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Thread: Float Height

  1. #1

    Default Float Height

    Hello
    I have an older (~1979) small Chrysler 4 HP outboard engine which is running pretty poor and only with the Choke activated, especially when getting warm. I beleive the fuel-air mixture is too lean and therefore I wonder if the carburetor float height is properly set at correct float height.
    The carburetor has a couple of stamps in the metal - "LMB" and "200"
    I hope you can help

    Thanks
    Anders

  2. #2
    Join Date
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    Default Re: Float Height

    Usually the float height on most Chrysler/ Force carbs (other brands too) is,
    when the carb is upside down the float is level with the body.

    Usually poor running is from water in the fuel, or the carb is dirty, or the fuel pump(if you have one?)
    The tank on top can corrode and rust/gunk can get down to the carb, install a small filter in the fuel line.

    The jet is the screw that holds the bowl on, makes sure the holes are clean and the bowl is clean.

    The reeds behind the carb, if damaged?? they can contribute to poor running.

    Clean the carb, check the reeds for broken, missing petals.
    Reset the air screw.
    Start at 1 and 1/2 turn out.
    Then adjust from there.
    88 Bayliner with 2002 225 HP Mercury EFI

    Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
    ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

    In Scenic , Beautiful San Sebastian by the sea Florida

  3. #3

    Default Re: Float Height

    Hi Jerry
    Thanks a lot for your swift reply.
    I'll dismantle and detail the carb for cleaning as you suggest, and reassembly and adjust as adviced.
    It already has a small plastic fuel filter inline with the fuel line going to the fuel shot-off valve, but today I purchased a new filter in clear plastic for easy visible control in the future.

    I'll get back with an update and results when I'm done

    Cheers
    Anders

  4. #4
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    Default Re: Float Height

    That is a old tillotson carb you should be able to get parts at your local ma and pop lawn mower repair shop. The high speed jet is in the bolt that holds the float bowl on. The float must be level with the carb when you hold it upside down. Remove the float to bend it do not put finger pressure on the flaot needle and seat.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  5. #5
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    Default Re: Float Height

    Quote Originally Posted by andlassen View Post
    Hi Jerry
    Thanks a lot for your swift reply.
    I'll dismantle and detail the carb for cleaning as you suggest, and reassembly and adjust as adviced.
    It already has a small plastic fuel filter inline with the fuel line going to the fuel shot-off valve, but today I purchased a new filter in clear plastic for easy visible control in the future.


    I'll get back with an update and results when I'm done

    Cheers
    Anders
    There should be a strainer in the fuel tank part number F521811. Pull the fitting off the tank and see if it is in good shape if not replace it and install new fuel line. Do not use a inline filter they restrict fuel flow too much and you can cook the piston.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  6. #6

    Default Re: Float Height

    Thanks for the hints. I've found the strainer in the parts catalogue. Will check and clean it or replace.

    Cheers
    Anders

  7. #7
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    Default Re: Float Height

    If the tank is dirty also pour a bunch of steel BBs in it with some engine oil and slosh it around. Once it is clean you can pick them out with a magnet.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  8. #8

    Default Re: Float Height

    Hello again
    Today I took the engine apart and cleaned the gas tank, fuel line and carb. I found a lot of dirt and also a little bit of water. Even in the carbs fuel bowl I found small residues of dirt.
    There was an old grey-plastic in the fuel line which i replaced with a new clear plastic one (did note you comment about reducing the fuel flow, ut I think it is better with an inline filter and at the same time take a notice of spark plug electrode color: black/brown/darkgrey = ok). The fuel tank strainer looked fine and was also cleaned throughly in gasoline.
    I checked the float height with carb bottom-up. It was very close to level, so I decided not to make any adjustments. I did check that it would open and close the fuel valve when moving down and up.
    Also I did remove the "flywheel" and checked the points gap when open. I noticed a small marker at the center axel and adjusted the points gap at the position where the points slider aligns the marker. (I checked with a screwdriver on the piston that this is approx TDC point). I did not have any specs for the gap so I assumed that aro. 0,02" (0,50mm) would do.
    Also I checked the spark plug and wire. Wire and cap looked fine and almost new with no corrosion inside. Sparkplug also looked new with no combustion deposits, either on the electrode or inside the spark plug. As I did not have the specs I adjusted the electrode gap to approx 0,0275" (0,7mm) which I guess will do fine.
    Did set the carb bowl screw to 1 and a half turn out.
    Did also set the other horizontal adjustment screw to 1 and a half tur out (I guess this is the idle speed screw a the other fuel bowl screw is the high speed fuel mixture adjustment?)

