carbs are leaking bad :/

[slowbro]

i replaced the cracked intake on my 260z and now the carbs are leaking alot from the front where the suck air.

i have no idea what the prob is any suggestions?

 

i didnt flip the carbs, i kept em standing upright the entire time they were off. and the floats look good.

[ggzilla]

Does your car have an aftermarket electric fuel pump? Some are vacuum-controlled so may change pressure once you fix the manifold.

 

Another possibility is that one of the vacuum hoses was connected to the wrong spot on the intake manifold.

[slowbro]

it does have an electric fuel pump, but ill have to check what type and ima look through my book to recheck all the hookups.

[72240z]

Sounds like your flooding, def re check everything including the floats and needle valves

[slowbro]

yeh flooding is what i was thinking. floats and needles are good. and i stoped the leaking. but now it run really rough and now smokes black, which is usually means its rich right? motor didn't smoke before at all.

[72240z]

Ya black is usually rich. What carbs are you running the flat tops? what stopped the flooding?

[datzenmike]

Check that the fuel return line is properly connected. This dumps unused fuel back in the tank. May drop the fuel pressure slightly and definitely drops the pressure to zero when the motor is shut off.

[ggzilla]

Set the float level.

[slowbro]

not sure on what type they are there definatley stock though. ill have to check the return lines, not sure on how to set float level so ill have some reading to do

[ggzilla]

260Z stock carburetors are Hitachi 46mm units (HBM46W series). The infamous Z-car "flat-tops".

 

Setting float level is the foundation of a carburetor. It will run rich and/or overflow if the level is too high -- and all the tuning/adjusting won't fix it. Float level is the first thing that needs to be done.

[datzenmike]

Can't see how the floats have been affected form a simple manifold change. If it was fine before what has changed? Could dirt in the lines have flushed into the needle and is holding it open?

[72240z]

Thats really the point, there arent many things that can cause that issue. I asked what stopped it and never got an answer. Flooding then running black smoke rich even after it stopped sounds like the floats are too high or a needle valve/s are sticking open. Even if the pressure was too high or the return was non existent a properly working float and valve should keep everything working fine. A 3rd option is the chokes hanging up. Check to make sure they are fully returning when not engaged.

 

Read up on how to check and adjust your floats and needle valves. Everything is in the FSM which can be downloaded for free if you search.

[Sealik]

http://www.zcarz.us/TechnicalInformationPageCarburation.htm

[ggzilla]

So let's say the intak manifold was cracked every so slightly. So a previous owner richened up the carburetor to compensate. It still didn't run exacty right. Now new owner replaces manifold and engine is suddenly too rich.

 

Is one possibility

[slowbro]

yeh when i seen what actually caused the leaking it was a major face palm moment. haha i had the fuel line hooked up to the vent on the float chamber. i was so egar to fix it i didn't see it staring at me haha

 

but now i have to fix the rich problem and the roughness, thanks for the link looks like lots of good info. hopefully i can gete this done saturday.