Help, ive overfilled carbs with oil

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
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Buddy Holley
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Help, ive overfilled carbs with oil

#1 Post by Buddy Holley » Sat Mar 19, 2022 4:57 am

hi, I've overfilled the strombergs with oil, one about 1/2 from the top and the other all the way to the top. I then realised what I'd done, i then sucked the excess out with a syringe put the black screw cap back on some oil came out from the cap, now i cant remember if i started the car after that, all i know is it won't start now. i understand that the oil can go down the carb throat and into the pistons, my question is will this stop it from starting? Because it started before this and ran before but now its not, will my carbs need cleaning out. I haven't a clue how open them up. Can I just clean the dash pots out or will I need to strip them down and blow through the galleries and clean the fuel bowl with carb cleaner?
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Re: Help, ive overfilled carbs with oil

#2 Post by Charles H » Sat Mar 19, 2022 9:57 am

Ooops! It is actually pretty simple to sort. On each carb, undo the four screws around the edge of the dashpot and carefully lift up the entire assembly. It will reveal a big spring which will also lift off. You are then presented with the sliding part of the carb with a rubber diaphragm screwed onto it. This with the diaphragm will also lift up and away. It has the needle attached to the bottom, so be careful with it! You can then clean the oil away and check that the diaphragm is not split, Replace it if it is in any way perished or degraded. Then it is a simple matter of reassembly. Just make sure that the little raised lump of the diaphragm sits in its recess.
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Re: Help, ive overfilled carbs with oil

#3 Post by Buddy Holley » Sat Mar 19, 2022 10:45 am

Well done Charles I'll try this when the Missus gets back from shopping.
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Re: Help, ive overfilled carbs with oil

#4 Post by pete lewis » Sat Mar 19, 2022 3:16 pm

and a tip if the diaphragms are a bit wrinkled and distorted but have no splits of small holes (thats a need for replacements) a wash in petrol will return the diaphragm
to normal size ,as if swollen it can be hard to reseat them
overfillng should not stop her from starting but as it over restircts the air piston rising it will cause running problems till the excess is displaced
it does just run into the carb throat through the two holes in the base of the air piston and get burnt as you drive cant do any harm
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Re: Help, ive overfilled carbs with oil

#5 Post by Buddy Holley » Sat Mar 19, 2022 4:53 pm

Hey, I've just taken the dash pots off. Ive been careful as Charles suggested taking the dashpots off indeed i found what Charles said I'd find. the diaphragms look a little bit distorted and wrinkled but not too bad, and a little bit of petrol to clean. i have put them back, but one has a two small splits and i didn't check the other one but if im changing one I might as well change the other it does look a bit perished and degraded i noted the nub on the rubber diaphragm and its orientation i haven't started the car, but have put back together for now. I will need new diaphragms It did look a bit mushy in the dashpots when tipped out the oil and there was crud that flowed out as well. Also could the float bowls be gummed up? Can they be taken off insitue or will I need to pull both carbs off? Will the galleries need blowing out or is a case of stripping them if there gummed up or do I need to sonic clean them?
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Re: Help, ive overfilled carbs with oil

#6 Post by Charles H » Sun Mar 20, 2022 10:21 am

The float bowl is underneath and can be unscrewed. If you are getting diaphragms, get a pair of float bowl gaskets too! The needle you have already removed, so in theory, as long as you clean the float bowl and check the shut off needle works, (made of brass and usually perfect, better than replacement ones) then no other special cleaning required.
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Re: Help, ive overfilled carbs with oil

#7 Post by Buddy Holley » Sun Mar 20, 2022 12:14 pm

OK not a problem ordering these parts but the needle is a bit scuzzy. can I sand that with some fine emery paper?
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Re: Help, ive overfilled carbs with oil

#8 Post by Buddy Holley » Sun Mar 20, 2022 12:20 pm

OK not a problem ordering these parts. but are you referring to the needle thats attached to the dashpot? or is that the float bowl shut of needle? its a bit scuzzy. can I sand that with some fine emery paper?
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Re: Help, ive overfilled carbs with oil

#9 Post by Charles H » Mon Mar 21, 2022 8:45 am

Don't emery them, it will change the profile. As long as the shut off needle works, leave it alone!
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Re: Help, ive overfilled carbs with oil

#10 Post by johnnydog » Mon Mar 21, 2022 4:09 pm

Buddy Holley wrote:
Sun Mar 20, 2022 12:20 pm
OK not a problem ordering these parts. but are you referring to the needle thats attached to the dashpot? or is that the float bowl shut of needle? its a bit scuzzy. can I sand that with some fine emery paper?
The rod that is part of the damper that screws into the top of the carb body (with the black top with a 'coin slot' in the middle) can be cleaned up gently with fine emery, although I have never known it to be necessary.
The needle that is at the bottom of the piston inside the carburettor (that goes into the small brass circular jet), as Charles says, must be treated with care and never cleaned with anything abrasive. It is a tapered needle which rises to vary the amount of fuel relative to the speed of the engine and throttle position. They all look similar to the naked eye, but a fine change to its profile can alter the fuel mixture quite noticeably. If you remove the piston, to reduce the chance of any damage to the needle, a convenient place to store it is in the air intake vents in front of the windscreen with the needle through the slots!
The needle (sometimes referred to a float valve) is not a serviceable part, although I agree with Charles' comment about original used valves being far less problematic relative to fuel leakage than new or reproduction versions.
Cleaning out the float boat is a lot easier if the carbs are removed as one unit, and it isn't difficult to do. Whilst upside down, it is far easier to adjust the tab on the float that shuts off the fuel supply to the carbs via the float / needle valve. The blue official workshop manual gives the required gap (can't think of it off the top of my head :roll: )
If you remove the needle / float valve, ensure the same number of alloy spacers under it go back on refitting. It may be worth checking the condition of the rubber O rings on the jet with the float bowls removed. Any replacements should be compatible with modern ethanol fuels to reduce the rubber degrading over time.
If you search (or ask) on here, there will be information about the refitting of the carb top to ensure it is correctly positioned relative to the smooth lifting and falling of the piston which is essential for correct / smooth running.
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