Are my float levels too high? - Carb flooding

[rollo1504]

Hey Guys!

As some of you might already have read in another topic I have rebuilt by Holley 4160 4BBL vac sec carb some time ago.

Since I have it installed back onto the intake manifold the motor runs quite good but I can see that there is quite much fuel in the valley pan which gives me not a really good feeling...

So my question is before I start unmounting too much things If the float levels of my carb are set too high....

I have to say that during the rebuild process I have adjusted the float levels as the holley manual for my carb told me to do so.... (put float bowls upside down and check if they are parallel aligned etc)

Or did I some other thing wrong...?

Thanks for any input.

Roland

[XH29N0G]

That does not seem right at all.  It also looks like a fire hazard. 

My guess is that the float level being too high would send fuel out the boosters and down into the carb barrels filling the manifold with fuel. 

I would look for a bad connection or a leaky gasket on the float bowls or the metering blocks or the accelerator pump.

[rollo1504]

YES, it IS a fire hazard, thats why I am questioning and afraid of continuing driving...... .

Mmmmhhh. I was working really slowly and doublechecked everything twice concerning the gaskets but I will check that again....

I also assume that the float level is too high.....

....

To be continued...

Thanks Roland

[XH29N0G]

I would also check the tube that connects the two fuel bowls.  Is the capped hose in the top right of the picture, a vacuum hose?

[sccachallenger]

look at the accelerator pump diaphragm housing while you work the throttle linkage.
A pinhole in the diaphragm will drip fuel every time the throttle is moved.
If the engine runs well, and is not hard to start when hot,(like it's flooded)the float level is probably OK.
As always, let us know what you find.

[rollo1504]

I would also check the tube that connects the two fuel bowls.  Is the capped hose in the top right of the picture, a vacuum hose?

Yes, this is a vacuum hose to my vacuum gauge....Everything fine there

[rollo1504]

..... mmmmhhh another thing I have to mention is that I also have replaced the powervalve....

Is there a possibility that this thing is broken and because of this it is permanently open and too much fuel floods in?

Just thinking....

Thanks Roland

[XH29N0G]

I think the power valve would just send gas into the boosters because there is still a gasket on the metering block to hold the gas in the bowls and keep it from leaking out. 

I would search around for leaks at all possible connections that lead to the outside.  With that much gas, it has to be coming out somewhere.  If it is not leaking out when the engine is running, then maybe it is something that happens with the fuel pump is working.  The suggestion by sccachallenger is a good one because it involves a test that is not a simple leak, but something that happens when the throttle is depressed.  I would check around with a paper towel to see if any leaks could be located, then try the same while manipulating the throttle, and then with the engine running.  My guess is that you will find a leak with the carburetor or with one of the connections to the carburetor or hoses.  don't forget the tube that connects the two bowls.

[rollo1504]

Ok.... Concerning the left red square in the pic.... It looks like that fuel is slighty coming out of the linkage which opens the secondaries ....

... and the other thing at the moment I am guessing around is HOW is fuel coming to the valley pan (seee right red square in pic)? Might this indicate also a leak between heads and intake manifold? Just asking as I think if the fuel would go down outside the carb over the intake into the valley pan there would be much more messed up with fuel on the intake as fuel must get over the intake to the valley pan...

Sorry for my bad english I hope you guys understand what I mean though...

Thanks Roland

[rollo1504]

I have also checked some pix in the internet of the underside from the intake manifold....

In my opinion all these breadcrumbs lead to the point that there is something wrong with the Throttle Body of the carb or its gasket....

We'll see

[XH29N0G]

If you think you have a spot where fuel appears to be coming out, I would focus there and on any joint or gasket near that point.  I suppose it could be near the throttle body, but maybe where something is connected with the floats.

No worries about the English.  (1) I am almost certain my responses would be impossible if I wrote in your language (which I assume I do not know) or even in other languages that I think I know how to speak. 

[rollo1504]

Update:

Fired engine up yesterday....

Cold Start: Engine cranked pretty good and ran almost instantly.... Let it runf for a while to get hot and checked carb outside if fuel drops out somewhere -> NO FUEL DROPS out
Hot Start: Engine fires up immediately

Then things started to get interesting

As I COMPLETELY screwed in both idle mixture screws the engine DID NOT DIE!

So I think following things are happening....

- Possibility A: The newly installed powervalve is defective and is permanently open which causes the engine not to die after closing the mixture screws
- Possibility B: The power valve blow protection has a small ball inside so far as I can remember... Mmmhhh. At the moment I do NOT know if I have checked it if the small ball is inside the blow protection or not
- Possibility C: As I also took both fuel bowls apart I might have done something wrong during reassembling it but to be honest I do not really believe that....
- Possibility D: As I can see much fuel in the valley pan after driving around for a short while and have pushed it several times I also think that the secondaries are opening way too far so the engine does not burn all incoming fuel which leads to this fuel leak in the valley pan....

Sounds like I have a plan or at least I found some possibilities to check....

By the way I do not think that it is a gasket issue....

Thoughts?

To be continued....

Thanks Roland

[XH29N0G]

I don't have further thoughts, hopefully someone else does.  I will let you know if I get any ideas.

[charger Downunder]

You may need to replace the needle and seat it may be damaged at the end and leaking fuel in when it should be closed.

[rollo1504]

You may need to replace the needle and seat it may be damaged at the end and leaking fuel in when it should be closed.

