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Thread: Fear Factor

  1. #1
    As I thrash my way through this boat, with 16 weeks left, I have some fears. When I call Good Vibrations, the young tech guy tells me that mid throttle operation is unattainable, with mechanical fuel injection. I find that hard to believe. I'm fairly handy and have seen boats run at what appeared to be a midrange operation. Before I buy carbs, are there any reassuring comments on the midrange capabilities of old style injection systems. I would like to be able to idle (briefly) and be able to run 2k to 4.5k for a long period when necessary. I could have put this in Gear Heads but I'm looking for v drive answers.

  2. #2
    O.k. First. What injector are you going to run?
    And this is blown or unblown?
    Describe what you have.

  3. #3
    Fiat, it's blown 8-71, 467 BBC on gas at a little less than 8:1. I'll run it mostly on AV Gas. I just don't wnat to have to put it in the water and either idle or haul ass. There are times when covering some ground is good.

  4. #4
    and what injector?

  5. #5
    An Enderle birdcatcher with an 80 pump.

  6. #6
    You will get a cycling at idle. If you try to clear that cycling (motor going up and down in rpm) with barell valve adjustment then you will get a lean spot...a cough or backfire through the injector when the throttle is opened suddenly. have to live with that idle surge.
    Part throttle as Endlerle has designed will be fat. It will cruise fine...just be fat. It's hard to hold a steady throttle as the butterfly area is big and all it takes is a wiggle of the toe to speed up.
    The injector wasn't made for part throttle cruising much. But that does not mean it is that bad and it can be made better.
    Start with a 29 nozzle. 130 pill installed in the barrell valve as Enderle does originally. If a used injector...make sure it is a gas injector and not alcohol. If it is alcohol...don't panic. Just a few changes are in order to make it work on gas. Do not plumb in a high speed check valve at this point.
    Make sure the brass bypass can has a light tension spring in it with no shims. It should be about a 2lb check.
    Fire the motor and adjust the barrell valve position as needed. Lengthening the linkage makes the idle richer. Shortening the linkage makes the idle leaner.
    Adjust the linkage slowly...a couple flats at a time. Lean the thing until the surging starts to go away. Then richen it 2 flats from there. A quick yank on the throttle and check there is no hesitation.
    Take it for a run. If you feel a hesitation in the throttle opening with a load on the motor...then simply give the linkage another flat in the rich direction. Play with the barrell valve adjustment till you get the best idle...and no hesitation.
    There are things you can do to help lean while cruising. But start out this way. Many things you can do with constant is just a matter of adjustments and bypasses. But you need to tune the wide open end before working the part throttle end. Then I can tell you many, many ways to make the injector better at smaller throttle openings.

  7. #7
    I had pretty much the same set up and cruised the boat all over.

  8. #8
    Thanks Fiat. It sounds like I can live with a fat midrange, its hard to leave it there anyway, sounds like one can clean it out if necessary. Since its winter, I'll get a bunch of extra tuning parts for the early summer. Thanks.

  9. #9
    It won't be that fat at cruise when you get close to the main jet required overall. It will just be on the fat side. If it is black smoking at are way off on the main jet. You could wind up with as large as a 150 for a main jet. All depends on the blower, combo etc. 130 will be safe to start. Small nozzle makes a better high pressure system...better for cruise.
    My boat on alcohol does fine at part throttle. Just so damn throttle sensitive.
    If blower speeds are kept down and boost low...smaller nozzles can be used. Like I say...many things one can do. You could even put in a manually operated bypass fuel when a button is held down. This along with the right barrell valve adjustment can make a surge free and smooth idle...for no wake zones....but don't ever hit the throttle with the button down or bye bye blower.

  10. #10
    I would like to try something new (injection) but it sounded like the young fella at Good Vibes was taught to not guarantee injection at anything less than WOT. Nothing ventured, nothing gained. More questions in a month or so, particularly on primer systems and no wake zone applications. Thanks.

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