    Tomorrow I will give it a try and start it in a bowl of water. Adjust and fine tune when hot and cold.

    I hope my little old Chrysler will behave and become a great worker getting back and forth when going fishing here at the Danish coasts - see map link
    https://www.google.dk/maps/place/930...06!4d10.486346

    Will get back tomorrow with an update on how it goes

    Cheers and thanks for your valuable inputs!
    Anders
    Last edited by andlassen; 09-23-2017 at 03:34 PM.

  9. #9
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    Default Re: Float Height

    The inline filter is just redundant and not necessary if the tank is clean and the strainer in good condition. Adjust the slow needle in a barrel of water in gear after the engine is fully warmed up. Slowly turn it in 1/8 turn at a time until it stumbles and back out for a nice smooth idle. Wait at least 5 seconds between adjustments for the crankcase to stabilize. Make sure the choke is fully open.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  10. #10
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    Default Re: Float Height

    IF??? your still getting fine particles of dirt even when the tank strainer is in good shape???
    Then get a fine particle filter and put it inline.
    Just putting any filter in line will help but a fine particle 10micron will stop the tiny pieces.
    OR?? Remove the tank and strainer and reseal the tank with fuel tank re-sealer.
    I'm sure you can find something in Denmark to seal the tank.
    A filter won't restrict anything if the system is clean, now if you had a fuel pump and was drawing through a water/fuel sep filter and a strainer and hose?? then it might restrict the flow.

    The strainer is just that a strainer and allows the little stuff through.
    Also check the fuel jug for water and crud.
    My neighbor has a 30gal fuel tank for filling his boat, it somehow always ends up with water and crud no matter what he does.
    So far this year he's paid me 95$ to clean out the water and crud from his mower.
    88 Bayliner with 2002 225 HP Mercury EFI

    Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
    ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

    In Scenic , Beautiful San Sebastian by the sea Florida

  11. #11
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    Default Re: Float Height

    Water is the major issue with our outboards. Ethanol is playing a big part now if you do no have access to ethanol free fuel. Either way allways run the carbs dry of fuel between uses keeps the carbs clean and if you keep the fuel tank full of fuel it will eliminate water intrusion during storage. A fine micron filter will plug up faster and it will create a lean condition possibly scoring the cylinder walls and rings. These engine have been running just fine for over 60 years without a fine micron filter. Nothing can replace regular maintenance. If you want to add a filter by all means do so I am saying it is not necessary with regular maintenance procedures.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  12. #12

    Default Re: Float Height

    Hello again.
    Thanks for your valuable comments and hints
    Today I put the engine in a bowl of water as you can see on the photo. It started up almost right away, after a few times pulling the string for priming the carb with gas.

    Click image for larger version. 

Name:	Chrysler 4HP -1.jpg 
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    A week ago it wasnt that easy to get started, so Im sure all my effort cleaning and flushing really paid of

    I shot a short video showing how the engine idles and run fast, with and without propeller load. Its not yet perfect but Im Im getting there.

    https://youtu.be/I515kAC3bi0

    At the end of the video it show that it has a little difficulty increasing rpms when the propeller is in gear.

    Later today I installed it in the boat and went for a small trip around the marina. In situ with propeller and boat load it struggles getting into gear without stalling. Ofcause higher idle rpms when engaging the gear and propeller prevents it from stalling, but then you hear a loud "clonk" and the engine shocks. It shouldnt be like this so I wonder if the ignition timing is set properly. If I remember correctly (from having the flywheel off), adjusting the timing was not an option - you can only adjust the breaker points clearance (which I set to 0,5mm = 0.02"). The Speed lever rotate the whole timing board advancing/retarding the timing depending on rpms. I am running on Octane 95 gas, which perhaps is a little high for an older engine, but this is the lowest I can buy (few places has 92 octane, but its actually 95 content). I beleive the octane influences the ignition timing.

