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Discussion Starter #1
We finished the build and installed the engine into the boat. Now we're trying to get the engine to idle. Can a blower motor idle at 1100 to 1500?

We can get the engine to idle at 2500 to 3000 but anything under that and it stalls

Here is what we working with,
6-71 blower running -8.3 underdriven on a BBC 515 with 2 Holly 4150 850 Mechanical secondary carbs. No chokes. Power Jets blocked off. Jetted 72 primary 70 secondary. Fuel pressure at 7 lbs. MSD 6al box 6k pill w/ MSD Marine Dist. Timing at idle is set at 20° advanced (ran smoothest at this point), 32 total. When I gun the engine, the timing doesn't move past 32° total.

Plugs were soot black. Electrode was tan. Insulator base was black.

Can a blower motor idle at 1100? Am I wasting my time trying to achieve this? I know once I install the pump and get it in the water I'm going to loose a few hundred RPMs but at 2500 to 3k I'm asking for a no wake ticket.
 

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first thing to do is swap the pulleys ,if your going to underdrive a 671 u sould use it as anchor, #2 set the timing at 30 and lock it in
 

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Discussion Starter #3
Will do. we talked about this last night with Kyle. That will make it +9.1. Pacman How about a lower Idle. Is that attainable?
 

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Lord of the Drinks
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My motors are similar to that build. Mine idle at 1,000RPMs, no problem. Mine are happiest locked at 30 degrees, but I had to put start/retard boxes on, as I was going through starters.

I think you may have some carb setup issues. Sounds lean? Where are your idle mixture screws at?
 

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Mine is at about 950 out of gear and 800 or so in gear. I have a outdrive boat so it has to be shiftable.

My timing is locked out at 30 degrees and I had to use a high tq starter. A 6:71 on 500+cubic inches is not going to do much, but I don't think that is your idle problem. Is it surging?
 

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IMO, ur running those carbs very lean, especially with the pv's blocked off...u should be at least 80 squared to start & work from there...set the timing as mentioned above or a little more 32-36*...i see no reason why it wont idle at 1k...also...if u overdrive the blower that much, ur putting alot of strain on parts for longevity...its not a race boat!!!!:)...just my .02 cents, but, what do i know :)

FastRat
 

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Discussion Starter #7
Thanks for all the suggestions. I started to swap the pulleys but decided to keep it under driven and as an anchor for now:D HH was right about the carbs being a off. I finally thought about this like I would on my Quads. I jetted up to 79 primary then 78 Secondaries. Then adjusted the idle circuit or the screws on the side of the metering block. I opened them up to 2 turns out then the engine smoothed out. I didnt block out my MSD yet but after I snugged the dist up and started the bitch up she purrred:)devil She is stubborn but after a little tinkering it fire right up.

I know if I keep tinkering I'll get it all figured out. Just atap of the peddle and that engine come alive. I hope its like that in the water
No surge but she runs real nice where its at.
Again thanks for all the advice. I'm one happy Mo Fo:)devil
 

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What are your air/fuel screws at? The serge you hear in a blower motor is a rich condition,not that thats bad hell serge is cool turn the screws in for less serge out for more.Good starting point is all the way in and 2 turns out if the carbs are stock and the air bleeds have not been played with! I agree with the locked out at 30*!And I always square jet with no PVs.www.skagenboats.com
 

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If you have an MSD distributer, You can put a bushing in it for your base Idle timing. I run mine at 15 degrees advance idle and 30 degrees total advance at 3000 rpm's. blower 15% overdrive. Idles at 1000 in neutral, 7 to 8 in gear idling in a v-drive. Starts and idles like an old Chevy Caprice !!!
 

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mo balls than $cents$
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Thanks for all the suggestions. I started to swap the pulleys but decided to keep it under driven and as an anchor for now:D HH was right about the carbs being a off. I finally thought about this like I would on my Quads. I jetted up to 79 primary then 78 Secondaries. Then adjusted the idle circuit or the screws on the side of the metering block. I opened them up to 2 turns out then the engine smoothed out. I didnt block out my MSD yet but after I snugged the dist up and started the bitch up she purrred:)devil She is stubborn but after a little tinkering it fire right up.

I know if I keep tinkering I'll get it all figured out. Just atap of the peddle and that engine come alive. I hope its like that in the water
No surge but she runs real nice where its at.
Again thanks for all the advice. I'm one happy Mo Fo:)devil
cave, lock your dizzy before goin much further. if you tune the carb now at idle, then lock the dizzy, its gonna idle high again;) lock the timing as suggested, there's no reason for a mechanical advance in a blown boat imo.
 

