Stromberg gushing

[66 Alpine]

Looking for suggestions- 66 SV
I noticed a slight smell of gas on the last drive-
Decided to install the Petronix kit I had purchased previously and diagnose Gas fume smell one weekend.
After install, I crank it over and gas is POURING out the bottom half in back (Where I can’t see it) of one of the strombergs and dropping right on the manifold.
Yikes…
just a bowl/float gasket or time for a full rebuild?
if so, it’s beyond my patience; any referrals appreciated!
Must say I’m leary even post rebuild; that they will need tuning just to get her started, let alone running smoothly- of which I have no experience with!
Many Thank

 

[Acollin]

First off- obvious : do not drive the car with gas falling onto a hot manifold.
Decide next if tackling a diagnosis / repair is what you want to do and are capable of doing. I have found that with basic tools manuals and guidance from knowledgable people, the job of dialing in the Cd 150s was straight forward.
A rebuild or a repair is doable by the “shade tree“/ hobbiest mechanic.

Diagnosing the problem. You will probably need an assistant ( turn the ignition key) and a way of looking 360 degrees around the carb. I assume it is not leaking when the car is not running. With the car cranking— not starting- you should be able to expose the leak. Probably best to inhibit a start by disconnecting the coil, but be extraordinarily careful to avoid any sparking with uncontained fuel flying around.
mirrors , a camera, raising the car to improve the viewing—- you need to find a way of putting eyes to the problem. Personally, I would not go a rebuild route without a better understanding of the problem — Especially if the car was running good before I discovered the leak.
gas “pouring“ out should be pretty easy to detect and to me suggests something has come loose or become plugged as opposed to malfunctioned.
think, too, about pictures of the leaking once you find it. This will help the helpful provide the best path for the repair.
Hope this helps— I am sure more knowledgable folks will chime in too.
keep us looped in
good luck
Andrew

 

[hartmandm]

What Andrew said ... plus if you still have a plastic fuel tee in between the Strombergs, it might have cracked.

Mike

 

[Tim R]

My guess would be that the plastic T Piece has split (like dozens of others have since they started adding ethanol and other rubbish to the petrol).
If it were me I wouldn't waste any money on getting Strombergs rebuilt. They go out of synch regularly, constantly need topping up, split diaphragms for fun and are generally a pain.
I would spend the money on the curved inlet manifold and twin-choke Weber set up that Alpine Innovations sell. We have this on two of our Alpines, it makes the car smoother, faster and with much better acceleration. The bonus is that it pays for itself in the massively increased fuel economy. Once fitted you will never need to touch it again, it is literally fit and forget.
Tim R

 

[hdar5702]

I would avoid cranking the engine, the starter motor can produce a spark.My Alpine has the manual primer on the fuel pump.I would use that to find the leak.You may need a 'friend' to help with this.

 

[66blues]

My Weber conversion was the best thing I did for my Alpine. Just make sure to get the full kit which includes the new linkage, and intake, not everybody sells the complete kit.

 

[alpiner]

While I totally respect the reasons and decision why Sunbeam Alpine enthusiasts install the Weber conversion, I am an advocate for the original twin Stromberg carbs. Maintaining, tuning, and fussing with the CD carbs has kept me smiling on many weekends in the garage. The workshop manual, forum information, and lots of other resources
give even the most inexperienced owner the knowledge and tools they need to keep the carbs tuned and car running smoothly. For me its the pleasure of working on the carbs that is the reason I own a classic Sunbeam Alpine V. No judgement intended, I'm just and old school guy who loves spending time tinkering with his car.
Good luck in solving the gas leak. Lots of good advise on the Forum.

 

[Acollin]

X2 on alpiner’s comment. I would like to keep my car as close to 1966 as parts availability will allow. The carb tuning is a huge part of that. I ,too, am a tinkerer and probably enjoy the wrenching as much as I enjoy the driving.

 

[Thor 1211]

Looking for suggestions- 66 SV
I noticed a slight smell of gas on the last drive-
Decided to install the Petronix kit I had purchased previously and diagnose Gas fume smell one weekend.
After install, I crank it over and gas is POURING out the bottom half in back (Where I can’t see it) of one of the strombergs and dropping right on the manifold.
Yikes…
just a bowl/float gasket or time for a full rebuild?
if so, it’s beyond my patience; any referrals appreciated!
Must say I’m leary even post rebuild; that they will need tuning just to get her started, let alone running smoothly- of which I have no experience with!
Many Thank

Once in a while I have had the carb overflow because of a stuck float and a sharp rap on the side of the carb cures it. It could be crud in the needle assembly, a bad float or wear on the float hinge, but, for me, the long term solution is to take off the carb, clean everything, test and then adjust the float and maybe replace the needle if the tip looks worn.

