Results 1 to 7 of 7

Thread: Vanguard Mod thread posted on other forum

  1. #1
    Member
    Join Date
    Jun 2007
    Location
    FAI
    Posts
    2,294

    Default Vanguard Mod thread posted on other forum

    FYI I posted some questions, and successes, on mounting a bigger Backwater Performance Carb on a Vanguard Mud Buddy. Not sure how many of you have shallow drives, and have thought about doing the same thing. Maybe what I found will make your lives a bit easier. It is in the powerboat/modifcations forum.
    If the instructions had been more clear, I could have done this in way less time. But, if I can get her to run smooth, that is behind me.
    Good luck this fall, and watch out ducks,
    ARR

  2. #2
    Member AK375HH's Avatar
    Join Date
    Apr 2006
    Location
    Wasilla
    Posts
    610

    Default

    I'll be interested to hear what your gains are from this.
    It's not skybusting if you fold em'.

  3. #3
    Member
    Join Date
    Jun 2007
    Location
    FAI
    Posts
    2,294

    Default

    Still needs a bit of tunning. I see about 1mph gain, up and down river, with the heavier load. Out of the water she over revs and the limiter cuts out the motor to protect it. In the water, the load keeps the rpm down. I need a tach to better gauge if I have the right prop on or not. The gain is a rough number, and like I said, I need to do a bit of tuning on it. She seems to run ok, but not crisp.
    She will run better when I do the muffler mod, and then the ported/polished heads w/ one piece stainless valves. On paper I should gain, on the low end, better than 7hp, and hopefully 10hp.
    When I finally got to talk to the tech, he said that carb really should not be used without the performance muffler. Wish they would have told me that, I'd have done it first. I did find out how to mod my muffler. I'll have some cost in welding, but it will be well less than the $420 they want for the aftermarket muffler.
    ARR

  4. #4
    Member mikelee26's Avatar
    Join Date
    Jan 2016
    Location
    Texas
    Posts
    5

    Default

    You are going to notice the most significant difference with the upgraded heads (IE decked, ported, and polished). You can pump as much fuel and air into that motor as you'd like, but it isn't going to do much with stock heads. Your current motor I can guarantee you is operating at at least 60% blow by (meaning the valves are not seating and allowing blow by). This is how the vanguards come from the factory(according to Van Guard 65% is acceptable, SMD), and if you have ever gotten stuck and heated her up it is probably closer to 85%(which where mine was at prior to installing heads from boat dr). You will notice the most significant difference from upgraded heads. Top speed will remain about the same but your load carrying capability will increase drastically as well as holeshot. I installed the the Mikunni HSR 42mm if I am not mistaken, and notice a decent difference once adjusted correctly I.E. the acc pump and jets. Holeshot increased and top speed may have increased 1-2 MPH. I gutted my exhaust and seen maybe a MPH or two.

    I have all the adjusted settings if you would like.



    96.jpg101.jpg

  5. #5
    Member
    Join Date
    Jun 2007
    Location
    FAI
    Posts
    2,294

    Default

    Mine is the little 23hp vanguard. It works well on the 16'x52" boat. Don't really want to add weight w/ a bigger motor. If I can get more power out of this one, then it might be worth it. I knew I was taking a chance doing the carb first. Likely I should have done the exhaust first to help it breathe better. Likely I'll do the same thing you did and gut the exhaust instead of buying a $450 hotrod exhaust. The heads should help a lot. If running 4500rpm or more they suggest the 1:5:1 roller rockers too. I just did not want to put $2K into this motor right now, and, it is hunting season, so figured I'd look at it this winter or next year.
    I think I got the 34mm Mikuni. Don't quote me on that though,
    ARR

  6. #6
    Member mikelee26's Avatar
    Join Date
    Jan 2016
    Location
    Texas
    Posts
    5

    Default

    I have experience with them as well. Do a leak-down test. You will be surprised with how much blow-by you have.

  7. #7
    Member mainer_in_ak's Avatar
    Join Date
    Sep 2008
    Location
    Delta Junction
    Posts
    4,078

    Default

    Not only do these mods void your engine warranty, they're not the best option. In our cold weather environment, EFI has shown the greatest gains in power and cold weather reliability. You can thank Stu Varner, the Go Devil rep over in fairbanks for his pioneering work on EFI. Before any of the big companies ran EFI, he tested it first here in Alaska. He was the first guy to test open loop and closed loop EFI systems. Give him a call before monkeying with your carbs.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •