It's always something

[Texasdoc]

Today I was driving down the road and punched it for about three seconds (had to pass the teenager in the v6 Camaro who wouldn't let me in the next lane). It pulled hard until I let off. A few seconds later it was running rough. A glance at the WBO2 showed it was at 10:1.

I pulled over and then it died. At first I thought my fuel pump died - it did this to me once before. The secondaries had fuel but I couldn't see a meniscus thru the primaries' sight window - but I could hear the pump running. After a bit I looked down the throat of the carb and there was fuel puddled on the throttle blades! It was dropping out of the boosters even with the motor off!

I opened the throttles (with the resultant hiss as the fuel hit the hot manifold - I had the extinguisher ready) and was able to start the car with the throttles at WOT to clear the flooded condition. It immediately flooded again and died and fuel puddled back up on the throttle blades.

I was able to get home by turning off the fuel pump with the dash kill switch and driving at low speed until the car started to miss as the bowls emptied, then flipping the pump back on for three seconds to filll the bowls, then killing the pump again.

About 20 minutes later, with the car finally back in the garage, I took out the needle and seat. I didn't see any garbage so maybe the float got stuck. I didn't have time to take off the bowl - I may get to that tomorrow.

It's always something...

[Gaz64]

Sounds like a jamming needle and seat.
Float dropped under heavy acceleration, needle jammed open and wouldn't reseat as the bowl overflowed.

What size needle and seats, and what fuel pressure do you run?

Gary

[pormgb]

I had a similar problem that drove me nuts for months, I would run the car then suddenly it would bog down and stall. The car would also start and run fine then run really rough, when I looked down the secondaries, I could see fuel pouring out of secondary squirters.

My car has a Holley 1850 with non-adjustable floats so I removed the secondary bowl and inspected and cleaned the needle valve and housing, everything looked good so I reassembled the carburetor. Many times, I thought I fixed the problem but it would always come back. I eventually bought a new $13.00 secondary valve and housing, this fixed the problem.

[Texasdoc]

5 # of pressure.
Needle and seat are 110.

Again, the needle and seat looked fine. I took it out, cleaned it with carb cleaner, re-greased the o-ring and put it right back. I didn't get the fuel bowl off yet - hopefully tomorrow.

Most of my quick review of the inter-webs state that a stuck needle/seat would cause fuel to come up out of the vent tube. Mine was obviously dripping from the Venturi booster. Any thoughts - does it matter?

I haven't done anything to the fuel lines in months. I have a 100 micron pre-pump filter, in-tank electric pump, and a 40 micron post-pump filter. A small amount of rubber hose going to the pressure regulator, then about 12 inches of rubber hose from the regulator to the carb inlet. Perhaps some of the rubber fuel line is degrading. I've been on Harris Hill Raceway for a full day and put on about 500 miles since I last did anything to the fuel line. I always use Lucas brand Ethanol fuel stabilizer.

I know they aren't great, but I may temporarily add one of those clear fuel filters between the pressure regulator and the carb for a while to see if it picks up any debris. I can't imagine the Holley HP billet ($$$$) filter is letting that much garbage thru to clog the needle and seat.

... I did have to clean the metering blocks in the parking lot with carb cleaner and compressed air... but that was late March. When I got back home I took the bowls off and cleaned the metering blocks extensively with cleaner and compressed air after removing all the IFRs, emulsion jets, Air Bleeds, etc. But I didn't do anything to the float, needle/seat, or bowl then.

[jhv48]

Check your fuel pressure.

[Texasdoc]

5 pound of pressure at the carb. I had driven it about 10 miles before this occurred. Something about hitting the throttle (only went about half-throttle for about 3 seconds) caused the issue.

[pormgb]

Replace the needle valve and seat, I tried cleaning mine many times and only when I bought a new set the problem got resolved. Even when I compared new and old, I could not see any difference.

[Gaz64]

Fuel comes out of the boosters before it come out of the bowl vent.

If it ever floods enough to come out of the bowl vent, it will certainly be pouring out of the boosters.

I would look at any rubber hose after your filters, pre carburettor, since line degradation failure ends up causing this.

Also look at the float tang that operates the needle and seat and the needle tip for any burrs that will jam the needle sideways and not allow normal up travel.

I am converting a few of my carbs to floatless, external adjustable fuel height, baffled (sloshless), runs as a return system.

Similar principle to others around, without the hiccups, or the extreme cost.

