launch bog gremlin
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launch bog gremlin

  1. #1
    Boat Nut sleekcrafter's Avatar
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    Default launch bog gremlin

    Still fighting the bog gremlin. Seems the batter I make the boat launch, the worse the bog is getting. When I was running a single Dominator, jet extensions helped, blocking the PV cured it. I'm now running a dual carb tunnel ram with two side mounted 1050's. I had fuel pressure issues, that are now solved, and the launch is harder than ever now. The problem is the better the launch becomes, the bigger the issue of bogging is. The first bog is about three seconds into launch, lasts for a second or so, engine loses 100 rpms, then comes back 100%, then 2 seconds later it repeats, the bog for a second, comes alive 100%, then 2 seconds it repeats again. After 4 mini bogs it is 100%. I'm sure it's leaning out, I know fuel is getting there and it's rock steady @ 7psi. Im I past the point where the PV can be used, due to the fuel transfer in the bowl?
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    Senior Member jockorace's Avatar
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    Default

    There have been many threads on this topic. You have your fuel pressure issue solved, however it sounds like a classic case of inadequate fuel VOLUME. Solving that issue starts with your tank pickups and your entire fuel system needs reviewing. Here's a good test (electric pump only) .....remove just one fuel line from one carb bowl, run that one line into a 1 gallon container. Turn on your fuel pump. It should free flow and fill that container in 30-45 seconds. If it can do that you don't have a volume issue. Jocko

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    Boat Nut sleekcrafter's Avatar
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    I've been thru the complete system, -10 to the pump, -10 to the filter, -8 to regulator, (2) -8 to carbs. It's 7 PSI at the carbs, and pump will deliver 12 PSI. The problem is, after lurching forward it bogs, and its almost instant. If you've ever heard the wheel stander cars at the strip, thats the sound and for lack of better description, how it feels on the launch. The PV sits higher than the jets, I'm wondering if they are indeed sucking air? I can run it all day WOT, and not have this issue, only when at hard accel.
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    No Sandbar To Far sanger rat's Avatar
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    Do you have the wedge shape roundy roundy floats?
    Quote Originally Posted by One More Year View Post
    The only blab's I will even be a part of is just when it is me they are talking about. Aaaah yes I can see a few good looking shiny tall deck motors on the beach, with barely enough fuel to get back to the launch saying, "Holy crap how fast you think that Daytona was going man? That's like the 20th time he's gone by today?"

  7. #5
    Boat Nut sleekcrafter's Avatar
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    Quote Originally Posted by sanger rat View Post
    Do you have the wedge shape roundy roundy floats?
    Wedge yes, circle track floats no.... They are wedged for side mount carbs, LH/RH for both carbs.
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  8. #6
    cfm
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    Sleekcrafter - something to look into. I saw a discussion at ST the other day/week that was talking about some Dominators that had one of it's circuits located too high and would become uncovered too easily. Not the replaceable jet (main) circuit.

    That's all I remember, but again, something to have checked out with your carb(s).

  9. #7
    Boat Nut sleekcrafter's Avatar
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    I read that thread, CFM. I have later model 1050s.
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    Senior Member jockorace's Avatar
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    Have you considered (or just to try it) blocking off the PV's and just jet it up? I have never run PV's on any of my blown deals (even the lake boats). Jocko
    Last edited by jockorace; 08-08-2011 at 11:35 PM.

  11. #9
    Boat Nut sleekcrafter's Avatar
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    I'm thinking, this may be my next step. I've got the carbs dialed in nice, except for this bogg issue. No flat spots, stumbles, or hard starts. Guess I'll stock up on more block offs and bigger jets, much easier with one carb! lol
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    Default a little lost here....

    Quote Originally Posted by sleekcrafter View Post
    I'm thinking, this may be my next step. I've got the carbs dialed in nice, except for this bogg issue. No flat spots, stumbles, or hard starts. Guess I'll stock up on more block offs and bigger jets, much easier with one carb! lol
    Can someone explain how a PV works on a boosted engine? I know they're rated at a certain vacuum, and are suppose to open when the vacuum drops below the rated number to compensate the lack of fuel flowing through the main jets. So how does a PV operate on a boosted system that should never see a vacuum?.... I have ZERO experience with carbs on a blower application, unless we go waaay back to the Paxton days on Y block Fords... Sorry to side track your post, it seems you've really done your homework and narrowed your issue down to the "little" stuff....In GREAT detail....
    Ray
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    gn7
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    I don't know why, but I wasn't aware this was a boosted engine. Sleek, Jocko is correct correct. PV have no business in a blown boat engine. Heres why I say that. With a normal carb, with no boost reference in the manifold, and recieve its vac signal from under the carb, itwill NEVER see enough of a vac drop to open the PV. The vac only goes higher, not lower under the carb. If it does drop, its for a split second.
    In the manifold, you will see vac up to a certain throttle opening, then the manifold pressure climbs to the point that the valve is open all the time. With a 4.5 PV, the valve is open with anything lower than that, 4.0, or 3.5 inches, or any boost. Its not hard to run a blown engine a 1.0 " while cruising. So the damn valve is open anyway. You just can't "save" fuel with a PV in a blown boat. Its in boost too easy. Now a street car, thats a whole other story. Because you can cruise at 2000 and the throttle is damn near closed, and the manifold vac is 10"+
    If you have PVs, take them out and jet up about 6 sizes on any bowl that has a PV.



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    Default Blown??

    Bob, maybe it's me that thought incorrectly he had a blower on this thing...Re reading the thread I don't see where he mentioned a blower. Must have been another poster that mentioned a blown lake boat and the absence of power valves...

    Ray
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    Senior Member Scapegoat's Avatar
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    Where exactly is the bog happening in relationship to throttle position. Sounds to me like the carb is having an issue in one/multiple circuits.

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    Default Couldn't be....

    After re reading the thread, could it possibly be as simple as raising the float level a tad? I have very little experience with the new Dominators, but carb function is carb function and if you feel like it's a fuel starvation issue try giving it a little more to play with inside the bowl...Mounted sideways should reduce the chances of "fuel slosh over" thru the vents and stack the fuel against the rear walls of the bowls until the launch tones down a bit....
    Ray
    PS Just a wild guess....
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