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  1. #1

    Default 4160 accel pump setup

    I have a 1996 holley 600 vac secondary 4160 carb. I have a higher lifter cam heads etc. So I moved the red factory position to 2. This seemed to make it more responsive in neutral and got rid of bogging after 30 feet and now skids sideways 2 feet when it hits second on the c4 but town driving a small hestation off idle.
    I adjusted to .015" at WOT now in posution 2 does not move the cam untill 25% throttle.. cant adjust tighter as will bottom out the pump and spring on bolt will be loose.
    Do I try different jets on the squirter or what to do?
    I have a 6.5 power valve need to put in a 4.5 for my vac of 9" in gear(auto)
    Any advice?
    Thanks!
    Last edited by 78futura; 04-27-2019 at 01:36 PM.

  2. #2

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    You asked for it, lol...

    When I put a Holley together, the last order of business is installing/setting the accelerator pump/s for best function. First, I set the accelerator pump arm spring length to 5/8" with the bolt/nut. Next, put the pump arm onto the pivot stud and rest it on whatever installed pump cam you're using. Then, install the accelerator pump diaphragm spring and set the diaphragm in place. Now, sit the housing onto the diaphragm. If necessary, remove the pump arm and BEND THE ARM where it rides against the pump cam, until the at rest setting like above is is close, with no spring compression needed, and little to no slack/slop in the mechanism. Finally, with the idle speed setting/s where they need to be, tighten the spring bolt/nut just until there's slack, and then loosen the spring bolt/nut just until all slack is gone. Setting them this way utilizes the full lift of the pump cam (what dictates how much fuel is sent in), and there's always more than Holley's (minimum (virtually meaningless)) 0.015" clearance specification at wide open throttle so that the diaphragm is not being bottomed out.

    I'm going to bust a few snowballed myths here about Holley carburetors... carburetors in general with "power" circuits, actually...

    In your situation, take the red pump cam off and throw it away, lol... it's barely more shot than the factory usual white one... besides, the red pump cam has more lift (fuel volume that gets sent in) in position #1... seriously, try a green one in position #1, it'll like it very much... the green pump cam provides a much sharper rising crispier bottom end response and about 24cc of the theoretical 30cc in ten strokes (see image below)... but in general, remove the carburetor, empty it out, flip it over, remove the accelerator pump housing, remove the e-clip or clip holding the accelerator pump arm on, and proceed set/adjust like above.







    You change to a larger accelerator pump shooter size if the vehicle combination wants more fuel sooner, and vice versa. Pump cam dictates how much fuel gets sent in overall, and the shooter size is only a timing factor.

    If she's really only generating 9"Hg at idle in gear, you should find out what size the primary idle feed restrictions are... makes all the difference in the world when those are sized appropriately, most especially with "sporty" camshafts...

    Even if you had a 10.5"Hg or higher rated power valve with 9" of idle manifold vacuum, it's got nothing to do with how the idle circuit (or the transition (off-idle)) functions. The power valve channel restrictions being open/connected with the main wells by an open power valve at idle/off-idle does absolutely nothing to running idle/off-idle function, because the idle feed restrictions are what dictate how much fuel is in and can travel through the idle wells and circuits and to the idling engine. Put a power valve rated into the carburetor that adds additional fuel for when the loading calls for it when the main circuits, the boosters are in action... like say when your foot's halfway to the floor, and then some more for an incline in the road... see what your vacuum level is then, and put in a PV to suit that mode of operation with the augmented fuel from the power valve channel restrictions...
    Last edited by Walking-Tall; 04-27-2019 at 09:18 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  3. #3

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    I thought of bending the arm.. but thought maybe a different cam is needed. Sounds like both. The red was the factory one just thought maybe #2 would help. Will report back in a couple weeks after I order the parts. Need an accel cam set. Vac springs, power valves, quick change vac spring conversion etc.
    Thanks for the writeup. Little info online of setting the accel pump linkage except the .015" which is kinda a no brainer to a degree..
    Last edited by 78futura; 04-27-2019 at 10:26 PM.

  4. #4

    Default

    Oh btw great work on your carb info webpage! Will be a handy one stop resource for all carb info.

  5. #5

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    Yes, probably both. You can order things separately and at decent prices at AllState Carburetor (like a green pump cam and a purple secondary spring)

    You're quite welcome. Yeah, the repeated mantra for accelerator pump adjustment of 0.015" clearance at WOT... is... as I said above, a minimum, and pretty much not informative or logical or educational or useful at all...

    Thanks very much for checking out my site!
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  6. #6

    Default

    Quote Originally Posted by Walking-Tall View Post
    Yes, probably both. You can order things separately and at decent prices at AllState Carburetor (like a green pump cam and a purple secondary spring)

    You're quite welcome. Yeah, the repeated mantra for accelerator pump adjustment of 0.015" clearance at WOT... is... as I said above, a minimum, and pretty much not informative or logical or educational or useful at all...

