Set Up Distributor

Automotive powered airboat discussion.
Moritz
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Location: Texas

Set Up Distributor

Postby Moritz » Mon Jan 29, 2018 5:11 pm

Need help setting up a MSD distributor Big Block Check. Have a MSD Pro-billiet Distributor pn 8360. What advance curve should you use. My take is to use the red bussing with lightest sting to give the most advance by 3000 rpm. My thinking is that the more centrifugal advance will make it easier top start, but may make it a little rougher at low RPM s un less you hook up vacuum advance.

Aeon
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Location: Orange county-- the wrong one. I'm in California

Re: Set Up Distributor

Postby Aeon » Tue Jan 30, 2018 12:17 am

Don't use the vacuum advance. Use the lightest springs you have. Play with the bushings to see what one gives you best prop rpm.... Don't run too much total, it's a boat not a car.

Start with 12 and green for 34deg total and work forward. Big cam might want more Initial and depending on what heads I would not go over 36. You might find 14 to 34 or 32 best
You have a built in dyno with the prop,
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

Moritz
Southern Airboat Member
Posts: 540
Joined: Tue Mar 07, 2006 9:57 pm
Location: Texas

Re: Set Up Distributor

Postby Moritz » Wed Jan 31, 2018 7:05 pm

How do other people set there disturber up?

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Deano
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Re: Set Up Distributor

Postby Deano » Thu Feb 01, 2018 11:20 am

Moritz wrote:. . . My thinking is that the more centrifugal advance will make it easier to start . . .

First off, I concur with LadyBackWater and Aeon. Vacuum advance is for fine tuning under a light load that an airboat
will generally never see. Using the lightest springs will allow the timing to come in earlier, which is what you are after.

I comment only because of the way you worded what you wrote.
More centrifugal advance has little to no bearing on how it starts, because . . .
There is NO centrifugal advance while you are cranking the engine to start it.
Look at it like . . . LACK OF EXCESSIVE advance DOES improve starting ability.
Hence, your initial timing setting is what controls how it starts and here that adjustment is made.

You basically have three timing parameters: Initial timing -> timing curve/advance -> Max timing/advance.

Initial will control/influence starting characteristics.
Timing Curve (bushings/weights, springs) will control the speed and size of the additional advance beyond the initial.
Max Timing will equal the initial + the advance. This must be controlled to prevent detonation and subsequent engine damage.

Hope that makes sense, and doesn't add confusion. In the later case, ask more questions.
Like most anything else, it isn't complicated after you understand it. :wink:
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

loudmouse
Southern Airboat Member
Posts: 479
Joined: Tue Jan 22, 2013 3:20 pm
Location: Ocala Fl

Re: Set Up Distributor

Postby loudmouse » Thu Feb 01, 2018 12:37 pm

I set engines up totally different depending on what it wants and what I know from 30+ yrs of tuning them.
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
Built and Tuned by Me
14'X8' JW, Chevrolet 122CID LNF Turbo Engine, Ox box, 80" NGR 3 blade

Life is short, eat your dessert first! :downtown:

Moritz
Southern Airboat Member
Posts: 540
Joined: Tue Mar 07, 2006 9:57 pm
Location: Texas

Re: Set Up Distributor

Postby Moritz » Sat Feb 03, 2018 8:42 pm

Loud mouse how do u set them up

loudmouse
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Joined: Tue Jan 22, 2013 3:20 pm
Location: Ocala Fl

Re: Set Up Distributor

Postby loudmouse » Sun Feb 04, 2018 12:36 pm

Not enough information to say what would be best. Each engine combination is different. The way the boat is set up and driven is different. Too much timing too early causes detonation and you will beat the bearings out of it. What works on a car is not the best for a boat with a prop and high engine load. The whole engine prop gearbox and tuning goal has to be considered. Before any timing is turned up the CARB MUST be right or engine damage is going to happen. A common result from bad tuning on an airboat is dropped valves and hammered bearings. A tell tale sign is high engine temp while cruz in or a rapid climbing temp when u get on it. With A happy tune the temp gauge will stay very consistent with temp about 5° to 10° over thermostat rating.
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
Built and Tuned by Me
14'X8' JW, Chevrolet 122CID LNF Turbo Engine, Ox box, 80" NGR 3 blade

Life is short, eat your dessert first! :downtown:

Moritz
Southern Airboat Member
Posts: 540
Joined: Tue Mar 07, 2006 9:57 pm
Location: Texas

Re: Set Up Distributor

Postby Moritz » Mon Feb 05, 2018 6:20 am

How much play should the distributor have.


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