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Carbs are good for you

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Old 06-24-2016, 03:58 AM   #1

Brian Belcher is currently offline
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Default Carbs are good for you

I thought I'd keep y'all up to date on my restoration/preventive up keep.
First thing; isn't it said I hate using the pooter cause it doesn't have auto correct like my Iphone. I actually willchange the word cause I can't spell it !!

Onto the boat.
The last weekend was great. The boat, Mermaid Dreams (my granddaughters trump all votes),did OK. Had carb troubles. The choke hot wire from the alternator had come off again and it was running super rich. DUH !
Top speeds were 33-34mph but I had 5 adults of which 3 were in the 240 pd range and the others were in the 130`160 range. also had my two granddaughters, 5 and 7yrs old. 125 gals of fuel and 25 gals of water. My wife had three GIANT coolers full of food so 33mph and a 7250pd boat, I'm happy.
BUT !!!
The choke situation has been on my mind so I sat down for five (5!!!) hours and read up on how the mysterious spread bore worked. It is a complicated piece of art work.
I am pretty handy with the Holleys but the spread bore was always avoided because of the complexity.
What I discovered with our carbs.....
The choke MUST BE COMPLETELY OPEN for the back barrels to function. The choke actually closes off the circuit that allows for them to work. So, simple way to test yours.
Take the cover and spark arrestor off so you have an unobstructed view of the choke plate over the front two barrels.
Turn the ignition key to "RUN", do not start !! Your buzzer should be going off for low oil pressure but that is fine.
NOw watch the choke plate. It will take a few minutes for the electric choke to heat up enough to slowly start opening the plate.
You may need to lightly push the plate to simulate air flow from the engine running. The plate should be completely open after 4 minutes. Try opening it all the way with your finger and it should stay open, COMPLETELY !!
I think I've made it clear on how important the before mentioned is.
Next thing I learned about the spread bore is the idle speed adjustment and idle mixture are intertwined. you must first get your mixtures screws set at 2 1/2 turns from seated. Next, start it and set your idle speed at 650 rpm. If you have a vacuum guage, now is the time to adjust your mixture screws for the best vacuum. If you don't, start turning them together, in 1/2 increments. Watch the tach for increases in idle rpm. If they do go up, adjust the idle speed screw and keep it at 650 rpm.
The goal is to have the idle speed screw as close to being closed as possible so that the idle mixture ports are being used for idle speed and not the so much the idle speed screw.
There. That sounds as clear as mud.
I must brag that i"ve got our boat is purring like a kitten. I haven't had a chance to go run her but MAYBE this weekend, I can slip down to a local lake, Lake Maumelle, and go run her with all four barrels.

I now have the carb for the genset off and cleaning it up.
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  • Old 06-24-2016, 03:56 PM   #2

    Shabah93 is currently offline
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    Default Re: Carbs are good for you

    Very nice write up for members running carbs. Thank you for taking the time to write it.

    BTW, my daughter is also a mermaid nut. She loves anything mermaid.
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    Old 06-24-2016, 11:22 PM   #3

    Brian Belcher is currently offline
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    Default Re: Carbs are good for you

    Be a real man and let her name it ! LOL
    I told my wife and daughter in law that any name the granddaughters picked was fine, as long as it didn't have "fairy" in it.
    First name the youngest GD picked ?
    yep
    "Fairy Princess Unicorn Ship"

    I told her that that name was already taken
    BTW They named my old jeep buggy "Chitty chitty bang bang

    UPDATE
    I forgot to add that the hot wire from the alternator falling off---I slightly crushed the barrel fitting to tighten up the fit. It takes a ittle effort to get it off now.

    Last edited by Brian Belcher; 06-24-2016 at 11:26 PM. Reason: cause I'm scatter brained
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    Old 06-24-2016, 11:48 PM   #4
     
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    Default Re: Carbs are good for you

    Nice! What year and model merc do you have? ( assuming its a mercruiser)
    Im going to try this long weekend coming up, thanks for sharing!


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    Old 06-24-2016, 11:52 PM   #5
     
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    Default Re: Carbs are good for you

    So what happens if your choke isnt opening all the way, would it be a hard fix?


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    Old 06-25-2016, 12:05 AM   #6

    Brian Belcher is currently offline
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    Default Re: Carbs are good for you

    Mine is a 1997 7.4(454ci) Gen VI, Bravo III. It has the Thunderbolt V ignition. As you guesswd, it's carbed right now but fuel injection is it's future. I'm good with Holleys but our's don't have them. They are a Weber/Carter and I have to admit, they are good carbs. I'm just more comfortable with fuel injection. I can make an FI system sing. Give me a 2 bar MAP and an ADAL/OBII and I'm happy.
    I don't know nearly enough about tese engines to say "expert" but I am pretty good at researching !!
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    Old 06-25-2016, 12:16 AM   #7
     
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    Default Re: Carbs are good for you

    So most mercs are electric chokes? Is it true ive read some guys during the summer season do away with chokes all together, they say you can wire the choke "open" no need due to not having to cold start. Not sure if that would be the right thing to do. [emoji12]


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    Old 06-25-2016, 12:38 AM   #8

    Brian Belcher is currently offline
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    Default Re: Carbs are good for you

    You could loosen the three phillipshead screws on the choke and turn it counter clock wise till your choke plate fully open. BUT, you will zero choke and cold starts COULD be a biatch. Better plan would be to let it run at idle for a good 15 minutes and check that the plate completely open. If not, with those screws loosened up, turn the choke housing CCW till it is full open. Remember to tighten (UNloosened) those screws up!!!
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    Old 06-25-2016, 12:42 AM   #9

    Shabah93 is currently offline
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    Default Re: Carbs are good for you

    As soon as we make our maiden voyage I will let my girls name the boat. As of now the outdrive is off and I'm aligning the motor output shaft and gimbal bearing. Bought the boat last weekend. Waiting for a few more parts to come in before I can put it back together.
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    Old 06-25-2016, 01:30 AM   #10
     
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    Default Re: Carbs are good for you

    Quote:
    Originally Posted by Brian Belcher View Post
    You could loosen the three phillipshead screws on the choke and turn it counter clock wise till your choke plate fully open. BUT, you will zero choke and cold starts COULD be a biatch. Better plan would be to let it run at idle for a good 15 minutes and check that the plate completely open. If not, with those screws loosened up, turn the choke housing CCW till it is full open. Remember to tighten (UNloosened) those screws up!!!


    Beauty! Thanks again!!!!!


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