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Stromberg 150 on a 13/60


Pdv

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Hi aĺl

Engine will not fire up.

Fitted all new electrics, points plugs etc and new fuel pump.

Electrics fine as strong spark at plug.

Fuel pump working fine as checked fuel at the pipe entering the carburettor and fresh fuel lnto carburettor float chamber. 

The engine with this carburettor used to start first time but has not been started for a couple of years.

Fresh fuel not  e10 into an empty tank so no contaminated fuel.

Diaphragm is in good condition and all moving parts sèem to move freely.

Manual says to tune the carburettor the engine has to be warm, so that's a lot of help.

I am obviously missing something basic, but am at a loss as to what.

Also bought some Easy Start and the engine fired but did not run, so assume that the plugs are working OK.

Any help would be much appreciated.

Thanks 

Steve 

 

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Has the carb been worked on at all? Or has it been sat for a couple of years with stale fuel in it? If the latter, it's probably gummed up and will need dismantling and cleaning. It's not a hard job on Strombergs. When you put it back together (so we're now at the former case) you need to set an "initial state of tune", which is all they ever got at the factory. Wind the jet up to flush with the bridge, then three whole turns down. That should certainly be good enough to get it started on choke, and then warm it up for final adjustment.

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"Easy Start" is good stuff, I believe in Australia it's called "Start ya Bastard!"

If it's trying with Easy Start timing and spark are near right, but if not started for a long time the manifold gasket may have deteriorated. This was my problem, Easy Start made it try, but an air leak at the manifold and you've got little chance.

Doug

 

 

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Hi non member

It has been sitting dry and garaged so it may not need cleaning, and as I  said it all seems to all move OK, but something is not right so I will give it a clean and set it up as said. Was hoping that the manual would have said about an initial state of tune.

Thanks 

Steve

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10 hours ago, Pdv said:

Was hoping that the manual would have said about an initial state of tune.

Actually the official WSM does - I checked it to remind myself whether it was two or three turns - but it's fairly well tucked away in the text.

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12 hours ago, Pdv said:

Fuel pump working fine as checked fuel at the pipe entering the carburettor and fresh fuel lnto carburettor float chamber. 

Did that include direct observation of the fuel level in the float chamber? i.e float chamber reomved for inspection?

I'd be guessing that an uppermost cause of non-start after work on fuel lines is an obstructed needle valve in the carb due to general detritus or rubber shards. Easy diagnosis but does involve removal of carb and partial disassembly. If carb has not been apart in years then a new float chamber gasket will be needed on reassembly.

Does throttle air valve fall with a nice click on to the bridge? If not, and the top cover has been removed recently and all is clean, slacken the four retaininng screws  and gradually and sequentially retighten, repeatedly checking for free fall of the valve.

 

 

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with the air clear off lift the stromberg/Su piston  and let go it should drop qickly with a nice clunk as it bottoms out  

if its stiff then  raise the jet adjuster to be level the jet with the top of the jet holder

now centralise  the jet  undoing 1/2 turn (the bigger nut) drop the piston and give the jet a light tap  test the drop gives a clunk

nip up the big nut 

from flush drop the jet adjuster  3 turns  (( often 2 is enough) top up the dashpot with engine oil 

either make  do make sure the choke is fully operating by su dropping the jet  and CD the ramp does block the intake  on CDS the choke valve is rotating 

that covers most of the basics , nothing difficult 

make sure the diaphragm is located and the two holes in the piston do face the engine

if the diaphragm is wrinkled a wash in petrol will revert it to size 

Pete

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8 minutes ago, chrishawley said:

Did that include direct observation of the fuel level in the float chamber? i.e float chamber reomved for inspection?

That's a bit trickier on a Stromberg than an SU, because the chamber is below the carb and has a big hole in the bottom for the jet adjuster to pass through. Removing it guarantees it's empty.

What you can do, and is worthwhile, is to put a tub under the carb, take the chamber off (five or six long screws), then operate the fuel pump and check that fuel flows all the way past the valve.

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Hi All,

Thanks for your replies, as Pete says the basics are not difficult so it is back to basics.

I have removed the carburettor and will check it all out and set it up as described.

Thanks

Steve

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take care with float gaskets on stroms  as the kits often have a multitude of gaskets they all look similar but some evolution means some corners have changed 

and fit the wrong one and you make a nice leak , so tip is check the one you replace is an exact relpica by shape/contour or it will leak 

you dont need to remove the carb to set most of this up , easier to set the float heght if needed all other settings can be done On car 

 

Pete

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On 10/05/2022 at 10:03, NonMember said:

What you can do, and is worthwhile, is to put a tub under the carb, take the chamber off (five or six long screws), then operate the fuel pump and check that fuel flows all the way past the valve.

That's a good idea, never heard it before. Some repair books (not W.S manuals), give some tips and tricks, though would love a book with all that non official insider Knowledge.

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there are some ideas floating about in the club back room to develop a wiki linked how to we can infill with good ideas  searchable and forum linked 

so Dave keep a watch out this may..or may not develop  

it is just an idea but sounds a good one 

Pete

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