    Thanks very much for checking out my site!
    If I lived in the states would be easy. Expensive here for parts and takes weeks. Try 5.50 a US gallon for premium.. 40 dollars a day to drive to work. 7.75 dollars with my tdi...

  7. #7

    Default

    I don't live in the states either. Jim and the team at AllState Carburetor don't charge big prices, and ship inexpensive and quick, to my experience so far.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  8. #8

    Default

    Quote Originally Posted by Walking-Tall View Post
    I don't live in the states either. Jim and the team at AllState Carburetor don't charge big prices, and ship inexpensive and quick, to my experience so far.
    Ok.. will do next time. There used to be a website sonething like carb gaskets or carb kits or carb parts or something lolol. I redid lots of old motorcycle carbs with those parts years ago for old kx1000s etc. Was 1/4th the price anywhere else and at least could be bought as many old parts are no longer.
    Now I need a kit for a 1963 simplicity landlord... lol..

  9. #9
    FEP Senior Member 854vragtop's Avatar
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    Default

    Great write-up! I too have always ignored the .015" setting and just adjusted to get all the slack out of the pump arm linkage in order to make sure the fuel starts moving a soon as I move the throttle. The green Holley pump cam is also the same pump cam that Summit puts on their 600 CFM carb right out of the box. It was also one of the mods that Mustang Monthly did to the 4180C factory carb in an article they wrote about solving hesitation back in the late 80's. I do have a couple of things to add though with regards to getting rid of all the hesitation.

    1) Make sure the engine is warm before adjusting the linkage. You want to make sure the choke is off and that the choke linkage is off the high idle detent, otherwise you'll have slack in the linkage when the throttle close slightly as it comes of the detent cam.

    2) Don't be afraid to experiment with the next size SMALLER pump squirter. Many times the throttle hesitation is not related to the volume of pump shot fuel, it related to how soon it takes to get there. The best analogy would be turning on a hose that's restricted and unrestricted, where it sprays out or just burbles out.
    Last edited by 854vragtop; 05-05-2019 at 07:38 AM.
    '85 Mustang convertible GT, 5 speed, 4V
    Stock bottom end, Comp Cams XE264HR-14, GT-40P heads w/ Alex's springs, Weiand 8124 Street Warrior
    8.8 Turbo Coupe rear end w/ 3.55 gears, Lincoln 73mm front calipers, SVO M/C

    '68 Mercury Cougar, w/ '88 5.0L, 4V
    My photo website:
    http://www.twilightphoto.com/

  10. #10

    Default

    Sounds good. I got a set of cams, vac springs, quick change vac canister, oh and MM fulllength subframes so I dot destroy the car completely.

  11. #11

    Default

    Quote Originally Posted by 854vragtop View Post
    Great write-up! I too have always ignored the .015" setting and just adjusted to get all the slack out of the pump arm linkage in order to make sure the fuel starts moving a soon as I move the throttle. The green Holley pump cam is also the same pump cam that Summit puts on their 600 CFM carb right out of the box. It was also one of the mods that Mustang Monthly did to the 4180C factory carb in an article they wrote about solving hesitation back in the late 80's. I do have a couple of things to add though with regards to getting rid of all the hesitation.

    1) Make sure the engine is warm before adjusting the linkage. You want to make sure the choke is off and that the choke linkage is off the high idle detent, otherwise you'll have slack in the linkage when the throttle close slightly as it comes of the detent cam.

    2) Don't be afraid to experiment with the next size SMALLER pump squirter. Many times the throttle hesitation is not related to the volume of pump shot fuel, it related to how soon it takes to get there. The best analogy would be turning on a hose that's restricted and unrestricted, where it sprays out or just burbles out.
    Thanks!

    Key points

    + Make sure the engine is warmed up before (finely) adjusting anything.Quite a mistake is to fiddle with mixture screws too much and things before the engine and intake and carburetor are fully warmed up to whatever operating temperature will be, since it will always be richest after warmed up. Apparent "good" function "cold drive-ablity", no protest when cold (and especially if there's no choke in action) is a sure sign that the idle mixture is adjusted too rich.

    + Always give as little fuel as possible, in all departments. Anything else is just a waste of fuel... and we all know what that costs nowadays.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  12. #12

    Default

    Quote Originally Posted by Walking-Tall View Post
    Thanks!

    Key points

    + Make sure the engine is warmed up before (finely) adjusting anything.Quite a mistake is to fiddle with mixture screws too much and things before the engine and intake and carburetor are fully warmed up to whatever operating temperature will be, since it will always be richest after warmed up. Apparent "good" function "cold drive-ablity", no protest when cold (and especially if there's no choke in action) is a sure sign that the idle mixture is adjusted too rich.

    + Always give as little fuel as possible, in all departments. Anything else is just a waste of fuel... and we all know what that costs nowadays.
    I got 25mpg driving to a car show and back home. I only romped on it maybe twice 1/2 throttle at 20kph and ran at 2750-2900 driving a bit slow but who cares.
    Not bad for no od and 400hp.
    Who said holleys drink fuel!

