Riddle me this: What would 18 psi do to a set of DCOE weber carbs

[Zedyone_kenobi]

Yup, the regulatory plunger in my Mallory pump stuck and I ended up sending 18 psi to my webers for darn near a minute before I realized what was happening. I made a thread over that problem, including the solution.  I am not back to a rock steady 3 psi.

 

However, when I started it up the very first time after this happened the car acted very funny at first. One of the floats was stuck all the way down and I was running on 4 cylinders for a while.  I tapped the top of the carb where the float needle is and the fuel pressure dropped to zero then increased to read 3 psi like it should, meaning it was being held completely closed and empty and when I tapped it, something moved and the fuel started to fill it.  So I have not done anything else YET, but the car does idle a tiny bit rougher than it use to. I have a funny feeling I have done damage to my floats or my needle/seats due to the over pressure condition. 

First I am going to check the float level to see if it has been altered. Something tells me it probably has. 

I am planning on removing the needle/seats and will probably replace them, although I am not sure what will go wrong with a ball and a spring. 

I will examine the floats. Perhaps they will need some adjustment.

 

The car starts fine and idles around 900 rpm very smoothly.  However now I have a slight pop out of the carb at times when I tip into the throttle and under the slightest input of constant throttle I get a pop from the exhaust.  These are new events for my triples, as they have been spot on perfect for 3 years, right up until I tried to make them take 18 psi from my temporarily insane fuel pump.

 

Any other ideas.

Edited May 2, 2016 by Zedyone_kenobi

[LeonV]

Have you checked your float levels?

[Zedyone_kenobi]

yes, I used the Kieth Franke class tube method with the little device he sells.  They are a bit low from the mark on the glass tube. But they are even.  I think they have been at this level all along.  I may try to raise them up.  I checked all the filters in the carb bodies, they look fine. I checked the tightness of the bolts they are all fine.  

I run about 12.3:1 at idle on my wideband. 

I will try to adjust the floats this coming friday when I have more time off. 

 

You know I had always wanted to see what some DCOE 45's would do on this engine...

 

[LeonV]

I don't see what else an over-pressure condition could have done. You're checking the float levels with the car running, correct? What is the actual measurement?

Double-check your sync, not that it's related to fuel pressure.

[Zedyone_kenobi]

NO I checked them with the fuel pump running but the engine off. Figured as long as their was pressure on the system it would be fine.

 

[zKars]

Man there isn't much that high input pressure do other than overwhelm the needle seat and overflow the bowls. Once the pressure is right, nothing else should be an issue. Maybe the needle fit changed, or the floats where tweeked? Might make a pretty high velocity jet through the needle orfice. Who knows what it caused. 

Do check float levels while running if that's possible. You need the in/out flow stabilized to see where the floats sit in operating mode. I'd be tempted to take a look at the floats and pivots and needle tips to make sure everything is tickatee boo.

[Zedyone_kenobi]

Well said and I will do exactly as stated. I will take measurements again while the car is running.  Would be a good time to clean everything off as well. I will probably weigh all the floats as well to see if any gas has some how worked its way into the pores affecting buoyancy.

 

 

[LeonV]

When you check the floats, take a caliper/depth gauge and measure the distance between the bottom (fuel-side) of the clear tube and the collar. If it's 24mm or less, you need to lower your float levels. I run 25mm on mine. 23mm is the height of the aux venturi passageway, as referenced from the float gauge.

[Zedyone_kenobi]

Interesting... I will check. I can tell you how far the level is from the outside top of the cover to fuel level. But not the inside top of the cover to the fuel level. I will take off a cover and measure the thickness of the plate so I can subtract the two.  Will be interesting. Just to be clear, you are saying with the fuel level at operating height, The distance from the top of the fuel level to the inside of the fuel bowl's ceiling should be 25mm.  Well that should be easy to determine.

[LeonV]

No, sorry. I'm talking about measuring the float level using Keith's tool. It's a clear tube made of polycarbonate with a sliding collar to mark the level. You said, "They are a bit low from the mark on the glass tube" and I want to quantify what you mean.

"I can tell you how far the level is from the outside top of the cover to fuel level." - That's the number I was curious about, mine are at 25mm measured from the jet block shelf (as I like to call it) down to the fuel level.

[Zedyone_kenobi]

Yup, this is the tool you are referring to. I love this thing.    This is when I first got it.  Currently,

 IF you take the white collar shown in this picture, and move it to the left passing the first indication until it is about 2-3 mm to the right of the second indication,  that is where my fuel levels are on my Z right now.  

[LeonV]

If that is the case, your fuel level is likely at (or over) the brim to the auxiliary venturi passageway. In other words, your float levels are likely too high. Are your air horns wet with fuel after running the engine?

Proper float adjustment is done as follows:

This is assuming you're using the right side of the rod to dip into the fuel, as pictured. Adjust the floats so that the RIGHT side of the sliding collar is flush or slightly to the left (1mm) of the RIGHT hash mark on the PC rod. That should measure 25mm using the depth gauge on a caliper.

Here's how I set my floats:

Write down your current float levels as measured with a caliper depth gauge, using the method as described above. Sounds like you're at 23mm. Remove the cover and put it upside-down on a workbench. Using a caliper, measure the distance between the float and the cover when the float tang just touches the needle valve, as shown in the 8.5 dimension in this photo:

DO NOT worry about the actual number but do write it down. We're only concerned with the difference. If your floats are too high, you need to increase this measurement by the amount that your floats are off, i.e. this is a 1:1 relationship.

For example, if your current float setting is 23mm as measured from the top and we want it to be 25mm, then increase the distance between your float and cover by 2mm. Visualize what this does and you'll understand. That means that if you measured 8.5mm currently, then that needs to be increased to 10.5mm. By setting floats this way, I can usually get them close, if not perfect, in one try.

DO NOT be concerned if all three carbs have slightly different measurements between the float and cover. We're only worried about the actual measurement from the jet stack shelf down to the fuel level (with the engine running).