.

    Ray
  • 50C8DAN50C8DAN Posts: 2,687Senior Contributor
    Check the prepump filter that is what the other poster found was his problem.  Is that filter see-through or metal.
  • lostmindlostmind Posts: 1,529Expert Adviser
    It doesn't matter if it's see through, could be bad. I would bypass both filters, one at a time and road test.  Side of the road experience .
    Wellington , Ohio
  • Hienkel429Hienkel429 Posts: 183Member
    Just tested fuel pressure after replacing the rear. I have 7 psi at front carb, even with both filters.   Also cut open old rear filter, clean as a whistle. 
  • GeoffGeoff Posts: 4,605Senior Contributor
    Check the coil voltage.
    If you're stuck in a hole, stop digging.
  • Hienkel429Hienkel429 Posts: 183Member
    edited July 2022
    Both windings are good. 👍
  • ratlee2ratlee2 Posts: 348Expert Adviser
    Isn't 7  pounds too high.  I thought I remember someone saying fuel presseure was arounds 3 1/2 psi.
  • Hienkel429Hienkel429 Posts: 183Member
    Checked the rear-end.  Seems I have a 3:55. 🤷‍♂️
  • Hienkel429Hienkel429 Posts: 183Member
    The book says 3.5 to 4.5 psi.  
  • rusty_apacherusty_apache Posts: 230Member
    Sometimes capacitor manufacturers make several bad batches. 
    Find one from a completely different manufacturer if possible.  Just another wild guess, is the condenser matched to your flame thrower? 
  • D7feverD7fever Posts: 64Member
    Check your points, last time I put in points, I put the spring on the wrong side of the hold down.  Did the same as yours, checked, and discovered, put in the right way and it runs good. Could also be weak spring on the points.  Do you have a hose between your fuel pump and the tank? If so it could be collapsing at higher suction.
  • GeoffGeoff Posts: 4,605Senior Contributor
    The windings may fine, but if the input voltage is low, then you will run out of puff at high speeds.  You must have full battery voltage at the coil.   
    If you're stuck in a hole, stop digging.
  • Hienkel429Hienkel429 Posts: 183Member
    Geoff voltage is good.  

    Could it be the vacuum advance? I put a tac on it and it does its whole stumble /sounds like a popcorn maker around 2000-2100 rpms.  And the true speed this happens is right around 49-50 mph.  I evidently have the incorrect speedo gear.  

    Thanks all!
  • GeoffGeoff Posts: 4,605Senior Contributor
    Vacuum advance only works at high vacuum, i.e. when cruising or going downhill, so no, it will not affect the top speed if not working.  Sounds like fuel starvation to me.  
    If you're stuck in a hole, stop digging.
  • Hienkel429Hienkel429 Posts: 183Member
    Geoff...

    You are 1000000% correct.  Pulled the plugs and from looking at the ends this thing is LEAN!  Twin-h with wa1s and code 2113s tags.  
    From reading I've been told to check float level and metering rods. On meter rod tab bend down to richen and upwards to lean.  Also to raise the float which means a shorter distance between the top of the float and the inside of the top cover when inverted.   
    I know there is more that can be done but I am very limited in time and equipment after a valve spring cracked in two on a long trip. 

    I am learning.  Thanks all!

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