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Jimmy with all that work you have in this motor.Don't run it lean fatten this thing up to at least 82's or 84's squared.Are you running a pyro on #7 cylinder?Number 7 and #4 will be the lean cylinder's.Go fat on the fuel mixture.Rather be to fat than to lean and melt it down.One more thing i'd like to see ya run the carb pressure at 8 psi not 7.


Jim S
 

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Lord of the Drinks
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She is stubborn but after a little tinkering it fire right up.
Sounds like you have it figured out- congrats.

If I peddle mine while cranking, I run the risk of it popping back through the carbs. Mine start best by tapping the gas, then cranking it over- there is a small delay (while that gas gets through the blower), but it fires everytime.

There's a fine line between fat and happy (surging) and lean enough to idle in gear without a surge or dying. Mine even surge differently sometimes depending on the weather...lol.

Time to get her wet. :)sphss
 

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Jimmy with all that work you have in this motor.Don't run it lean fatten this thing up to at least 82's or 84's squared.Are you running a pyro on #7 cylinder?Number 7 and #4 will be the lean cylinder's.Go fat on the fuel mixture.Rather be to fat than to lean and melt it down.One more thing i'd like to see ya run the carb pressure at 8 psi not 7.


Jim S
i agree. new carbs & motor , no idea if it's gonna lean out at wot.get a pyromiter on motor! you only lean out too much ,once! the jets do seem small
 

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Discussion Starter #15
Jim I don't know If i can run the sensor in the Gill exhaust I have. I'll call Gill Marine on Monday. They do have a flat spot on the bottom that looks like a boss where I can tap the sensor in. #4 did look lighter in color than the rest. Here is a pic of the headers.



I'm getting dam good at removing them bowls. I'll richen the carbs up today. I just bought 2 Holley jet kits for just over a Franklin. I cant run them square just yet. I'll bump it up to 84 primaries 83 secondaries for now Jim. I'm kinda hesitant to pull the dist out again. I've never done a lockout before. I read its easy but every-time I read how easy stuff is it turns out to be that I have the one whatever that seams to be Un-eazy. I'll take a look at it today.
 

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Hey Cave, cool you got that thing running. (pretty sweet btw)
Just for referance I am running 84,s in my carbs. My timming is locked down at 28. Locked down at 30 shouldnt give you any problems starting it. What dizzy are you using?
 

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Discussion Starter #17
MSD Pro Billet Marine Dist.
I'm excited to say the least. Getting this all together in a few months was rough. I'm close to getting the Liberator wet. I was going to install the jet pump today but after reading all the replies I think I may just have to reevaluate the pulling the distributor out and locking it out.

84 jets in Canada. Inst it cold up there? How man months do you get to put that Hallet in the water?
 

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Cantard
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MSD Pro Billet Marine Dist.
I'm excited to say the least. Getting this all together in a few months was rough. I'm close to getting the Liberator wet. I was going to install the jet pump today but after reading all the replies I think I may just have to reevaluate the pulling the distributor out and locking it out.

84 jets in Canada. Inst it cold up there? How man months do you get to put that Hallet in the water?
I have been following your build, You do nice work.
Pro Billet.... you can do it. I can send you the steps if you want.

Our summer,s are probably not so very different than yours. Average days are in the 80,s low 90,s I would say.

I get to boat for 6 and have another 6 to think of all the things I could do to it. This winter it is locked up in a storage unit that doesn't open the doors again till April. Getting smarter.:D You cant imagine the projects you will start when boredom kicks in about the middle of January.

You get to hit the water year round or do you have a cold season aswell?
 

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Discussion Starter #19
Summers @ 110 to 115° Fahrenheit with 90% Humidity in July through mid September along with the Monsoon storms that pop up in minutes. I can boat all year long. The winters if you can call them that here are in the hi 70s to mid 80s. Mornings are colder from 40 to 60°:D burrrrrrrr:D

I got the images from MSD just a few minutes ago. It reads easy. I'll do it today.

Ok here it goes. Re jet richer and lock out the dizzy at 30°. Hope I can start her up at 30°
 

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Cantard
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Summers @ 110 to 115° Fahrenheit with 90% Humidity in July through mid September along with the Monsoon storms that pop up in minutes. I can boat all year long. The winters if you can call them that here are in the hi 70s to mid 80s. Mornings are colder from 40 to 60°:D burrrrrrrr:D

I got the images from MSD just a few minutes ago. It reads easy. I'll do it today.

Ok here it goes. Re jet richer and lock out the dizzy at 30°. Hope I can start her up at 30°
It will start and prob clean up your idle a bit too. Just an extra tip..... before you pull the gear off mark it then after you lift the top and flip it put the gear back on 180 from where it was, not a big deal but to be all scientific if you don't it will be off half a tooth.


And ya, its hotter were you are.
 
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