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Stromberg 150 CD flooding


antanol_1238

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Hi Pete et al,

Have just spent another exciting evening in the garage dismantling Stromberg carbs… (why do we do this to ourselves!?!). Here are my findings:

  • Holes in piston towards engine on both carbs. Check
  • Good point about the Smiths valve, didn’t think of that one! I took it away and closed the hole with tejp, started the engine but situation the same even when the engine is warm.
  • Tried to lift the piston a little bit, and it stalls (too weak mixture)
  • Turned down the jet at least one more turn, no change (4 turns down)
  • The engine tends to stall during acceleration, I had the same problem with a Volvo 240 that I had when I lived in Sweden. It turned out to be a small hole in the diaphragm. Checked both of them, but can’t see any holes.
  • Needles are 6H, have not checked this in manual yet, but I assume they are correct (?) since they came in a repair kit that I bought from Rimmers.
  • Air cleaner is original, but it has not been on the engine during these test runs.
  • Springs are fitted in both carbs
  • Choke is thames barrier

Thanks for your help so far chaps. To be continued…

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Take the jet down further till pin lift make a small increase in idle

sound like its far too weak,

 

leaving the cleaner off will make an weaker mix

 

i would fit them back on and drop the jets more turns

 

make sure the needles are fitted with the shoulder flush with the piston base ??

 

 

Needles I make mk1 6j mk2 6ac

 

just doing it on a tablet none of the sites give details , Grrrr on laptop it works

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Hello again...

 

I think I finally found the root cause for the problem... I always try to search on this (and other) forums about a specific problem before I post anything in order to avoid repeating the same Q&A. However, I think the cause of my problems have not been documented here or elsewhere before! When I decided to check the diaphragm I had to remove the aluminum ring and the four screws that attach the diaphragm to the air valve (piston). I noticed that the screws were very loose, I probably assembled them just with my fingers, and forgot to tighten them with a screw driver. When I assembled everything again I made sure to tighten these screws, and I also put some rubber grease in between just to make sure it would not leak. I guess that the air leak was not from the manifold, but actually inside the carb!

 

The engine runs smooth at 800 rpm now, and everything seems to be ok. The only changes I did besides this was to reduce the float distance from 18 mm to about 16-17 mm, and I started with the jets 4 turns down, instead of 3 as in the manual. Despite this, I had to lower the jet one more turn in order to get rid of the weak mixture. So the jet is now 5 turns down from flush, which seems to be waaay too much in my thinking, but I guess it should be that way?

 

Thanks Pete for your never ending patience with us Stromberg strugglers! :)

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Glad you found the culprit and ...owned up to the loose screws Ha , we have all been there at some point

.....what you mean its fell off , ive just done that up....didnt I !!!!!!!

 

The turns is not cast in stone , its a starting point to get in to start,

once hot twiddle till the cow come home ,

same applies to SU or any constant depression jet setting.

 

Whilst both makes do a job I still say lay out the strom parts alongside SU

and make you mind up about which is the best bag of bits

 

Pete

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  • 2 months later...

Hi

I have a GT6 and Like several others I've also suffered from fuel leaking from the air filters which can't be good given the proximity of the exhaust. Also, when I drive the car, it drives fine but then occasionally misfires /misses a beat and there is a distinct whif of petrol.

 

I've previously replaced both fuel needle valves and am in the process of replacing them again. This time I have both carbs off at the same time and have noticed a difference between them. If I could find out how to upload images to the site I would but words will have to do. On the underside of the carb inside the fuel resovoir there is a short brass tube at the base of the jet ......and on one carb there is a second short pipe , located on the periphery of the round boss that the needle is mounted in that must be for some reason. On the other carb I just have a hole, no pipe. Is this what is normal? Do I need to do anything about it?

 

Regards

 

Kevin

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there are two slightly different specs for front and rear carbs, generally unless modified only one has a choke starting valve which collects excess fueling from a dip tube in the float chamber 

the other carb does not have a choke and does not have this short additional tube

the non choked carb gets its enrichment from a short  connecting tube between the start valve centre section which feed direct into the non choked throat.

 

 

if you have temperature compensators fiitted remove them and check the adjusting nut inside is making the plunger seat and seal off the air bleed 

this must be closed at normal operating temperatures,  more important its closed or you cant set the idle mixture if its open.

 

the small casting has two o rings to seal it to the case and down its bore. 

 

if in doubt  remove and pug the hole for eternity

 

to close the plunger just turn the small nut a couple of turns till the plunger stays seated ..closed 

 

be ware some  two arm floats will/can fit upside down and this really upsets fuel levels .

 

Pete

 

 

 

Pete

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  • 1 month later...

Hi!

Don’t think I need any more advice about flooding carbs, I guess I just need a shoulder to cry against... My 1966 Vitesse Mk I has suffered from flooding carbs on and off for the last year or so. Sometimes I have had it running for a short while, no flooding, and now it’s back… This is a common problem for all cars with strombergs, and we can find lots of information about root causes and corrective actions on the internet. Yet, this problem pops up again and again on this and other forums. Why?