Gary

[moar_carbz]

I know this is a little late, but check your "float drop." On some floats there's a tab to adjust how far down the floats can drop when you're at high speed. If a float drops too far down, the needle can become cocked in such a way that the float can't easily push it closed again, then you have a flooding problem, which results in gas coming out the boosters. If you pull the float bowl all the way off you can look at the motion of how it opens and closes and see if this could be going on. The floats aren't really supposed to be able to touch the bottom of the float bowl if everything is right because this is what can happen.

[Riverside racer]

I experienced the same and fortunately had the air filter off with motor running (idling) in the garage and suddenly same symptoms occurred and I could see the fuel boiling and being dumped in the carb...Fix? Use a fuel with no ethanol and spacer and heatshield below the carb. making sure fuel line insulated. The Better fix is a regulator with a bypass and a return line to the cool fuel in the tank. Shell and Sunoco.
Ross

[FWB]

power valve bad or bad power valve gasket, maybe, did you look at it?

[Texasdoc]

Relatively new power valve, gasket is fine.

I have a 1" phenolic spacer, insulated fuel line, and bypass regulator.

It hadn't happened since that one day.

Hydraulic TOB started leaking.

It's always something....

[FWB]

i notice on mine, in the texas heat, my accelerator pump clearance on the rod, gets less,
sometimes non-existent, putting ever so slight pressure on the accel pump lever,
makes fuel dribble out of the boosters

[Gaz64]

Originally Posted by FWB

i notice on mine, in the texas heat, my accelerator pump clearance on the rod, gets less,
sometimes non-existent, putting ever so slight pressure on the accel pump lever,
makes fuel dribble out of the boosters

Clearance?

[patrickt]

I have always run a slight preload on my pump cam. Always, for decades. It's the only way to properly do it, IMO. And the only time I've ever had gas drip from the boosters it was a result of the floats being too high, or it being really hot and I had winter gas in there so it perc'ed out. Usually it's a combination of 1) float height; 2) underhood temps; and 3) gas quality.

[FWB]

i run about .010 feeler for a gap, you can't imagine what 102 or 105 degree weather does to your car unless you have experienced it.
Patrick honestly i see your car more in the hermetically sealed bag in your garage in your posts than out and about so you may be fine with the preload

[patrickt]

... ok, and you know that pressure on your accelerator pump cam can't make gas drip out of your boosters anyway.

[Gaz64]

A small amount of preload on the accelerator pump lever, adjusted for slack then remove the slack plus 1/4 turn, makes the accelerator pump function as it is designed.

So many guys run this .010-.015 at idle, which is completely wrong.

Any amount of slack gives a flat spot on initial throttle application off idle.

Any adjustment to the accelerator pump linkage will not have fuel discharging from the booster venturis, period.

If you have fuel discharging from the pump nozzle, then you need to check the pump cavity vent orifice for blockage.

Gary

[patrickt]

Originally Posted by Gaz64

A small amount of preload on the accelerator pump lever, adjusted for slack then remove the slack plus 1/4 turn, makes the accelerator pump function as it is designed.

So many guys run this .010-.015 at idle, which is completely wrong.

Any amount of slack gives a flat spot on initial throttle application off idle.

Any adjustment to the accelerator pump linkage will not have fuel discharging from the booster venturis, period.

If you have fuel discharging from the pump nozzle, then you need to check the pump cavity vent orifice for blockage.

Gary

Hmmm, Gaz speakum truthum.

[FWB]

well the pieces of doo doo i have, have tons of issues i'm sure, tired of rebuilding them
really looking at putting FI on mine,
FI Tech has a neat dual throttle body setup that bolts on to the 2 x 4 manifold.

i don't get what you mean by the accel pump won't make fuel come out of the boosters
maybe there's a disconnect in my explanation, press on gas, accel pump squirts fuel
right, so arm pressing on diaphragm......squirts fuel......


right from holleys instructions, i'm sure all of you know much better than holley

11.
The accelerator pump should be adjusted so that the slightest movement of the throttle lever results in actuation of the
accelerator pump. The pump override spring adjustment is checked while holding the throttle in the open position and the pump operating
lever held in a fully compressed position. The clearance
between the adjusting nut and the arm of the pump lever should be .015”.



and a note for "experts"


NOTE:
Under no circumstances should the pump override spring be adjusted to permit coil bind (or bottoming). This is
sometimes recommended by some “experts” as a means to a quicker delivery rate and increased flow. A
ll that such “adjustments” accomplish is to provide bent accelerator pump actuating levers and ruptured pump diaphragms.
Override springs are carefully sized to provide proper delivery pressure without damaging vital carburetor parts by
momentarily absorbing pump force and regulating the pressure peaks within the system