Ultra-rich Fuel Mixture and Flooding Inlet Manifold Drains

[Nivens]

In my experience I have had several "new" parts which hove not performed properly in service as others have suggested. From the discussion, it seems the carb floats are not controlling the fuel level in the carburetor's fuel supply properly. I would suspect (1) float failure (2) float to needle adjustment, or (3) the needle to seat is fowling so it is not shutting off the flow when the float is full up. Carburetor floats are normally quite reliable, but they can fail in service also. All it takes is a pin hole leak. lf I experienced your situation, I would remove the problem carb(s) and go through the needle and float assemblies meticulously. Make certain everything is clean and everything operates freely. Check the float for leakage (any is unacceptable), check the vents, check the needle setting to be certain the needle is seated fully when the float is raised to the full position. I typically use a blow hose pressurized by mouth to be certain the needle is fully seated and not leaking any air. If everything inside checks out, reassemble the carb(s) on the bench, invert the carb and use the mouth blow hose again to see if there is any air leak by. If so, the float is hanging. That would mean the float is hanging on something and is not freely operating. It could be bent in the hinge, simply the wrong float for the carb, or an impingement somewhere inside the carb float bowl.

 

[Bob_Spidell]

This just came through my FB scroll from 'Dr. Carburetor Alan Vinegar' and is, perhaps, germane to the discussion:

"Not all float bowl lids are the same. Most HD8s use a taller lid and the pedestals inside are taller. As a result the float forks is different as seen in the picture. The previous rebuilder did some nasty bends to the fork and using Grose jets miraculously it worked. I picked up the correct forks from Autofarm who specializes in Healey Parts."

 

[Patrick67BJ8]

If you have the HD type of carbs, you probably only need the jet diaphragms changed. They are a rubber material and crack causing gas to escape through them.

 

[Walter74]

I now replaced the floats, the needle valves, the jet bearings and the jets. Unfortunately no change in the flooding. Mostly the left drain from the air intake is leaking fuel from cold start. I am really lost what to do next….

 

[Walter74]

I mean the left drain of the inlet manifold of course

 

[John Turney]

Does this happen with the choke on, off or both?

 

[Michael Oritt]

Walter--

Reviewing the posts I see from #24 that you added a fuel pressure regulator which I believe you set to 2 psi and that did not help. What kind of fuel pump are you using and can you send a picture showing where/how the fuel pressure regulator is installed?

This topic/problem sure has legs!

 

[Walter74]

Does this happen with the choke on, off or both?

I have the choke cables completely disconnected.

 

[Walter74]

Walter--

Reviewing the posts I see from #24 that you added a fuel pressure regulator which I believe you set to 2 psi and that did not help. What kind of fuel pump are you using and can you send a picture showing where/how the fuel pressure regulator is installed?

This topic/problem sure has legs!

The pump is a Pierburg 06t289. Attached you can find a picture of the Filter King regulator installed and set at 2Psi

 

[Michael Oritt]

Walter--

At this point if this were my car I would remove the Pierburg fuel pump and install an SU.
In any case I hope you eventually get this problem solved and when you do let us know what was the issue and the fix.

 

[johnea]

Maybe fuel find its way around the threads of the float valve. It would fill up the float bowl even if the float shuts off the fuel supply ….

 

[Michael Oritt]

Walter--

Did you ever solve your problem?

 

[Goldie]

When I restored my BJ8 several years ago, we had a similar problem. It turned out that several years earlier not long after I had purchased the car, a Healey shop in southern California had put larger jets in my carbs (this was around 1970). When we rebuilt the carbs several years later (around 2005), the standard needle was installed and too much gas was getting into the manifold. Usually caused flooding and it took a while to figure it out that we needed the standard jets.

 

[Michael Oritt]

Maybe I'm old-fashioned but I feel that if one posts a query and a protracted discussion follows (in this case 50+ posts) "netiquette" dictates that one should keep fellow members apprised of progress and outcome, whether or niot the issue is successfully resolved and even if it is abandoned.

I come here to both gain and share knowledge and I feel it is frustrating to not find out how a problem such as this one was ultimately resolved. In the end it deprives me of adding to my knowledge base and all of us knowing that someone was helped.

 

[MarkWeb95]

Hello,
I have recently revised my BJ7 engine. The engine is running, but with extremely rich mixture. The drain pipes from the inlet manifold are pouring fuel when engine is running idle.
I have checked carbs, timing and valves but everything seemed to be correct. Needles and valve seats are new. Float chamber level is correct. Jet level is also ok. When lifting HS6 piston with the engine running nothing happens to the revs.
I am pretty desperate at the moment, so who can help me solve this issue?

Looking forward to your replies

Excess fuel at idle and no RPM change when lifting the HS6 piston suggests the carb pistons aren’t dropping correctly or the jets are too low (over-rich). Check piston freedom, damper oil, jet centering, and choke return. Also inspect for high fuel pressure overpowering needle valves. A rolling-road SU specialist can diagnose precisely.