Stromberg CD150 fuel leak

[Robin]

More advice needed!

 I had a heater problem on my vitesse which is now fixed but in order to do so I had to take the twin CD 150 carbs off and the inlet manifold. I put everything back but noticed a small drip coming from the copper tube on the front carb and this poured out once the engine was turned off. I didn’t. Do anything the carbs when they were off the car so it may be just co-incidence and I hadn’t noticed as the copper tube would be covered when the air filter box is on. Any thoughts as to what might cause the petrol leak? 

[NonMember]

Do you mean the copper pipe with the flange in the upper right hole of the air filter face? I think that's the float chamber breather, so any fuel coming out there suggests your float valve is stuck open, or the fuel pump pressure is too high.

[Robin]

4 minutes ago, NonMember said:

Do you mean the copper pipe with the flange in the upper right hole of the air filter face? I think that's the float chamber breather, so any fuel coming out there suggests your float valve is stuck open, or the fuel pump pressure is too high.

Ok  thanks - I’ll check the float valve as a starter

[Pete Lewis]

definitely the float chamber vent port

if you disturbed any fuel hose there is a good chance refit has presented you with the dreaded rubber sliver ,bit of hose gets cut off when you insert the metal tube

this then floats about in the pipe work and ends up jammed in the back of the float needle assy 

good site for pretty picture is    https://www.buckeyetriumphs.org/carburetors

ignore its aimed at TR the basics are very similar .

Pete

 

[Robin]

50 minutes ago, Pete Lewis said:

definitely the float chamber vent port

if you disturbed any fuel hose there is a good chance refit has presented you with the dreaded rubber sliver ,bit of hose gets cut off when you insert the metal tube

this then floats about in the pipe work and ends up jammed in the back of the float needle assy 

good site for pretty picture is    https://www.buckeyetriumphs.org/carburetors

ignore its aimed at TR the basics are very similar .

Pete

 

Pete - if I just want to check the float chamber with the carbs out of the car is it just a case of undoing the 6 screws and lifting it off or do I nee to take the piston out first as described in the article?

[NonMember]

You should be able to remove the float chamber with the piston (and jet) still in place.

[Pete Lewis]

agree just the 6 screws ,unclip the float ,  unscrew the float needle valve  , crank over or use pump primer to flush a small amount into a jar

if the float has two valve arms its easy to fit it back upside down ,this would mess up fuel heights

Pete

 

[Robin]

So can I take the float chamber off with the carbs still on the car or do I need to take them off again

[Pete Lewis]

its easier with the carbs off but have a try just the 6 bowl screws and gently pull the chamber bowl down , dont tear the gasket 

the bit where you need to be an acrobat is the float and its valve are under the main body and vision is not as easy as on the kitchen table  

the needle valves have a variety of af spanner sizes can be a faf getting a size and fit 

just go steady , 

Pete

[Robin]

7 minutes ago, Pete Lewis said:

its easier with the carbs off but have a try just the 6 bowl screws and gently pull the chamber bowl down , dont tear the gasket 

the bit where you need to be an acrobat is the float and its valve are under the main body and vision is not as easy as on the kitchen table  

the needle valves have a variety of af spanner sizes can be a faf getting a size and fit 

just go steady , 

Pete

Thanks Pete - think I’ll remove the carbs to make it easier

[Pete Lewis]

its a pain but thats probably best , you can  then find or not find anything .  

Pete

[Paul H]

I modified an old 1/2 ins spanner , shortened and ground the top and bottom edges to remove the 4 nuts easily . Makes removal and refitting much easier . I’ve got the T shirt for rubber slivers due to fake R9 tubing . The coloured tape is to make sure the spanner goes back in the tool box which I carry in my Vitesse 

Paul 

[Robin]

2 minutes ago, Paul H said:

I modified an old 1/2 ins spanner , shortened and ground the top and bottom edges to remove the 4 nuts easily . Makes removal and refitting much easier . I’ve got the T shirt for rubber slivers due to fake R9 tubing . The coloured tape is to make sure the spanner goes back in the tool box which I carry in my Vitesse 

Paul 

Thank Paul

[NonMember]

17 minutes ago, Paul H said:

The coloured tape is to make sure the spanner goes back in the tool box

I wish something as simple as coloured tape would ensure my tools went back where they belong!  😛

[Colin Lindsay]

Do you remember that rubber coating stuff - Plastidip - that was about years ago? I bought a tin of yellow and dipped a few tools; almost thirty years later the coating is still good. The reason I chose yellow was to identify my own tools if anyone borrowed them...

[NonMember]

29 minutes ago, Colin Lindsay said:

 The reason I chose yellow was to identify my own tools if anyone borrowed them...

My dad was a freelance TV sound engineer. All his cables and stuff were marked with a dob of ugly pink to identify them. Well nobody else would choose that colour!

[Robin]

I’m going to check the float chamber for debris - how do I check if the floats are solid or hollow as this seems to affect the float height.

[Pete Lewis]

as far as i know all strombergs have  a solid float it has to float it cant sink  

tip the carb upside down and it should   be 17/18mm gap between the float and the casting ( the float will be at an angle ,  measure the shortest gap)

just  bend the float arm to adjust the gap

and any deris blocking the float making  a flood will be under /behind the valve i wont be passed through it so whats in the chamber doesnt matter that much

need to unscrew the valve , and also give the supply pipes a squirt into a jar either by crank over or prime the pump lever if you have one 

see if you catch a tiddler 

Pete

[johny]

Yes Robin a pic is worth a shed load of words and there's some good ones of all this in the free to download workshop manual. Believe you can also get reprints in paper....

[Colin Lindsay]

24 minutes ago, Pete Lewis said:

as far as i know all strombergs have  a solid float it has to float it cant sink  

Maybe they should have named that ship 'The Strombergic'... 

[dougbgt6]

I thought they were hollow, I thought I'd heard of one punctured/split somewhere on here?

However, unlikely to be the gap suddenly causing the problem, it's the dread slivers. You mark my words!

And you've got them on the bench, haven't you? So turning over or priming ain't gonna do it, you're gonna have to blow!

Doug

[Robin]

Hi All 

Quick update - took the carbs off, cleaned out the float chambers and valves and everything now seems ok - no more petrol leak. But I’m now after some more advice...

I ‘v just noticed that the piston on the front carb sits flat but on the rear carb the piston is raised slightly ( see photos). Also, when I raise the piston on the front carb, there’s no affect on the revs but if I raise the piston on the rear carb it cuts out straight away. There’s also a more pronounced ‘hissing’ on the rear carb which I assume is air being sucked In?

Any thoughts as to what I should do?

thanks

 

[Robin]

And this shows the ‘hissing’ from the rear carb

[Robin]

Not sure if this is relevant but the rear carb piston raises about 3mm before the front carb piston starts to raise when accelerating. Should both pistons raise at the same time?

[johny]

Yes this needs sorting out as both pistons should sit flat and rise together. If you lift the piston with a finger (engine off) it should drop back down with a clunk. Mine didn't and it was because the needle wasn't centred in the jet. Once you have this correct it sounds like the carbs should be balanced to make sure the same airflow is going through each one.