  13. #13

    Default

    I put my green cam in on position 1. I had the pink in not red came that way factory. I put a quick change vac secondary kit in and had the black one factory I put in a purple. Also went from a 195 to a 180 T stat. Set up the secondary idle up 3/4 turn in. Set up the accel pump correctly for full stroke.
    Test driven and is snappy and if I rev it it jumps to 5k right now. The people at the knights of the blue oval loved the way it sounded. There was a factpry 63 427 8v galaxie black on black and a mint gt350h there as well..
    I won a prize for longest distance to go to the show.

  14. #14

    Default

    Sounds like the way a healthy small block Ford with a carburetor on it ought to run, efficiently, AND snarlin', kickin' a$$ and takin' names
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  15. #15

    Default

    Yes great info on this thread. It is very relevant to what I'm messing with right at the moment.

    Interestingly I purchased one of those summit 600 carbs with the green pump cam and have it installed on a 306 engine with edelbrock F4B intake that is currently rigged up on a test stand. Seems like a pretty decent carb actually. I think I got it adjusted decently but I notice that I get a puff of black smoke out the exhaust when I rev it quickly. Seems definitely related to the accelerator pump as no smoke when you slowly throttle up or even when it starts cold etc. Maybe this is this a normal thing considering that there is no load on the engine ?

    I tried playing with the pump adjustment but still puffs to some degree especially when you give it a good shot on the throttle etc. I am thinking I might need to go to a smaller pump squirter as mentioned above. The manual on the carb also says to decrease the main jet size for every 2000 ft altitude...which is where I'm normally at. The plugs say I'm set rich (sooty) but I also think I had the idle mixture a bit rich for a while.

    Any comments or suggestions would be welcomed. Carb tuning is something I'm finally just starting to get into haha !!

    Thanks in advance.

  16. #16

    Default

    Quote Originally Posted by at_the_junkyard View Post
    Yes great info on this thread. It is very relevant to what I'm messing with right at the moment.

    Interestingly I purchased one of those summit 600 carbs with the green pump cam and have it installed on a 306 engine with edelbrock F4B intake that is currently rigged up on a test stand. Seems like a pretty decent carb actually. I think I got it adjusted decently but I notice that I get a puff of black smoke out the exhaust when I rev it quickly. Seems definitely related to the accelerator pump as no smoke when you slowly throttle up or even when it starts cold etc. Maybe this is this a normal thing considering that there is no load on the engine ?

    I tried playing with the pump adjustment but still puffs to some degree especially when you give it a good shot on the throttle etc. I am thinking I might need to go to a smaller pump squirter as mentioned above. The manual on the carb also says to decrease the main jet size for every 2000 ft altitude...which is where I'm normally at. The plugs say I'm set rich (sooty) but I also think I had the idle mixture a bit rich for a while.

    Any comments or suggestions would be welcomed. Carb tuning is something I'm finally just starting to get into haha !!

    Thanks in advance.
    ... "... get a puff of black smoke out the exhaust when I rev it quickly"... when you rev it how much/far? Half throttle, to full throttle? If lower amounts of throttle opening, could be shooter's too big, or pump cam providing too much off the bat. If you're talking about winging the throttle quickly and to full throttle, try a less lifting pump cam, like the white one, which is decent off the bottom but less total lift. The pump cam (and arm adjustment) controls how much accelerator pump fuel gets shot in, and the shooter only controls how soon or how later in the throttle opening cycle that amount of fuel gets shot in. Not loaded on a stand makes a difference, but black smoke/plugs is black smoke/plugs. I'd see how it acts in the vehicle.

    How much camshaft are we talking about? How open (amount of transfer slots' exposure below) are the primary throttle blades for it to idle comfortably? If they're open more than approximate squares of the transfer slots showing beneath the primary throttle plates at (fully warmed up, no choke/fast-idle) idle, close them to expose approximate squares showing at idle, and open the secondaries some to compensate, if necessary. Doing that makes sure, even with a radical camshaft, that nice non-touchy idle mixture screw adjustments are possible and you can get it to idle the best it can, lean-best, efficient, non-stinky, non plug-sooting, etc...

    I wouldn't bother messing with jetting also until in the loaded environment where it's headed, in the vehicle... where plug colors can be looked at after some wide open throttle operation, truly only useful if a "plug chop" is done, where you go full throttle, taking the engine say at least to torque peak rpm in high gear, and shutting off the ignition, coast to the side, look at the plugs. Any other modes of operation and the plugs are getting black, it ain't the main jets that are the problem, but the idle/transition circuits or the cam/shooter.

    Since you mentioned sooty plugs, one thing I would check is whether the power valve's diaphragm or gasket are leaking... the evidence will be in the vacuum chamber behind the power valve or at the vacuum passage that goes through the base plate...
    Last edited by Walking-Tall; 06-13-2019 at 04:21 AM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  17. #17

    Default

    My apologies I just realized that I basically hijacked this thread. Perhaps I should have started a new one instead.

    Thanks Walking tall I will look into a couple of the things you mentioned.

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