Holley Float Problem

[sixty9vette]

Fiddling with a used Street Avenger 670. Can't get the secondary float level adjusted. Primary bowl adjustment works fine, but secondary stays way too high (above sight glass). There's no trash on the N&S and tried swapping the primary and seconday N&S to make sure that wasn't the culprit. Also tried another new N&S just to confirm. Float is is good shape, but also tried one off another Holley to make sure that wasn't the culprit. Then I tried a new one. Same thing. Fuel pressure is approx 7psi. My other Holley (4777) works fine at that psi. The metering block is pretty basic, with just provisions for jets. Where to from here? :confused

 

[72Mako]

Chris, explain how you are setting the fuel level on the secondaries. Do you dry set the float level before assembly? Does the gas start pouring out when you pull the sight plug and continue to pour out even as you are adjusting the N&S to raise the float? Charles

 

[sixty9vette]

Charles... I set front & back dry to begin with, using a #2 pencil width as a gauge. The carb has the sight glass, so no need to remove a plug. With that initial basic adjustment, the front level was slightly high at about 1/4 up the glass, and the back level was not visible, but above the the sight glass. I adjusted the front N&S and got the level just a tad below the sight glass, which would be equivalent to a trickle if you had plugs. I tried the same on the back. Nothing. I checked for trash, and even swapped the N&S with the front (as well as another new one) and no change. New float & no change. Measured floats and pivot arm and angle - same. The rear float had been replaced before I got the carb, so perhaps somebody else had this problem and tried a different float. Hmmmm...

Chris, explain how you are setting the fuel level on the secondaries. Do you dry set the float level before assembly? Does the gas start pouring out when you pull the sight plug and continue to pour out even as you are adjusting the N&S to raise the float? Charles

 

[72Mako]

Chris, I'm far from a carb expert, but when adjusting the float level on the primary side of the carb, there is a constant draw of fuel because the idle circuit is fed from the primary bowl as the engine is running. So the fuel level responds to you adjusting the N&S assembly. On the secondary end, there is no draw from the secondary fuel bowl until the secondaries are activated-ie when you floor it. That is why I was asking about how you were adjusting the secondary N&S assembly. Charles

 

[72Mako]

Chris, I'm far from a carb expert, but when adjusting the float level on the primary side of the carb, there is a constant draw of fuel because the idle circuit is fed from the primary bowl as the engine is running. So the fuel level responds to you adjusting the N&S assembly. On the secondary end, there is no draw from the secondary fuel bowl until the secondaries are activated-ie when you floor it. That is why I was asking about how you were adjusting the secondary N&S assembly. Charles

Scratch that Chris. There is a flow from the secondary bowl as well at idle. So were back to square one.

 

[vette-dude]

The last time this happened to me the o-ring on the float had a nick/cut in it and I could not reset the float level. Also make sure the needle housing is engaging the threads in the float bowl. You can check this by setting up the float dry before installing. Use a little oil on the o-ring when installing. I realize you mentioned you use another needle and seat assy but check the o-rings as they get hard and brittle and split when you install it in the bowl. Good luck.

Randy

 

[sixty9vette]

Thanks for the info. The N&S is new and the o-ring is ok (tried a couple of them). I did set the floats dry and they didn't have a problem moving up and down during that adjustment. I also added a thin coat of white lithium to the o-ring. The float isn't binding when the bowl is filled. I checked and rechecked the bowls, measured everything (mic) and it checks out ok. Also inspected the bore for the o-ring seal and no defects that I could see. I'm stumped... :cry

 

[GerryLP]

Chris,

Any new developments on this issue?

 

[vette-dude]

I wonder if the power valve is blown? I had this problem once and I can't remember if that was the problem or not. One back fire of the carb takes out the valve unless you have a check valve installed in the carb. The only other thing I can think of is the threads in the float bowl are stripped and when you crank down on the hex nut it pulls the N&S out of the threads raising the floats.


Randy

 

[GerryLP]

I wonder if the power valve is blown? I had this problem once and I can't remember if that was the problem or not. One back fire of the carb takes out the valve unless you have a check valve installed in the carb. The only other thing I can think of is the threads in the float bowl are stripped and when you crank down on the hex nut it pulls the N&S out of the threads raising the floats.


Randy

Randy,

The power valve when blown will make the carb run rich all the time, and didn't read that situation on your posting. There is a spring for the float that's suppose to assist in the float setting...but now we're reaching out far off the tree branch...:L

 

[sixty9vette]

Here's a reply from Holley tech support:

"Alot of people have this problem because they do not know that it does not use fuel out of the sec. end @ idle. You need to turn the nut 1/4 turn clockwise then drive it and open up the sec. and come back and check it again, if it it is still too high do it again (if it was too much PSI it would be on the pri. too).
Thanks Ricky"


Uh.. 1/4 turn from where? :eyerole
Not very detailed info, but i'll give that a try. I've been hesitant to drive it with fuel nearly coming out of the vent tube! I'll report back when I try this. Ok, where's my fire extinguisher... I did happen to inspect the bowl again around the area where the N&S o-ring would seat. With a black light, and from the bottom side you can see an obvious swirl, sort of like a cut that leaves a ridge that you can feel with a dental pick....

Chris,

Any new developments on this issue?

 

[GerryLP]

That makes sense, Chris. I didn't think that the pressure was a problem.

