The saga continues - carb overflow

[Bruce Palmer]

I originally thought that was the problem until I saw the bent float. However, it seems that my original float was flowing poorly before failure - the car had a difficult time starting. Now, the new pump, I start with no problem - barely even need to choke, so I assumed the flow was pretty healthy.

Seeing how much gas pooled (and stained!) my driveway, fair to say the new pump is working well!

Now I'm getting confused. How was your float bent? What caused that?

How was your original float flowing poorly? What does that mean?

Just a guess based on the "clues" given.... The float level was raised during the "un-bending" of the float which resulted in a rich conditon, resulting in easy starting due to fuel level being too high. I'd say new fuel pump has nothing to do with ease of starting, unless it is putting out too much pressure which we have seen with stock pumps. This in turn could over-power the needles and seats holding them open.

Where is the "pooling on the ground" gas coming from? out of the bottom of the carbs? Out of the aircleaner, out of the mouth of the carbs?

[rdefabri]

Bruce,

Bear with me - I am no expert, let alone SU-savvy!

I had previously taken the floats off. My original fuel pump was dead, but I didn't realize it at the time. I took the floats off to see if any gas was getting to the carbs. There wasn't any, and I must have used too much force putting the floats back in. I am talking about the "arms" that suspend the float - there is a central tab that closes a valve that I assume suspends fuel flow until the gas level in the bowl recedes. These arms were bent, so much so that the central tab was not even making contact with the valve.

When I bent the float arms back to a point where the central tab touched (and actuated) the valve, the car worked perfectly.

So, originally, after installing the new fuel pump, the car was spurting fuel from the overflow tubes that exit the back of the air cleaner. Coming out quite a bit too - that caused the pooling on my drive way. As I said, once I fixed the floats, this stopped immediately.

I do agree with you that a fuel pump would have little to do with starting - but my guess is that the original fuel pump wasn't doing much, effectively leaning out the mixture.

I can say this, the car hasn't run this well since I've owned it. Only things I changed were the fuel pump and the correction of said bent floats.

My apologies for the terminology - I don't know the SU carb as well as I should, but all seems to be ok now.

[Bruce Palmer]

You might want to purchase a copy of our JUST SUs VHS or DVD to have in your tech library. Four hours of fun filled action packed info, guaranteed to tell you more than you ever wanted to know about SU carbs. Basically good comfort level discussion of what things are and what things do and how they inter-relate to each other. I've heard back from many customers about how the magic of SUs has been cleared up with this piece.

We now return you to your regularly scheduled programming......

[rdefabri]

Do you guys do Jag SUs as well? I am assuming YES, since they are close enough...

I know the ZTherapy reputation is fantastic - and I have been meaning to obtain some of the materials you have...FOUR HOURS?? Wow, that's in depth!

[Bruce Palmer]

Actually, between you and me, it's more like 2 hours of the nuts and bolts info and 2 hours of stuff the previous owner thought was pertinent to the topic but in my estimation is just excess info. Akin to continuing to write a book long after the bad guy has been caught, tried, convicted, hung, and buried.

The Jag carbs are doable. We've already got a Healey set of 2' SUs on the schedule for this winter when things will hopefully have settled down some...

Edited August 18, 2008 by Bruce Palmer
Didn't answer the Jag question

[whamo]

Bending the tabs affects the float chamber fuel level. As bruce pointed out , this affects the fuel mixture. Assuming that they are the same as before is a heck of a leap of faith in my opinion. If you didnt allready, you should set/check the float level setting. If it is set too high or too low, no amount of mixture adjustment on the carbs will get you where you need to be mixture wise.

[rdefabri]

There's no chance they are as original, so I agree with you there. But remember, I didn't bend the tabs, only the arms that suspend the float from the bowl cover.

My primary concern was stopping the spewing of gas - I did. The car now runs well, very well. I would bet with proper adjustment (as I suspect it NEEDS), it would run even better.

One of my first posts on this board was about how sluggish my car was. I have a 4.11 rear and a later model 5-speed. Another board member said my car should be a rocket, and it wasn't. Since the "adjustment", it runs great - still no rocket, but it's much better. I would think with proper adjustment, there would be much improvement.

That's work for another day

[whamo]

They make the most power right before you burn a piston.