Clay Smith fuel pump.

Fuel and Air Systems

  1. rmchrgr

    rmchrgr Well-Known Member

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    I have a Clay Smith mechanical fuel pump on my small block Duster. Thing was a pain and caused me all kinds of grief. The pump body is huge, have to grind away a boss on the bottom of the block and it still barely fit. Then there's also the water pump inlet...

    To make the lines work you have to get an Edelbrock bottom plate, pn #1797. You plug the side inlet/outlet holes and run the lines out from the bottom since obviously there is no room to do it from the sides.

    Unfortunately, that part is no longer available!
    IMG_2785.JPG

    IMG_2817.JPG

    You can get pre-made carb. lines and a bracket that hangs the regulator off the pass. side carb. stud. I had th whole setup from AED (see below) but when I went to install it, the regulator was hitting the intake runner. I ended up making my own version. Ultimately I didn't need a bracket, the lines hold the regulator sufficiently.

    Here's the AED setup, which is also no longer available. Didn't work for me anyway.
    AED6093.jpg
    My version.
    IMG_2773.JPG

    IMG_2819.JPG
    Hope that helps.
     
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    • 4mulas

      4mulas Well-Known Member

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      This kinda shows how and where I did mine.
      702604F2-76CF-410A-9717-05847A42D8F2.jpeg
       
    • 67coronetman

      67coronetman Well-Known Member

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      Awesome job.. what is that black fuel line you are using that was a well thought out job.
       
    • 67coronetman

      67coronetman Well-Known Member

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      FB_IMG_1586764793899.jpg Anyone out here have a.
      Edelbrock bottom plate, pn #1797.
      I would really appreciate the help.
       
      Last edited: Apr 13, 2020
    • rmchrgr

      rmchrgr Well-Known Member

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      Thank you. The black woven hose is Russell Pro Classic, I’ve used it a lot. Nice and light, easy to work with and does not destroy your hands.
      https://www.summitracing.com/parts/rus-632073
       
    • 67coronetman

      67coronetman Well-Known Member

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      Now the trick is define one of those bottom plates I guess I'm going to have to put an ad out there and see if anybody has one lying around
       
    • 493 Mike

      493 Mike FBBO Gold Member FBBO Gold Member

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      That bottom plate, if flat on bottom side, looks real easy to fabricate.
      Mike
       
    • rmchrgr

      rmchrgr Well-Known Member

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      I have to say that these fuel pumps can be more of a pain than they are worth. Yes, they are very good fuel pumps but considering all the jive you have to go through to get them to work it would probably be more efficient to get a decent electric fuel pump.

      The original reason I chose to use one was because I did not want to deal with locating an electric fuel pump properly on an A body which can be tough to do. I even have a sumped gas tank but there is no easy or 100% safe way to locate an electric pump below that point where it's supposed to be. I had also been through a lot of electrical hassles on that car and had zero desire to add more with an electric fuel pump and it's associated wiring.

      Looking back I should have gone electric because I wound up creating way more work for myself and had to buy more expensive parts just to make the fuel pump work. After modifying a brand-new water pump inlet to clear the fuel pump body, the hose was too close to the fan belt. I ended up buying an electric water pump (more wiring!) and routed the inlet to the driver's side. That choice created the need to modify my nice, expensive aluminum radiator to move the lower hose to the driver's side. It really was a huge, expensive hassle for very little benefit.

      And even after all the fitment issues, I still had to deal with the fuel lines so I called Clay Smith to see if they had any ideas. They suggested the bottom plate. I really don't know how you would run the lines on any brand of block without the plate. It's hard to understand why the pump just doesn't come with a bottom plate to begin with.
       