During rebuild process the needles have been replaced....

But I will come back as soon as I have an update about the situation as I still have not checked it yet...

Thank you all for your thoughts and help

Roland

[rollo1504]

Update:

- Possibility A: The newly installed powervalve is defective and is permanently open which causes the engine not to die after closing the mixture screws
- Possibility B: The power valve blow protection has a small ball inside so far as I can remember... Mmmhhh. At the moment I do NOT know if I have checked it if the small ball is inside the blow protection or not
- Possibility C: As I also took both fuel bowls apart I might have done something wrong during reassembling it but to be honest I do not really believe that....
- Possibility D: As I can see much fuel in the valley pan after driving around for a short while and have pushed it several times I also think that the secondaries are opening way too far so the engine does not burn all incoming fuel which leads to this fuel leak in the valley pan....

Did not have time to take the carb apart but can say that there was a fuel leak in the valley pan because there was toooooo much fuel incoming from the carb which could not be burned by the motor. As I said the mixture screws are completely screwed in I wanted to know how car behaves when I try to make a short drive.....

Car ran almost fine and after the return there were NO fuel lakes anymore around the intake manifold and in the valley pan....

So I suppose that the new power valve is broken and is permanently open and additionally with the mixture screws set to 1,5 turnarounds loosen the motor was running far way too rich....

As engine fires up immediately even if HOT then the fuel levels in the float bowls should be fine...

So the only logical conclusion is the powervalve..... But that are my thoughts and I am NOT a mechanic.....



Will be back soon.

Roland

[XH29N0G]

I am glad that the leak has worked itself out. 

I believe if the power valve is ruptured then you might leak fuel into the other circuits, but if it is not ruptured, I think it should feed fuel to the same place the main Jets do (the boosters) and this should not affect idle.

Check the transfer slots to make sure they are not set improperly.  This can also determine whether the idle mixture screws work.

[68 RT]

If your screw in your mixture screws all the way and the car does not stall one thing to check is your idle speed screw, it is probably in to far causing the throttle blades to be open too far.

[sccachallenger]

If your screw in your mixture screws all the way and the car does not stall one thing to check is your idle speed screw, it is probably in to far causing the throttle blades to be open too far.

Agreed! open the secondaries a little(takes a tiny screwdriver)this should let you close the primary side a little and may restore the idle screw function.
It may take a couple of tries to get this right, but worth it!

[rollo1504]

I have set up the secondaries like many guys told it in the web to the famous "Square" by adjusting the small screw underneath the throttle body plate.....

Mmmmmh... was this wrong...

OK OK I think I understand now more whats going on and HOW a carb is working or its parts....

Last time I played around with the curb idle screw I could see that I was not able to stall the motor with it even if completely loosen.... -> I guess then that my throttle blades are open to far in the "ZERO" position? right?

Thanks

[sccachallenger]

you may be at the other extreme!
Hold the carb over a strong light.
it'll give you an idea how open the throttle plates are.
if you see more that a small crescent of light from around the secondary plates they may be open too far.
Make a very slight adjustment to close them slightly.
This assumes that the stop is against the screw when throttle is closed, If not you may have to adjust(bend) the closing link to allow them to close fully.
Make sure the closing link isn't holding the secondaries open,even slightly.

[XH29N0G]

The transition slot with a Holley carburetor flipped upside down should be a square shape.  If it is this shape, then it works as designed.  There are also transition slots on the primaries.

It is probably also significant that your car does not die with the idle speed screw completely backed off so that the primaries are closed.  What is the idle speed (RPM) when the idle speed screw is backed out.  Also make sure the throttle cable or something else isn't holding it open a little. 

[rollo1504]

... Today it was the time to take the carb apart again....

Could find 2 things:

- Power Valve was installed with 2 gaskets... Do not know how I could have overseen that.....
- Secondaries were open to far (Did the test with the bright light idea) :-)

In the next couple of days I will have the time to put all back together and check the RPM if curb idle screw is completely loose...

More to come...

Thank you all for your suggestions/ideas

Roland

[XH29N0G]

While you have it apart, it is worth making sure all passage ways are clear.

I found it informative to track down the passageways with information like that at the bottom of this web page: http://members.tccoa.com/392bird/tuning.htm

I hope to hear about a successful fix soon

[rollo1504]

Hello Guys!

Well I think I have good news....

After replacing the "new" power valve with another new power valve and install it with one instead of two gaskets :-) the engine dies if idle mixture screw are screwed in...
Further the secondaries were open too far... Adjusted them with the bright light hint. Now the car dies if the curb idle screw is screwed out to far as well.....

There are no vakuum or fuel leaks caused by a worn out/damaged gasket or something like that....

So engine runs pretty good in idle and responds very fast if pushed (as far as I would understand it)....
Replaced also the vacuum diaphragm of the secondaries and tested it if they open with a paperclip... yes, this seems also to work....

the very last problem I have is now that I think the engine leans out if WOT for some seconds and engine stumbles then just a little bit....
What do you think guys I can do to fix this? Currently a 6.5 power valve is installed..... Could it have something to do with the secondaries opening too early or too late? Or will I have to look for bigger jets?
Have to mention that my carb actually only has primary jets and NO secondary jets.

Thanks

Roland

PS: During some more testings I figures out that the intake manifold is just a little bit leaky at the heatcrossover to the cylinderheads. Have bought this famous Black RTV Silicone tube to fix this....