I have spent the last week trying to get my Vitesse back on the road again, but these flooding carbs just won’t stop flooding. Here’s a list of what I have done:

  • I have dismantled and re-assembled the carbs at least 10 times (lost count…) and done every thing according to work shop manual.
  • I have taken cleanliness to a new level, frequently blowing with compressed air, even using magnifying glass when searching for small rubber contamination (from hoses) etc.
  • Fuel pressure is max 2,1 PSI given the fact that I bought an expensive HUCO pump. Just in case, I have also added a pressure regulator…
  • Carbs have been rebuild with “new everything” about a year ago. Not much mileage since then unfortunately…
  • Floats are correct type, not upside down
  • Gaskets are correct type.
  • 18 mm float distance. Check!
  • I started the HUCO fuel pump and let it pump fuel into a can for a while just to clean the system before attaching the hoses to the carbs.

The only thing I can thing of now is:

  • I have new needle valves, but they seem to be of poor quality. New parts can be bad parts these days.
  • I have read that one can tap the needle valve with a hammer just slightly to make them seal better. Which I desperately did. Was that a mistake? :o
  • Floats are leaking and have fuel inside (they seems to be ok…)

My plan was to keep spannering tonight and tomorrow since I have and MOT appointment on Monday, but I have replaced that with barbeque and drinking wine instead. To drown my sorrows.

Cheers,

Roger.

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tis unfortunate you are having so much fun, it matters not a jot  strombergs or SU  they all seem to suffer from float problems and valves not sealing

 

yes a light tap on the needle is an old idea ....it used to work. dont bludgeon the thing to death in a rage of spleen venting enthusiasm.

 

SU had a Grose needle available with a ball seat but even these have fallen into the  aftermarket unreliables. many wont stock them now.

 

really ( more wine ) its only valve. float, debris, pump there's little else to tackle and you have the Tee shirt for perseverance  ...it seems

 

    dont know what else to suggest 

 

one thought .....this is spilling fuel from the  small round  vent  port on the front filter face ????   or somewhere else ????

 

there are many versions of float bowel gasket some leave an opening for fuel to pour out under the chamber 

 

 

    all the best  Pete

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Pete,

Thanks.

I think I got the preservance T-shirt about three decades ago (!) when I was a poor student from a very remote island stubornly trying to drive my Herald 13/60 Saloon in Stockholm during rush hours among taxi drivers in much modern cars (with little success, I can tell you a lot of stories from that time… ). ONE Stromberg will give you some trouble, TWO will not give you TWICE the problems. You get 16 TIMES the trouble with twin carbs. At least… The good news with all this problems, is that I just kissed my beloved 13/60 bonnet and told her that I will make her look good again, and I will never cheat on her again with those lousy Vitesses… These cars listen to what we say, I’m sure. They definitely have a soul.

I think I have to write something in the thread “old age”…  I had problems finding contamination in the carbs without magnifying glass…

Pete: Please write a book about Stromberg Carbs…  You will make a fortune

PS.  will try to send pictures of flooding tomorrow.

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there's always been a love hate relationship with constant depression carbs be they stroms or SU , i just say strip one of each and look at the component 

parts, its easy to see the stroms win .  whether its a single or twin matters not a jot

and on the assy line in the day would have been set to a pre arranged mechanical setting of throttle stop and jet height , bolted on and they ran, no messing with balancing or colour tunes  etc.  if the  T. plates are both in the same set place it will be balanced well enough.

both are pretty simple things just needs a few basics to make them work,

by design stroms are a fraction more economical, but if you need to twiddle SU has more aftermaket needles to try

both have their foibles and advantages 

 

there.s  plenty of  books and with my typo's and spelling would get banned so probably give it a miss  !!!

    there's a book called the Commer Story , me and my family are in there quite a bit, 

have been twiddling stombergs since we have had Hunters and Avengers in the family since the late 60s,  most of the clues

I try to advocate come from various examples of misguided enthusiasm so you build up a reservior of events you come across

I did run an emmission dept for trucks and vans for many years so there's some background in stick to the basics

and having the Audit and warranty under my wing we had to know a lot about everything, so in the back of the grey stuff is 

clues range from dry seal screen rubbers to piston rings, bearing tolerances to crownwheel mounting distances 

 and Commer Walkthru to Renault Magnumas we had to audit  the whole truck  range and design over 42 years 

 

is this a thing for old age page  !!!!

 

anyway where's your leakage coming from  ???????

Pete

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I know this might sound silly but spend a couple of quid on fleabay buy some new hose. If it only removes one potential issue of rubber contaminants then it has to be worth it. For me both mine were dripping fuel and just changing the hose sorted the problem. Maybe I was just really lucky

 

Aidan

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