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Blower roll

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Old 05-29-2017, 12:10 PM
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Default Blower roll

Anyway to get rid of it with carbs??
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Old 05-29-2017, 12:24 PM
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Now why would you want to go and do that? Second best thing about blowers on a performance boat IMO, first is belt whine. Now if it's a fishing boat well... I get your point.
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Old 05-29-2017, 12:43 PM
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have to keep adjusting the idle mixture screws and also give the motors as as timing while maintaining your desired idle speed.then you get to do it some more on the water,,I usually strap the boat to the dock.and then you get to play w/ it going in and out of gear.usually for gear change,you turn 1 screw out a little more than the others.
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Old 05-29-2017, 12:57 PM
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You talking about "lope" or "surge" at idle/low speeds?

Several things come into play.

1) Centrifugal timing advance - if your advance springs are letting the weights move anywhere in the "idle zone", then your timing will rollercoaster with the surging, making it impossible to tame. Use springs stiff enough to keep the timing firmly on "base timing" until 1,500 rpm OR totally lock your timing "all the way in". I prefer the first, since hot weather, low vapor pressure fuel, and 32+ degrees of initial timing make for some "hard to start" situations. If you are already a "race fuel motor" then its not as big a concern.

2) Power valves on carbs - if you are not boost referenced, and run higher number powervalves, you can run into idle instability in the carb metering. Boost referencing is recommended on powervalve equipped carbs - and boats don't need PV's in the secondaries, just upjet them.

3) Blower intertia - the additional parasitic drag and rotational momentum of a blower - combined with varying belt tension can be "just enough" to START the surging cycle. If you don't have #1 or #2 contributing to it, it will usually self-dampen the surge out, but if you DO have #1 or #2 contrinbuting, you have a problem.

BUT - I LIKE a little "dependable" Blower Surge. I think it's cool, and it also allows you to time your shifts to ease drivetrain shock.

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Old 05-29-2017, 01:17 PM
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Timing I have Daytona boxes and it set at 16 at idle. 34 total. I mean I can deal with it but I don't like the boat surging at no wake
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Old 05-29-2017, 03:37 PM
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Quote:
Originally Posted by prostockcat View Post
Timing I have Daytona boxes and it set at 16 at idle. 34 total. I mean I can deal with it but I don't like the boat surging at no wake
good ignition box,,time to play w/ the idle screws on the carb.
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Old 05-29-2017, 06:36 PM
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try turning the mixture screws in a tad. What is it idling at RPM wise out of gear?

As for powervalves, even if the power valve was opening at idle, it will have no effect on the idle itself. Powervalves add fuel to the main well, just like main jets do. You boat wont idle any different if you went from 82 jets, to 92 jets. The only way a powervalve will make it idle bad, is if the diaphram is ruptured and raw fuel is being sucked past it.
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Old 05-29-2017, 06:39 PM
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Quote:
Originally Posted by prostockcat View Post
Timing I have Daytona boxes and it set at 16 at idle. 34 total. I mean I can deal with it but I don't like the boat surging at no wake
Are you using the idle stabilization feature? If you are running a custom map, you can email it to me if you like.
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Old 05-29-2017, 06:43 PM
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Will it help with 4-6 deg or more base timing. With good tuning you can tame it down but 90 % of the SC engines I've heard surge. Some patients adjusting air mixture screws certainly help.
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Old 05-29-2017, 07:01 PM
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First startup, locked timing at 36* , no mufflers.

https://www.youtube.com/watch?v=O-fTA0JA36Q

Last edited by MILD THUNDER; 05-29-2017 at 07:04 PM.
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