i have a question i hope can be answered today

i have a stromberg on a 2.25 engine. the carby is in reasonable condition as is the engine. recently the accelerator pump failed and i put a carby kit through it and everything was fine. However, it has always run quite rich, it used too much fuel and as soon as i looked at the choke it flooded/fouled. I put an adjustable main jet in last night hoping to fix this problem.

when i wind the needle all the way in, the car still runs all through its rev range, and is still too rich (but is slightly leaner)?? with the needle out 1-2 or even 3 winds it doesn't seem to have any effect. in both cases there is no real difference to the performance of the vehicle and it doesn't belch black smoke???

Any ideas

Cheers

Ben

when you say it doesn't belch black smoke does it blow black smoke at all,what are your spark plugs like what colour, Is the air filter restricting air flow,did the kit have a base gasket although i think if it is sucking air it would be running lean.

no black smoke at all. spark plags are black but not wet...too rich. new base gasket fitted when carb replaced.

Is the mixture needle undamaged? If there is a ridge on the tapered bit from overtightening, it will cause those symptoms,

Cheers Charlie

try dropping the float level a tad

Does the stromberg have a screw in power valve plunger (early type) or a plunger that is pushed in then locked in place by several punch marks around the spring plate (later type)?
Regards
Andy

g'day all

chazza, the mixture needle is new and i have been carefull to not overtighten. i pulled it out and checked it and it seems fine.

lewy, I set the floats to the lowest level from the holden manual 11/16ths=17.4mm...opposed to 5/8ths=15.8mm

Rangy01, sorry i am not sure will pull the top off the carby and look tomorrow.

I still can't understand how the thing can run with the needle wound in all the way?? let alone so well(but rich)?? the only thing i can think of is that when the needle is wound right in, the passage (jet) is not fully blocked (it didn't appear that way when i installed it) or that the power valve may be at fault...but if it were running entirely off the power valve wouldn't it run very very poorly.

any more clues, really appreciate the help

It seems no car shop in Hobart stocks stromberg mains any more. all i wont is a 0.050 main....old cars geezz

Do you know what size jet you have in the carby at the moment ?

I would guess that it must be quite a large diameter to allow fuel to flow past the needle, if the needle is wound fully home.

Jack

no i dont know what size the jet is, but it came with the adjustment needle as one kit. However, it is quite large, maybe a 0.065 jet. It is tapered to accept the needle as it is wound in

Cheers

AFAIK, it should be possible to cut the flow of fuel through the main jet by screwing the adjustable needle fully home. As Chazza says, you do sometimes see a worn ring around the needle, caused by it hitting the lip of the jet, when the needle is adjusted all the way in.

If you have screwed the needle fully in and the vehicle does not notice the difference, I would say you have the wrong jet or at least need to re-evaluate the fitting and how it is meant to work.

I've got a Stromberg with an adjustable jet in my Dodge and just like the idle mixture screw, you can adjust it so that the engine runs smoothly but screwing it in or out from that point, causes the engine to falter. I think I've got a 60 jet in the Dodge, but can't check as I'm a few thousand miles away ATM.

Would it be possible to add a pic of the adjustable main jet fitting ? I've got one at home that is different to others I've seen and though I've pondered over its operation, can't fathom how it was meant to work - wonder if yours is the same ?


Jack

P.S. BTW I thought it worth mentioning that if you can't fix the problem, I would recommend reverting to an original Landy carby ie a Zenith or Solex. I think the former is less complex and the one on my Landy (2A) returns about 22 mpg on a run. If they are in good shape, these carbies are a very acceptable fitting.