I don't share the complaints of others regarding Strombergs. For my money, they are quite reliable, easy to tune and perform reasonably well. However, they are 60 year old technology and many a classic car owner has given them up because there have never been very many guys who know how to work on them.

 

[am99ey]

On my SV 1966 the worn ring seal in the jet assemblies caused petrol dripping and final leaking/gushing ..
New seals solved the problem.

I am happy with my two CD150's . After cleaning and renewing the seals they work great.
The joint of the sync clamp of the throttle axles had slipped randomly due to worn threat in the small screw. A bit tricky to find out about. This resulted in irregular idling and acceleration. After fixing it, the problem disappeared.

 

[Hodee]

You may be able to fix this leak with just a few dollars and minimal time. I had a similar leak and it was the o-rings on the needle. Unscrew the needle from the bottom of the bowl and see if the o rings are in bad shape. Replace with Viton orings of similar size. fuel will come out but prepare with a catch rag. Reinstall with caution to be sure the needle reinserts easing into the center. There is a centralization procedure but I found if i was careful upon reinstal, that wasnt always necessary. My leak was fixed quickly , easily and for very low cost. I am no expert on setting and tuning the Strombergs but it worked for me. Good luck.

 

[66 Alpine]

Thanks for all the great info- I finally broke it down (and with an assistant), found the gas leaking from behind the flange behind the intake filters-
The front and rear photos of the flange attached- looks like a threaded plug on the front, but gas coming out the back. Backs of both carbs identical- Thoughts? Thanks to all-

 

[husky drvr]

Thanks for all the great info- I finally broke it down (and with an assistant), found the gas leaking from behind the flange behind the intake filters-
The front and rear photos of the flange attached- looks like a threaded plug on the front, but gas coming out the back. Backs of both carbs identical- Thoughts? Thanks to all-

Just some thoughts,

The plug is more like a "freeze" plug - no threads.

A quick perusal of the WSM didn't reveal a clear picture of those passages, but the open one is probably the fuel bowl vent to atmosphere - the other a vent to the diaphragm chamber.

The bad news is there is NO fuel passage higher than the top of the jet/needle outlet.

If you are having fuel flowing out the hole behind that plug, then your carbs are flooding.

Possible causes are improper adjustment of float level.

Faulty needle valve and seat.

Bad float that can't close needle and seat.

And lastly, excess fuel pressure that defeats the needle and seat.

Those are the items you should check.

There might be other issues, I'm not that well versed on the CD's. Hopefully someone else can chime in with more knowledge.

Hope this helps,

 

[bernd_st]

I can second to the gas flooding statement. Had gas coming out that very same plug on a friend's car and it was the float valve not properly shutting, because one of the float valve axle holding legs in the gas chamber broke off (weak spot of the CD's). So carb off and disassembly time ...

 

[66 Alpine]

Thanks for the quick reply- I did clean the fuel filter recently, hand primed with lever afterwards- see any possible issue there? I’ll

 

[66 Alpine]

I can second to the Gas flooding statement. Had gas coming out that very same plug on a friend's car and it was the float valve not properly shutting, because one of the float valve axle holding legs in the Gas chamber broke off (weak spot of the CD's). So carb off and disassembly time ...

Much appreciated- anything else that I should replace while I’m in the float chamber?
Thank you

 

[rixter]

This is how bad it was with the carb on my series 5 (with later Stromberg CDSE), when I first got my car. In my case I had to do a full cleaning of the tanks, the lines and carbs as they were loaded with debris.
Rick

 

[bernd_st]

Much appreciated- anything else that I should replace while I’m in the float chamber?
Thank you

There isn't much except the float and the fuel valve. Check whether the valve Is shutting off properly once the little center pin is pressed down. Check it by blowing into the fuel line inlet while holding the pin down. The chamber seal needs to be renewed as well, of course...

 

[chryslerwagon]

What Andrew said ... plus if you still have a plastic fuel tee in between the Strombergs, it might have cracked.

Mike

plastic tee after the fire

 

[66 Alpine]

Thanks for the help-