However, I recall that when I had the Avenger 770 in my car, I could reach the linkage below the diaphragm and force the secondary throttle plates open. On Sec Vac's carbs, the pressure drop across the primary is connected to the seconday through a channel. The spring on the other side of the diaphragm is there to "time" the opening of the secondary plates appropriately. The pressure drop overcomes the spring and then the plates open, so the linkage below should allow you to do this. The reason for driving the vehicle around could be that the "load" of the vehicle will help open the secondaries sooner -as oposed to just reving the engine to force the sec' to open [with load they will open sooner meaning lower RPM and with reving they will open at higher RPM].

On my dbl pumper, I just operate the secondary plates manually without operating the primary side. This helps reset the level. At any rate, looks like you will be able to correct the problem. I Hope it all goes well. Good luck!

 

[72Mako]

Chris, in my earlier reply, that was what I was thinking, that no fuel was being drawn from the secondary bowl at idle. But later when reading some literature on Holleys, it was stated that some fuel is always being used from the secondary bowl at idle. The literature was suggesting that if this didn't occur, that on a vehicle when the secondaries were never engaged (for sake of argument), that the fuel would become stagnant. The literature was saying that in order to keep the fuel fresh in the secondary bowl, a small amount is always being replenished. But Ricky at Holley is suggesting elsewise. Now I'm confused.:confused

 

[sixty9vette]

I've seen the same writeup you mention, which is why I was also surprised at their response. I wrote them back for a 'second opinion'. If this turns out to be right, their instructions ought to read... "when you first start the motor you'll notice the secondary float bowl is not adjustable and contains too much fuel. You need to drive the car at high enough speed to open the secondary side and allow this excess fuel to flow. Stop the car and check your fuel level and make necessary adjustments. Keep doing this until the correct level is achieved. Warning: Carry a fire extinguisher, cell phone and AAA card. Braking your vehicle hard with a full fuel bowl will cause your vehicle to stall by shooting a large volume of gas out of the vent tube and into your motor, creating several problems. Washed cylinder walls contributes to early engine failure and is not covered under the Holley warranty. Fuel may run down your air filter base and make its way onto your intake manifold. We would recommend exiting the vehicle at this time. Should a fire NOT occur, return to the recommended adjustment procedures. Now you'll see why we call our Street Avenger a true bolt-on and go installation."

Chris, in my earlier reply, that was what I was thinking, that no fuel was being drawn from the secondary bowl at idle. But later when reading some literature on Holleys, it was stated that some fuel is always being used from the secondary bowl at idle. The literature was suggesting that if this didn't occur, that on a vehicle when the secondaries were never engaged (for sake of argument), that the fuel would become stagnant. The literature was saying that in order to keep the fuel fresh in the secondary bowl, a small amount is always being replenished. But Ricky at Holley is suggesting elsewise. Now I'm confused.:confused

 

[72Mako]

I've seen the same writeup you mention, which is why I was also surprised at their response. I wrote them back for a 'second opinion'. If this turns out to be right, their instructions ought to read... "when you first start the motor you'll notice the secondary float bowl is not adjustable and contains too much fuel. You need to drive the car at high enough speed to open the secondary side and allow this excess fuel to flow. Stop the car and check your fuel level and make necessary adjustments. Keep doing this until the correct level is achieved. Warning: Carry a fire extinguisher, cell phone and AAA card. Braking your vehicle hard with a full fuel bowl will cause your vehicle to stall by shooting a large volume of gas out of the vent tube and into your motor, creating several problems. Washed cylinder walls contributes to early engine failure and is not covered under the Holley warranty. Fuel may run down your air filter base and make its way onto your intake manifold. We would recommend exiting the vehicle at this time. Should a fire NOT occur, return to the recommended adjustment procedures. Now you'll see why we call our Street Avenger a true bolt-on and go installation."

Chris, Holley needs to hire you as their tech writer.I am running a Holley 4777 DP like you used to. When the carb was new, I had some issues (mainly quality control) with it and I noticed that their tech help was hit and miss depending on who you got when you called. I ran those clear sight glasses (don't remember if they were Holley or aftermarket) but noticed that after some time, they softened up from the fuel. I only run them briefly to check the levels and then replace them with the brass ones. The 4777 DP runs strong and has good throttle response but it sucks at gas milage . I guess thats why you're going to the vac secondary carb? Keep us updated. Charles

 

[sixty9vette]

:eyerole

After asking for some confirmation from Holley about having to drive the car and open up the secondaries to make the float adjustment, here's the response I received:

"If you do not want to do it this way you can remove a bottom fuel bowl screw and let some fuel out and then turn the nut clockwise 1/4 trun and check it again. do this untill you get it right. if you do not buy this there is no need to e-mail back. I am the tech for Avengers. thanks Ricky"

Guess Ricky got his feelings hurt by questioning his methods... What a maroon. :L Anybody out there with a Street Avenger that has had to adjust floats this way?

 

[1979toy]

Since I didn't expect to have much movement in the secondary side of my Street Avenger during my break in of my newly rebuilt engine I set the secondary float lower than the inital setting recommended. As I came back from a tuning trip I would check the sight plug. If there was no fuel there I would raise the level of the float a bit.

 

[sixty9vette]

I put the carb back on and took it out for a drive with a full bowl. Opened the secondaries but they just kept wanting to open on their own...oh wait... that's my foot..

Checked the float. Still high, so started the adjustment. I'm down to nearly no threads left, but it's now at the bottom of the sight glass, so I'm happy.

That li'l old vacuum secondary carb sure seems to be pretty responsive. The choke works great. Just had to adjust the fast idle down a bit. What surpised me most is that before I got the float level down, the engine didn't flood with sharp turns or hard braking. Man, that DP I have is very sensitive to that, even with a vent shield.