New Guy: New to me 77 Ranchero

Discussion in 'New Member Welcome Center' started by Doc76251, Sep 17, 2018.

  1. Doc76251

    Doc76251 In Third Gear

    Messages:
    115
    Location:
    Virginia Beach, VA
    HA don't go far you know shit that works, and offer interesting points to ponder which sends me down rabbit holes I wouldn't have known to go to which learns me stuff. I am a firm believer that if a day goes by that I didn't learn SOMETHING new it was a wasted day.

    Cheers,

    Doc
     
  2. aquartlow

    aquartlow In Maximum Overdrive

    Messages:
    1,216
    Location:
    Summerfield Florida
    You adjust the primary transfer slot size by turning the curb idle screw CW or CCW, verify the transfer slot opening size(good baseline is .020-.025"-looks like a square, but it may be necessary to open them a bit more for radical cammed engines, sometimes up to .040"). Here is the curb idle screw for reference:
    [​IMG]

    This image shows where the vacuum secondary throttle blade adjustment screw is located, sometimes only accessed by removing carburetor from intake manifold. On a vacuum secondary carburetor, it is best to have VERY little to no secondary transfer slot showing when engine is at it's idle rpm setting, one of the reasons for this is upon deceleration the engine is usually in a low load and high vacuum situation and ANY part of the transfer slot exposed (whether on primary or secondary side) will essentially be a fuel mixture bleed(much too rich on deceleration) and adversely effect drivability.

    [​IMG]

    I hope none of my replies came out as being "preachy", not intended, just wanting to help you get this carb "on track" so you can actually enjoy driving your Ranchero.
     
  3. Doc76251

    Doc76251 In Third Gear

    Messages:
    115
    Location:
    Virginia Beach, VA
    AQL, you are not being "Preachy" I am having issues and you are providing sound, reasoned and dare I say experienced information at my request. Way back when on Page 2 I misread your post to indicate that the SECONDARY throttle plate should be set to show a "square". At that time with the carb upside down I could not figure out how to adjust the primary plates. It never dawned on me that the curb idle screw would do that, I was looking for an adjustment underneath, like the secondary.

    Based on all of the above here is what I am going to do next chance I get

    1. Leave the mixture screws alone, they seem to be adjusted to everyone's opinion of a good starting spot.
    2. Double check the float levels fore n' aft
    3. Unbolt the carb and cover the SECONDARY transfer slot
    4. Look to see if the primary is as closed as it should be with the Idle screw backed essentially all the way out.
    5. Bolt the carb back on
    6. Reset the choke delay to"zero"
    7. Fire that biotch up and see what happens

    Sound about right? Cover all the adjustment bases?

    Cheers,

    Doc
     
  4. aquartlow

    aquartlow In Maximum Overdrive

    Messages:
    1,216
    Location:
    Summerfield Florida
    Doc, it now sounds like you are on to something ;).
    Before you remove the carburetor, see if you can possibly install a screw/bolt in place of the secondary throttle blade adjustment screw that will protrude from the baseplate and allow any adjustments while the carburetor is bolted down, makes life a bit easier. If it can't be done, just adjust secondary throttle blade adjustment screw CCW and allow blades to just "bottom" out on the walls of the venturi, then adjust the screw until it JUST makes the blades move then add an additional 1/2 to 3/4 of a turn to open the secondaries. Verify that this adjustment doesn't uncover the secondary transfer slot(or VERY little of it), doing this and along with having .020-.025" primary transfer slot showing should be a good baseline setting to start with. If idle rpm is too high you can turn secondary adjustment screw CCW to close the throttle blades a bit thus reducing idle rpm. When adjusting idle mixture screws, wait until engine gets to full operating temp before any adjustments are made, using a vacuum gauge set mixture screws to give highest vacuum reading then add an additional 1/8 turn CCW to richen the mixture just a bit(make sure both screws are adjusted an equal amount from fully seated). I usually find this additional richness helpful with drivability. Hope this helps.
     
  5. Doc76251

    Doc76251 In Third Gear

    Messages:
    115
    Location:
    Virginia Beach, VA
    AQL, you should have professor behind your name!!!!

    The sun was up and it was a balmy 47*F when I got into it. Carb came off with no issues, did find that the throttle linkage was very loose tho. I inverted the carb over top of some unsuspecting weeds that showed up in my flower bed :cool:. Backed the secondary out till it quit moving and added 3/4 of a turn to when it started moving.played with the primary side and futzed with the fast idle screw until I got my little square and a little bit of adjustment on the idle screw. Pulled off the accelerator pump and inspected, she's all in one piece, screws were barley holding it on tho, not even finger tight. Adjusted the accelorator pump screw to snug it up and leave a .015" of travel. Flipped the carb over pulled out the 37 shooter and put a 31 with horns back in. Bolted the whole shebang back on the motor. Moment of truth time....

    Crank, crank, burble, crank crank, burble, crank, crank ..... VVVRRRROOOOMMM!!!!! Lump, Lump, Lump .......... and it just sat there idling at 500RPM!!!!!!

    I let it idle a bit and watched the choke cam come most of the way off and sh just sat there lumping along. I hit it and it was a bit flat but no pop no backfire. I added a bit more timing and she smoothed out some and the RPM's came up to about 600 ish. Drive time, shifted into drive and I wasn't sure it went in. Cruised around a bit and found my favorite parking lot. Matted the throttle and the ass end broke loose and started getting sideways, nice 30' snake stripe!!! Now that the motor was warm I adjusted the floats , the front was fine, the rear was a little heavy, fixed that. Adjusted to mixture screws to max vacuum in drive 2.5 turns each 10 mmHg. RPM's now happy at about 700.

    Thank you ll for putting up with my dumbassery, and thank you even more for the guidance to getting this thing right!

    Cheers,

    Doc
     
    Kiwirancher likes this.
  6. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    8,138
    Location:
    Everett, WA
    Just so you know, the low idle speed spec is 700, +/- 50, and a 50-100 RPM drop when put into gear. Hopefully, you just about have it there. So, good times coming!
     
  7. aquartlow

    aquartlow In Maximum Overdrive

    Messages:
    1,216
    Location:
    Summerfield Florida
    Always glad to help if possible and hearing it runs a whole lot better for you. Now go drive the hell out of it (it sounds like you already did, well just 30' anyhow) ;). Just an FYI, you want the accelerator pump arm to touch the accelerator pump diaphragm when at idle rest and have .015" clearance between the pump cam and accelerator pump linkage adjustment bolt/nut when @ WOT. This should help:
     
  8. Doc76251

    Doc76251 In Third Gear

    Messages:
    115
    Location:
    Virginia Beach, VA
    Yes Sir! It's just a touch under the 750 marker and drops down to 650. The motor is not quite perfect yet tho. I took her on a little run, burnt some more rubber and enjoyed the shocked looks of some folks at the light when I pulled up. My hood is longer than their Fiat:p. Coming home the opportunity presented itself to let her rip, I hit about ooohh twice as fast as the limit when I heard the can of rocks start shaking, I had another mile of clear road and said "piss on it". supposedly I should get a sticker or something on the windshield. Looks like I will have to back the timing off a touch and then finally address the Distro springs and bushings. The car is stupid fast and responsive at "normal" speeds and will pick up 20 mph right damn now. I really need a 5 or 6 speed w/ OD to make her run. I feel like I'm 17 again.

    Cheers,

    Doc
     
    Kiwirancher and HVAC22 like this.

Share This Page