OEM Bendix fuel pump flow & pressure specs ? | FerrariChat

OEM Bendix fuel pump flow & pressure specs ?

Discussion in 'Vintage (thru 365 GTC4)' started by TTR, Jun 17, 2024.

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  1. TTR

    TTR F1 Veteran
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    I apologize for posting here rather than in "Technical" section, but figured there might be better chance to get answer(s), if any exists, since my interest relates to "Vintage" era pumps.

    So, has anyone here ever measured/tested OEM, 365 era Bendix fuel pumps for flow & pressure rates ?
    If yes, which (car) model(s) and/or if multiple, were there any detectible differences between pumps found in different model cars or were they all essentially same ?
     
  2. DWR46

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    Timo: What is the part number on the pump mounting flange? I can then give you the factory specs. I can also provide a quick lesion in 1960s Bendix pumps and the differences in what the made then. Email me.
     
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  3. TTR

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    Wow Dyke, that was quick !
    I’ll check the numbers on ones I have and email you tomorrow.
     
  4. gcalex

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    According to Eurospares listing (I don't have a copy of the C/4 parts book), both the Daytona and C/4 use "476087" pumps.

    As I am replacing my fuel lines and the like, I searched for info about the pumps, and the only things I found on-line were this table: https://www.pegasusautoracing.com/document.asp?DocID=TECH00023
    and variations on this table: https://www.aircraftspruce.ca/catalog/eppages/facetgoldflo.php

    For 476087 the consensus seems to be 12Vneg-gnd, 4.0-5,5psi, 36GPH

    The general claim seems to be that you can adjust the pressure by changing the internal springs, but that only makes sense to me if the flow rates in the second table are for "unloaded", rather than "max pressure".
     
  5. DWR46

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    Alex: The 476087 pump was the factory pump on these cars. This is referred to as the old "Silver Cap" pump. Flow rates are "unloaded".
     
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  6. TTR

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    #6 TTR, Jun 21, 2024
    Last edited: Jun 21, 2024
    Within last couple of days, I've been conducting some bench/laboratory tests on OEM and comparable new pumps and so far have found flow volumes of all at about 80% of manufacturer's claimed/suggested rates.
    Pressure rate testing still incomplete, but hoping to know more in a few days (ordered a second metering device to compare & confirm results).
     
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  7. TTR

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    In my test settings, the new replacement pumps seem to produce pressure at the low end of their claimed range, while both (used, 52 years/44K miles old) OE pumps did about 20% below their (originally) claimed low end of the range.

    YMMV.
     
  8. DWR46

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    Timo: Your test results would seem to indicate both the "new" and "old" pumps are satisfactory. If you can feed Weber's with 2.5-4.0 psi, that is plenty of pressure. If you can hold the throttle wide open in top gear until you get really scared, and the engine is still pulling strong, then you have plenty of volume and are good to go.
     
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  9. TTR

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    Dyke, that's pretty much what I concluded also ...

    ... and once I get everything else sorted*, will use the above method to confirm.

    *Just earlier today found more odd(?) issues with carbs, previously overhauled by someone else. :(

    And thanks again for all your advice.
     
  10. TTR

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    EDIT (following content was transferred from another, less relevant thread and I apologize if it has any errors or out-of-sequence replies):

    gcalex:
    Don't suppose you know of a source for that "fabric wrapped" style of hose, but with something like a SAE J30R14 rating?

    TTR:
    I don’t have a current source for the wrapped fuel hose and will be all ears if you find any.
    I found (& bought) some in a small bulk maybe 10 years ago and have been using it in my cars/restorations, but getting close to running out.

    gcalex:
    Yeah, I looked for a while, and sort of gave up. One can get high-pressure hoses of various sorts (though I never found any in smaller sizes) that have that same look, but they tend to have prominent labeling (so would have to be refinished in some way), and it is hard to tell what exact material they are made of (so one would be taking a risk using them for fuel).

    Certainly felt like there was no hope of getting that style of hose in a low-perm product, and an explicit ask from my spouse is to reduce the gas fumes as much as possible...

    TTR:
    Yes, there appear to be some wrapped-looking hoses available and at times seen in these cars, but I've found their material specifications less than confidence inspiring for fuel delivery use.


    Is your B/4 a U.S. market or ... and have you looked into all carbon canister & "green" evap hose stuff in the trunk, etc. to alleviate fumes/smell ?

    gcalex:
    My car is a Euro, so nothing to check… I am planning to add an aftermarket canister hidden in the trunk, to catch the tank vent.

    I actually doubt that the original hoses are made of anything that special, but anything without a “barrier” layer is going to gas-out more than I’d like (at least for the moment (my plan is the make everything as vapor tight as I can, and see if the improvement is noticeable)), and I do worry about the basic quality of hoses that are from a known supply chain…

    TTR:
    While there’s still plenty omitted from carburetors, I’ve managed to reduce gasoline odors noticeably in few Daytonas by just replacing all fuel related hoses, etc.

    As far as available hose construction and quality, I think one also needs to consider modern fuel chemistry being somewhat different than 50+ years ago and when choosing, safety, at least IMO, should overrule authenticity, no matter how picky we would like to be about the latter.

    gcalex:
    I certainly agree about the safety angle.

    To my thinking, modern fuels mean you probably should change vintage-correct hoses every year-or-two, and certainly check them every year.

    My bigger concern with "unknown supply chain" is the possibility that the hose could just be plain junk that is simply structurally defective.

    TTR:
    I agree about some of the available replacement hoses potentially having ineffective or unsafe construction for this type of use.
     

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