    Well, it is definitely running much better than a week ago and I guess I just have to be patient and try over and over again until it is perfect - as perfect as you can expect from an old vintage engine

    Looking forward to your comments

    Thanks
    Anders

  13. #13
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    Default Re: Float Height

    Cleaning the small passages in the carb might help, the air screw is it smooth and comes to a nice point?
    Try resetting it?

    Idle should be about 750-800 rpm's in gear.
    88 Bayliner with 2002 225 HP Mercury EFI

    Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
    ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

    In Scenic , Beautiful San Sebastian by the sea Florida

  14. #14
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    Default Re: Float Height

    I cringe when someone revs a engine up in neutral. Never go past high idle speed in neutral, do your high speed test on the water in forward gear would like to see that video. It takes alot less fuel to run without a load on the prop. It is the same as running low on oil you will score the cylinders and possibly damage the bearings.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  15. #15

    Default Re: Float Height

    You have a point. I didn't remove all the parts and screws etc. from the carb housing. Did remove the idle screw and float housing, float and nozzle. A quick examination of the parts was done, but perhaps I should take it apart one more time and examine the parts more closely. Also I could clean all parts and housing with airpressure removing any tiny particle remains. I only did the flushing in a bowl with petrol.

    A few years back I did a rebuild of the 4 bbl Holley carb on my old 67 V8 Mustang. I purchased a rebuild kit with all gaskets, needles, nozzles etc. It was actually a very easy job to do with great results and great engine performance, both reg power and milage. Also it was very easy to adjust. The old V8 engine was also set to an idle speed of aro. 7-800rpms. Did not hesitate at all when jumping the gas pedal with auto in "D". Did even spin the right rear wheel leaving a 10 feet burn strip on the asphalt

    As the "FK10098 - Repair Kit" is no longer available perhaps I should order the individual parts and gasket set, and rebuild the carb completely.

    Well, for now I think I will do with further cleaning and adjustment, and then see how it goes.

    Again thanks for your valuable feedback

  16. #16
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    Default Re: Float Height

    Probably one of the simplest carbs all you need is float needle, seat and gasket and the seal for the float bowl. Pull the emulsion tube and clean it wit a small copper wire and then soak the carb in carb cleaner. I blast the circuits with high pressure water after the soak and then blow dry with high pressure air. Put a small bead of thread locker on the threads of the emulsion tube after you shine a light through the tiny holes. Like I said you can probably get the carb parts at your local small engine repair shop.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  17. #17

    Default Re: Float Height

    I know what you mean and the high speed was only very short time which I beleive should not be a problem for a solid engine.

    I did use the Forum menu for entering the video link above and it works fine for me. Anyways here is a direct link I hope will work https://www.youtube.com/watch?v=I515...ature=youtu.be

    Yes you are right - the best way is to do the adjustment in situ with the boat sailing. I did it on my own yesterday and my little 8,5 feet glassfiber dinghy will not level out causing the engine having a hard time pushing the boat and engine not reving at high rpms. Actuallt the boat+engine setup works best with 2 or 3 persons onboard. So i will just have to do it again inviting a friend for nose weight and leveling the boat

    Thanks for your comments and inputs

    Cheers
    Anders

  18. #18
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    Default Re: Float Height

    I always make a new carb gasket when mounting a carb and lightly surface the flange on a glass table with 220 grit. Just pull in one direction only until it shines the same.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  19. #19
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    Default Re: Float Height

    Another thing to check adjust whenever you pull the carb is engine sync between throttl opening and spark advance. On the throttle cam is a is a mark you want the throttle butterfly to just begin to open as the mark passes center of the follower on the carb. It looks like you loosen the bolts holding the throttle cam to the magneto plate and adjust the position of the cam when the mark on the cam lines up with the throttle lever on the carb (follower).
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  20. #20
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    May 2010
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    Default Re: Float Height

    Make sure the screw holding the bowl on, is clean/clear as it's the main jet for the carb.
    Individual parts are available.
    88 Bayliner with 2002 225 HP Mercury EFI

    Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
    ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

    In Scenic , Beautiful San Sebastian by the sea Florida

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