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Rough running EZ EFI 1.0

Discussion in 'FAST Support Forum' started by Yadkin, Aug 23, 2016.

  1. Yadkin

    Yadkin Member

    Joined:
    Jul 22, 2013
    Location:
    Yadkin Valley, NC
    Thanks AA. Your math is off a bit but I get what you're saying, which is:
    • Black bushing
    • Use the springs for curve B
    • Initial advance 10 degrees with vacuum unplugged
    Therefore timing will be:
    • At idle 10 degrees initial + 16 vacuum = 26 total
    • At 3400 RPM WOT 10 initial + 18 centrifugal + 6 vacuum = 34 total
    • at 3400 RPM cruise 10 initial + 18 centrifugal + 16 vacuum = 44 total
     
  2. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Lol, that should have been 50. At cruising RPM, total should be about 40-44.

    You're confusing the 4200 factory all-in mechanical slope these distributors come set for using the heavy springs with what it is using the lighter springs. The first spring change, from factory, only drops the all-in mechanical slope to about 4000. The bushing only locks in the total number of degrees available for use. Using the springs for an all-in mechanical slope setting of 3400 can cause detonation due to the faster rise of degrees at RPM. 3400 would be a good highway cruise speed RPM.

    At 3400 RPM, your distributor will only supply a high percentage of the total mechanical advance available from the bushing used - so long as you haven't used the lighter springs for the all-in 3400 slope. You might get away using the springs for a 3400 RPM all-in slope, but only try that using one step lighter spring at a time. The load on the engine determines how low you can set slope - and your Thunderbird isn't a very light vehicle.

    Remember, you have two sets of silver springs supplied with the distributor - a heavy set and a light set. Don't let MSD confuse you. Those graphs are only an approximation for some understanding. If you had use of a distributor setup machine, you would see the entire mechanical slope - advance degrees at each RPM.

    • Black bushing
    • Use the springs for curve B (just use the next lighter spring with the heavy spring)
    • Initial advance 10 degrees with vacuum unplugged
    Therefore timing will be (using the heavy spring and one step lighter spring) :
    • At idle 10 degrees initial + 16 vacuum = 26 total (this can be varied as needed for steady vacuum - including fulltime or part time TBI vacuum port use)
    • At 4000 RPM WOT 10 initial + 18 centrifugal + 6 vacuum = 34 total
    • at 3400 RPM cruise 10 initial + 18 centrifugal + vacuum = total about 40-44
     
  3. Yadkin

    Yadkin Member

    Joined:
    Jul 22, 2013
    Location:
    Yadkin Valley, NC
    I set that tune yesterday by changing one spring then set the initial timing to 10, and the car ran very nicely, good power. However my fuel mileage has not improved. I also measured the total vacuum advance at idle by comparing the crankshaft degrees with the canister unconnected/ connected and found that it is advancing 12 degrees, not 16 as MSD states. So this is what I actually have:
    • At idle 10 degrees initial + 12 vacuum = 26 total
    • At 4000 RPM WOT 10 initial + 18 centrifugal + 6 vacuum = 34 total
    • at 3400 RPM cruise 10 initial + 18 centrifugal + vacuum = total about 36-40
    I'll try increasing the initial incrementally by road testing at WOT to determine knocking, but a better solution would be to install an adjustable vacuum advance.
     
  4. Yadkin

    Yadkin Member

    Joined:
    Jul 22, 2013
    Location:
    Yadkin Valley, NC
    Just ordered the Crane adjustable kit.

    By the way, I added a pair of switches to my ignition system to allow bypass of the box. This allows me to time the engine without the multi spark interference. I also found a nice period fender badge and installed it on the air cleaner.
    P1100268.JPG

    The left switch is the tach source to the FAST ECU, and the right switch is distributor only/ 6A box.
    P1100266.JPG
     
    A A likes this.
  5. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    That emblem is a nice touch.:)

    Before adding the new vacuum canister, there are two things you could try. First, try raising the initial two degrees. If that works out good (idle vacuum steady, no pinging, or pre-ignition/oil appearing on the plug inner ceramic), go another spring lighter to get a 3800 RPM all-in slope. If there are again no adverse effects after going to 3800 RPM all-in, keep either or both settings. 3500 was the Ford factory all-in mechanical slope, but the lower fuel octane of today could make getting closer to that number a problem.

    You need about 40-44 degrees of timing at 3400 with the vacuum connected - to see more mileage improvement.
     
  6. Yadkin

    Yadkin Member

    Joined:
    Jul 22, 2013
    Location:
    Yadkin Valley, NC
    The emblem was advertised on Ebay as "looks like NOS"; it does. They make 'em in red/ black or black/black. I think the touch of red gives it just the right amount of pop. I cut the three studs off the back and bent it over a wood shim by hand to the shape of the air cleaner. A blob of Goop Automotive keeps it in place.

    Since I already ordered the adjustable vacuum advance and it arrives on Tuesday I'll just go that route.
     
  7. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Hey! How's that new vacuum modulator working? I've kept my fingers crossed for you so long the arthritis is hitting them. :D
     
    Pfingstl likes this.

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