1st drive with the Webers

Rick Parker · #1 (**permalink**) 08-23-2007, 06:15 PM

After much tuning , inquiring, asking, fretting and applying I finally got the "tune" where I felt comfortable to take it out on the road with the IDA's. After reading about all the possible transition problems and considering the potential need for the "3rd Transition hole" I was relieved to find that as of now the car and carbs seem to flow seamlessly from 1500-4000 without ANY hickups or hesitancy. I only drove it for about 20 minute and went down to visit a friend who wanted to see the final install. Unfortunately the 2 piece upper radiator hose began to slide off of the metal tubing piece that forms the joint for the 2 pieces of hose and I was on the began to lose the coolant after I stopped. While we had it idling one of the floats appeared to stick and raw fuel began to get dumped so I shut it off. It continued to drip for a couple of minutes.
Have any of you had a float stick like this? What caused it? I have fuel filters inside each carb and in the line prior to the mechanical pump and 2.5# constant pressure. Looking for a answer for that (????)
No air filters............
Thanks

PatBuckley · #2 (**permalink**) 08-23-2007, 06:21 PM

Congratulations, Rick!

They are nice.

hohorodshop · #3 (**permalink**) 08-23-2007, 07:13 PM

Guys on the FFCobra page were having problems using the air filters on the Webers

427Aggie · #4 (**permalink**) 08-23-2007, 07:39 PM

IF you are running those cheap rubber filters....FORGET IT..they change the flow characteristics TOOO much and you can ever get the tune right because of the changes to the airflow

Now on the float sticking..are you sure it was the float? Where was the fuel coming from ? If it was coming from the pump jet do you have press in pumps or the screw in type?

I just noticed this is on a 289 so you probably don't have the problem with the pump jet not sealing correctly that is limited to 427's

Did you set the float's in these carbs when you got them? Don't assume they were set correctly from the factory!

Rick Parker · #5 (**permalink**) 08-23-2007, 07:57 PM

I had set the floats previously and have had it running for a total of about an hour and a half while arriving at what I felt was a correct set of jets and state of tune. Then today I drove it the 4-5 miles and it ran well. Just don't understand what might of caused it? It began after it was idling about 2 minutes after arrival.

Rick Parker · #6 (**permalink**) 08-23-2007, 08:51 PM

427Aggie
The fuel was being dicharged from the opening in the Auxilliary Venturi (main system). The accelerator pump jets are screw in type. The leaking needle valve had to be caused by either a stuck float (bottom of travel) or foreign matter in the needle valve itself. I'm thinking stuck float.

427Aggie · #7 (**permalink**) 08-24-2007, 05:40 AM

The old needles are bad about sticking or there is something else that could have happened.

Sometimes the floats will get holes in them and fill up with fuel..I would check to make sure that its not just getting heavy from filling up with fuel. I have had to change out the floats on mine before if all else failed and I couldn't figure out where all the gas was coming from..something to think about since these are brass and will sink

Rick Parker · #8 (**permalink**) 08-24-2007, 08:08 AM

The floats as well as the Needle & seats are new. (????)

Full Throttle Al · #9 (**permalink**) 08-24-2007, 08:56 AM

Rick,

You have a pressure regulator set to 2-3 psi before the carbs? If the problem is intermittent, it can't be the floats filling up with fuel since that would be constant. Assuming you are not getting too much fuel pressure to the needle and seat, it was probable some thing preventing the needle valve from closing (dirt, something that got in the system during install). I had the same problem once, removed and cleaned the needle and seat and it has never recurred.

The best way to get your final tune is using ex gas analysis either with a dyno or not. They make units for home use now, about $300. Any new sidepipes should be built with a bung for the sensor to make tuning easier.

Alan J Sorkey
Shreveort, LA
CSX4083 The Cammer Cobra with Webers

Snakebit · #10 (**permalink**) 08-24-2007, 01:00 PM

Rick, what did you end up with as far as jets and airs? Did you drill the third progression holes?

Rick Parker · #11 (**permalink**) 08-24-2007, 05:45 PM

Keep in mind this is a 289 OK. Pretty healthy cam but definately not "undrivable". I soldered the 1.20 Idle holders up and redrilled them to 1.0 (leaving room to go to 1.10 if needed) I am currently using 60 F10 for Idle jet. 1.55 mains and currently 2.00 air correctors. Accelerator pump squirters are .50 and the bypass in the bottom of the float bowl is .55. All this with F7 emulsion tubes. My experience while initially tuning was that the standard 1.20 Idle holder was causing it to be lean. Although I did not drive it until put the resized 1.0 Idle holders, I could immediately tell that it reacted differently upon starting. I will also say that I will try the recommended 1.10 sizing a little later (which will make it idle leaner) but right now there is no black exhaust while idling and the transition is seamless (for my application) without the 3rd progression hole.
I have not done any plug cuts yet. I have spent a lot of time and effort on this project and used information provided by several individuals who were kind enough to assist by sharing information (thank you all very much!) in helping me try to find a base line from which to start. I think I am ultimately real close, but still have some work to do. It is quite a journey.
I will be happy to assist any of you too.
Again thanks to each of you who shared info and made recommendations for my application. That's what this site is all about.

Tongue Pirate · #12 (**permalink**) 08-24-2007, 07:09 PM

Damn it Rick, Tell us how that ride was!

Tell us you couldn't feel the difference between 1 carb & 8 venturiis individually feeding hungry cylinders

You'll get her figured out soon enough, keep at it! Good luck!

Eljaro · #13 (**permalink**) 08-29-2007, 04:29 PM

Rick,
a dirty needle valve can cause that. The slightest rest of gasket, silicone or gas tank dirt can prevent the needle valve from closing.
But you should consider one more thing:
I used to have all four carbs pouring gasoline into the throats on idle and after shutdown. I could hear the gasoline boiling inside the bowls. So I installed a set of phenolic spacers, and made myself even a set of phenolic washers for under the screw heads and all was well again.
On top of that I took a a return line from the second output on my Holler fuel pressure regulator and fed it back to the fuel line before the mechanical fuel pump, with a 115 air corrector jet pressed inside the tee fitting to limit the flow of the feedback.
Now the pressure stays up and is more stable but as soon as I shut off the engine the fuel pressure is relieved through the bypass in a few seconds. No more residual pressure on the needle valves, no more gasoline pouring into the throats.