    • khryslerkid

      khryslerkid FBBO Gold Member FBBO Gold Member

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    • 67coronetman

      67coronetman Well-Known Member

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    • 67coronetman

      67coronetman Well-Known Member

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      I do have the Carter fuel pump that's what I pulled off it wouldn't even hold 5 lb of pressure on a regular basis and I've got new filters new lines everything
       
    • snakeoil24

      snakeoil24 FBBO Gold Member FBBO Gold Member

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      The crap in new fuel destroys the diaphragm
       
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      • 67coronetman

        67coronetman Well-Known Member

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        Yes sir it does... Plus that crappy fuel also makes older cars on a vapor lock
         
      • RJRENTON

        RJRENTON FBBO Gold Member FBBO Gold Member

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        A curiosity question....
        Are your system VOLUME requirements so great that the Clay Smith pump is needed? Or a high pressure/volume pump? If your system is "running out of fuel" at the end of a 1/4 mile contest, are you sure the pump's volumetric capabilities are insufficient? It could be the carb's inlet needle valves are too small. Just about every fuel system I've seen has a pump that produces excessive amount of pressure that requires reduction b4 or at the carb's inlet. A gauge is always present. And its almost always its located under the hood, just where you cannot read it under load. True, a gauge is required to set the maximum pressure, but once that value has been set, the gauge should be removed, its connection point plugged, to prevent a MAJOR fuel leak if/when the gauges internal bourdon tube ruptures. This pressure sensing element is subject to the severe pressure pulses generated by the positive displacement fuel pump. IF a rupture occurs, say at the end of a contest, with a hot engine and exhaust manifold/headders, a catastrophe would occur. The morale of the story (?)....why does everyone (or almost everyone) think more pressure is better to fix a fuel starvation issue.....when the critical aspect is the volume delivered at the time of maximum demand. Just thinking out loud.....
        BOB RENTON
         
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        • Dan64

          Dan64 FBBO Gold Member FBBO Gold Member

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          I wanted to go with a mechanical fuel pump on the 493 for my 64' that i'm doing now . My engine builder has used a lot of Clay Smith pumps in roundy round cars with much success but the housing is massive and i'm not even sure you can still get them for a mopar anymore. What we came up with was a Carter super strip m4862 pump and we changed out the lower section to inlet/ outlet with a -8 fitting for the sake of volume ( still uses a stock carter diaphragm. Lines will be -8 to a return style regulator ( 7p.s.i.) with -8 return line back to fuel cell. Carter tech says on paper this pump in stock form is good for 900+hp but in reality figure 750ish. I don't know if the increase in inlet/ outlet size changes that info but i'm only @ 630 hp so not a factor for me.
           
        • Dan64

          Dan64 FBBO Gold Member FBBO Gold Member

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          73A715EE-D664-4C44-A298-DC04D4267CDD.jpeg
           
        • RJRENTON

          RJRENTON FBBO Gold Member FBBO Gold Member

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          Guel
          Fuel pumps are typically rated in EITHER gallons/minute at a specific pressure OR pounds/hour of fuel at a delivered pressure. Gasoline (fuel) is approximately 7.5 pounds/gallon. The question should be: how much fuel would "750 ish" HP (or 900+ HP) engine consumes for a specific time interval, that way a volumetric requirement could be calculated. Fitting restrictions and hose length losses can also be ented into a total flow loss factor (volumetric) to be used to determine IF the system's overall capacity satisfies the worst case conditions, not related strictly to horsepower. Just something to consider....
          BOB RENTON
           
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          • Dan64

            Dan64 FBBO Gold Member FBBO Gold Member

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            I got ya, it's a pressure/ volume/ time interval thing. Carter said ( doing the math @ 7 p.s.i. ) it would support my needs . On the other hand my engine builder didn't like the smaller inlet / outlet fitting sizes that that and the Holley come stock with so we came up with enlarging those fittings to utilize the available volume that a -8 line allows. Like sucking through a bigger straw giving you enough available flow for the time interval needed.
             
          • 67coronetman

            67coronetman Well-Known Member

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            Just curious are any of you guys running a return line with yours I had problems with vapor lock even with good fuel at times so I ended up putting a return line on and since I did that last year so far I haven't had an issue with vapor lock. My buddy Bobby who runs his car in the super stock nostalgia class had this very pump that I'm going to use on his car and he never ever had an issue with fuel not one but my current pump which is a car brand new from summit less than a year old cannot even maintain 7 PSI even six
             
          • coloradodave

            coloradodave FBBO Gold Member FBBO Gold Member

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            There are more than one Carter pumps. What is the number on the mounting flange? Perhaps you have the 'street' model pump...The Strip pump (8-9.5 psi) is #M4862.
             
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