leaking webers

[crazyoctopus]

noticed some dripping coming out of the front carb this morning...

 

I checked the float this morning by following this http://www.webernorthamerica.com/pdffiles/WeberFloatlevelinginstructions.pdf

I am curious though if i would be measuring to the seam of the float or the edge? after I made the adjustment it was still leaking on start up, but i did measure to the edge.

 

I am not running a return hose, but just bought some more hose so that I can if i need to. I am also using only the mechanical fuel pump.

 

any ideas?

[cygnusx1]

  The Weber manual says to measure to the floats body, not the seam.  There are very different settings for plastic vs brass floats (DCOE carbs came with both, and I don't see the DCOE Plastic float specs on that sheet). Also when you install the main jet assembly and idle jet assembly, leave the tips of the jets NOT fully pushed in.  Let the action of screwing in the jet assembly seat them.  The BEST method for float adjusting is to measure the fuel level in the main jet tubes with a dipstick or a vernier caliper.  I don't have the recommended levels handy but you can find them on the web.  With that amount of fuel coming out you have either really high fuel level, needle valves that are not seating, excessive fuel pressure, bad jet seats, or cracked bodies.  Return hose is not needed as long as the carbs see 4psi MAX 

 

For plastic DCOE floats the settings are 12.5mm closed and 25mm open from the center of the top float face to the carb cover gasket.  Again, double check the FULL fuel level with a dipstick from the fuel surface to the top of the emulsion tube well. Specs escape me right now.

 

Here is something I just found...can anyone confirm this number?  Fuel level should be 25mm from the top of the carb body, or 2mm below the auxiliary venturi spillway.

Edited April 18, 2010 by cygnusx1

[crazyoctopus]

i do have the brass floats and i'll recheck the distance again, and yes i use a set of digital V calipers.

 

I havent read anything before about how the jets seat, but i will re-do them just to make sure that they are seated correctly.

[crazyoctopus]

-Reset the jets just like you stated

 

-Checked the float level and made sure it was at 8.5mm when the tab was just touching the ball valve in the float. When I did a blow through test the needle valve was stopping the air coming out of it.

 

-While I was running my temp fuel pressure gauge the needle never went beyond 3.5psi; so doubt it is excessive fuel pressure.

I was curious to see if it leaked at every rpm, not just at idle. Once I did rev it up, the leak went away, only to return again after a short stay at idle.

Edited April 18, 2010 by crazyoctopus

[cygnusx1]

-Reset the jets just like you stated

 

-Checked the float level and made sure it was at 8.5mm when the tab was just touching the ball valve in the float. When I did a blow through test the needle valve was stopping the air coming out of it.

 

-While I was running my temp fuel pressure gauge the needle never went beyond 3.5psi; so doubt it is excessive fuel pressure.   

I was curious to see if it leaked at every rpm, not just at idle. Once I did rev it up, the leak went away, only to return again after a short stay at idle.

The leak will go away when you open the throttle plates because you have exposed the source of the fuel leak to engine vacuum, and it gets sucked into the cylinders instead of running out the stacks.  Are all of the carbs doing this?  Try to verify that the fuel level in the bowls is below the spillway for the aux venturies.  The only way for fuel to get out of the bowl is through the jets valves and ports...one of those is leaking unless the body has a crack in it.  

Edited April 19, 2010 by cygnusx1

[crazyoctopus]

it is only this one carb that is leaking fuel out of the front.

 

how do i verify that the fuel level is below the spillway?

 

also i tried to make the fuel bowl run a bit shallower than the rest by extending the resting point by about 1.5mm. From what I know of float bowls, by extending this distance the fuel level would be lower. At first this seemed to work, but then after a bit of time it didn't change anything at all, if anything it made it worse.

[cygnusx1]

it is only this one carb that is leaking fuel out of the front.

 

how do i verify that the fuel level is below the spillway?

 

also i tried to make the fuel bowl run a bit shallower than the rest by extending the resting point by about 1.5mm. From what I know of float bowls, by extending this distance the fuel level would be lower. At first this seemed to work, but then after a bit of time it didn't change anything at all, if anything it made it worse.

 

 

 

 

Here is an easy test.  Assuming all your DCOE's are the same model/vintage, measure the fuel level in the two good carbs by letting the bowls fill up.  Shut off the fuel pump, take out one main jet stack on each of the two good carbs, and stick a small stick, nail, or something to get a reading on the fuel level in those bowls.  Then do the same for the leaking one.  All floats are not the same, maybe, just maybe, the leaking one has a heavier set of floats for some reason.

