Carb Tuning Issues

Discussion in 'Fox 5.0 Mustang Tech' started by lizardsman, May 9, 2013.


  1. srtthis

    srtthis the guy doing it does every local racers rear end

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    The squirter would be to lean if it spikes lean when you got to wot quickly

    What's the air fuel at wot? I'd also shoot for something around 14:1 cruising
  2. lizardsman

    lizardsman Member

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    I had a/f to 13 cruising and it was running 20 deg hotter and missing, so it was to lean. I don't have a data logger and cause it wont hook on the street at wot I have no clue. Hard to watch where I'm going and the gauge, but believe it's around 12. It seems she only wants to run rich. Would timing, or spark gape be playing a roll? I need to call msd because I see no increase in timing when I raise the rpm.


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  3. srtthis

    srtthis the guy doing it does every local racers rear end

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    Def could be timing related... How much total timing are you seeing?
  4. lizardsman

    lizardsman Member

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    Timing is at 15, but only seeing 2 deg at about half throttle. Should I go wide open to the rev limiter? I think the msd dis is adjustable. Plus I have my plugs gaped .43. Should I go back to .30? And Thanks for all the help, will definitely be following you now.
  5. srtthis

    srtthis the guy doing it does every local racers rear end

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    What are you using to advance the timing? Spring kit in the distributor? Also where is your wideband located?
  6. lizardsman

    lizardsman Member

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    I have no clue how to advance total timing. I only have experience with initial timing. And I have the wideban on the driver side right after the longtube header. I set the depth and everything the way the instructions said to. They just weren't clear where in the exhaust to place it. I need to find the instructions on how to adjust total timing on the dist.
  7. srtthis

    srtthis the guy doing it does every local racers rear end

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    What distributor are you running?
  8. lizardsman

    lizardsman Member

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    Msd 8542, Just pulled the cap and rotor to see what springs and bushing was in it. They locked out total timing. No weights, springs or bushing. Just ordered a new spring and bushing kits and weights. I have no clue what a crank trigger is but there is nothing on the balancer or anything like that compared to what I see online as a crank trigger. And I see no increase in timing when I raise the rpms. So will I see a better fuel burn under throttle and an increase in power when I remedy this unforeseen issue? and I probably should wait to do anymore adjustment to the carb until then, correct? I have it drivable for now, or I can put the .80 jets back in to insure It stays rich and don't go lean and burn up a piston. See how she runs tomorrow.
  9. srtthis

    srtthis the guy doing it does every local racers rear end

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    Crank triggers are another way of setting timing. We run one on the 275 car... I'd set your total timing around 32-34* total and change the cam spring weight set up based off how the car drives
  10. lizardsman

    lizardsman Member

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    Ok, I'm pretty sure I know what you mean. A crank trigger would be on the balancer correct? And they only offer one set of weights but different springs to change the curve of total timing. So like always, waiting on parts is always the fun part.
  11. RMRJR

    RMRJR Member

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    Go to the innovate motorsports web site and check out the tuning links. I had similar issues when I purchased my car and with their LMC1 and gauge along with their tuning links and the previously listed youtube Demon link the car runs great now. Just went to a car cruise at Ocean City MD 400 miles round trip and averaged 24.6MPG. Also FBO website for the larger limiter bushings in your distributor which will allow you to run more initial advance. That will help a carbureted motor tremendously. Timing first then fuel
  12. srtthis

    srtthis the guy doing it does every local racers rear end

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    dont agree with that one...
    lizardsman likes this.
  13. lizardsman

    lizardsman Member

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    The bushings affect total timing and have nothing to do with initial timing. The bushing controls how much total timing and the springs and weights control the total timing curve and rpm it reaches total timing. I can turn the distributor and advance the timing till it dies or blows up in my face. I've been reading a lot about carb tuning and appreciate the extra sites, as I love information. And srtthis has been walking me through this ordeal. If I ever got 24 mpg in my car I would give it away cause I wouldn't be driving it the way I should. I purposely beat on my car so I know what the weak links are. I never bought a mustang for fuel economy, I used the extra fuel consumption as a reference. I fill my car daily and notice any fluctuation in fuel, as I drive the same way daily. 120 to 135 to work, and 85 to 90 on the way home depending on traffic. I have no problem buying a set of used 295/50s for the back every month or few weeks.
  14. RMRJR

    RMRJR Member

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    The bushings do not control total timing they control the mechanical advance in the distributor. Total timing is the mechanical advance in the distributor combined with the initial which is controlled by how far you crank it around. The spring combination controls how fast the mechanical advance comes in. MSD recommends locking the distributor out the FBO bushings are a better option. As you stated you can crank the distributor to the moon and advance the total timing and my car is not driven easy.
  15. v8only

    v8only Active Member

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    the 65 primary jets will b too small...i have less head than u and its happy with 68 jets...try a 68 or 70 jet...

    what size squirter do u have? try at least a 31. id also suggest the cam kit for the holley as that will help with what u r describing

    Sent from my SPH-L710 using Tapatalk 2
  16. lizardsman

    lizardsman Member

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    Ok, I put the heavy silver springs, and the black bushing. I have my initial timing at 18* where it was to begin with. It seems to idle fine but back fires outta the exhaust. And my a/f gauge won't even take a reading, it just flashes 7.4 and when it does show a reading, just briefly its 21 or so then drops to 8 or so and then starts flashing again. Please help!
  17. lizardsman

    lizardsman Member

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    V8only and rmrjr, would you mind telling me what your running for ing, dist and what your running for timing and how you have your dist set up?
  18. v8only

    v8only Active Member

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    crate motor est 325-350 flywheel hp

    msd non vacuum advance dizzy crane ignit box
    lightest dizzy springs with black bushing for 18 mechanical advance..set to 18 initial..36 total

    Sent from my SPH-L710 using Tapatalk 2
  19. lizardsman

    lizardsman Member

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    Thank you. Seems similar, just I have the tightest springs. I will try to change them today, if it stops raining. Would you mind, what's your spark gap?
  20. lizardsman

    lizardsman Member

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    Yes, you do a better job explaining it, now that I've read more and had the distributor apart I better understand, and please don't feel like I was insulting you, I drive my car the way I do, and do not judge people for the way they drive thier stang. So thank you for the insight, as I stated I love info.

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