 

You also can switch parts between carbs (floats and jets) to see if you can chase the problem.  You need to make sure that the floats don't bind anywhere and that the tab pushes on the needle valve ball pretty squarely, as viewed from the side.

 

 

 

[yetterben]

I bet this is the carb that does not match

[crazyoctopus]

actually it is one of the matching carbs that was giving me the issue lol.

 

As far as equality goes i'll double check tomorrow but i remember them all being 26 floats and 175 needle valves, but I have no way of knowing if the float has been modified.

 

 

I'll do the level check, and part swap tomorrow and see what happens

[cygnusx1]

Did you buy these carbs off of ebay a while back where one carb was different?  I remember a set like that for sale.  Looked like a nice set.  I bet it's a fuel level issue.  Probably a soldered float that weighs in overweight.

[crazyoctopus]

nah i found em off craigslist for $600 with mikuni mani, rubber mounts, linkage, and spacers; just missing the horns and a couple filters. although technically they only cost me 450 because i sold the SU cores.

 

I am hoping that all the problems are around fuel level, and that all i would have to do would be to swap in a new float

[cygnusx1]

 I was looking at the pics of the car at the blog.  Looks cool in olive drab...that's what I'm calling it...the tail muffler from MSA??  Dynaflow?  Can be rotated 180 degrees from where you have it so that the "lobe" of the muffler (in cam talk) fits up into the rear quarter.  That way you barely even see the muffler.  I didn't think it would fit but, I did it with mine, and it fits perfectly with the tailpipe dead center in the cutout. No rubbing!  I can get my hand all the way around the muffler in there!

 

 

Sort of like this:

 

 

Sorry for the thread jack and now back to your regularly scheduled Weber talk!

 

 

Edited April 19, 2010 by cygnusx1

[crazyoctopus]

thanks, and yeah olive drab is the best way to describe it, the can called it "ultra-flat deep forest green" which is a mouth full.

 

and yes those pictures are a bit outdated, the exhaust was rattling too much against the chassis so i had to remove it and spin it a bit, now it is just like yours is; super hidden. The one thing that i dont' like about the MSA's Dynaflow muffler that they sent was a fail-chrome tip.

[Konish]

  The Weber manual says to measure to the floats body, not the seam.  There are very different settings for plastic vs brass floats (DCOE carbs came with both, and I don't see the DCOE Plastic float specs on that sheet). Also when you install the main jet assembly and idle jet assembly, leave the tips of the jets NOT fully pushed in.  Let the action of screwing in the jet assembly seat them.  The BEST method for float adjusting is to measure the fuel level in the main jet tubes with a dipstick or a vernier caliper.  I don't have the recommended levels handy but you can find them on the web.  With that amount of fuel coming out you have either really high fuel level, needle valves that are not seating, excessive fuel pressure, bad jet seats, or cracked bodies.  Return hose is not needed as long as the carbs see 4psi MAX 

 

For plastic DCOE floats the settings are 12.5mm closed and 25mm open from the center of the top float face to the carb cover gasket.  Again, double check the FULL fuel level with a dipstick from the fuel surface to the top of the emulsion tube well. Specs escape me right now.

 

Here is something I just found...can anyone confirm this number?  Fuel level should be 25mm from the top of the carb body, or 2mm below the auxiliary venturi spillway.

 

Yes, I too have read in various places that 25mm from the top of the carb body is the optimal fuel level (which indeed does correspond to 2 mm below the main spillway).

 

I used a thick plastic drinking straw that just fit inside the main jet stack socket. I used another thick plastic straw to make a shim that fit around the measuring straw and sat directly on top of the body (larger diameter than the main jet holder). The shim has just enough friction to allow the inner straw to slide down the socket with controlled pressure. Slowly push down on the edge of the straw (so you can see down inside it's length) and at the moment the straw makes contact, you'll see the surface tension break. Withdraw straw and measure against the shim. Or you can buy the $40 clear plastic rod on Ebay and it'll do the same thing.

[crazyoctopus]

swapped the jets and nothing changed.

 

swapped over the float and the leak followed the floats.

 

so it looks like I need to nab myself a new set of floats!

[cygnusx1]

swapped the jets and nothing changed.

 

swapped over the float and the leak followed the floats.

 

so it looks like I need to nab myself a new set of floats!

 

Nice.  Cheap and easy fix.     BTW, still try to set your fuel levels by measuring the depth of it from the top of the carb body.  If you look down into the main jet port, you can see the spillway to the left.  Fuel should be 2mm below that hole.

Edited April 19, 2010 by cygnusx1