crw41

Last year, I ran into a situation whereby my Holley dumped gas on the engine during a cold start. I believe the float stuck. After some carb cleaner, it never happened again. Over the winter the carb was taken off, inspected, and everything looked good on it.

This year no problems. On the weekend I had the car out for 100 mile drive and it ran great. During the week, I had to pull the car in and out of the gararge a few times (alot of quick satrts and stops).

Today, it didn't start right away. I pumped the gas pedal a few times (too many) and it started after 3 cranks, but it sputtered. It would run at high rpm, but hesitated and felt like it was going to stall. I ran it around the block and upon coming back home, while at idle, it was running in a near-stall mode.

I turned the car off. I looked into the carb bowls (RED) and saw they were 1/2 full of gas, there was no spill over. There was alittle bit of black build up (GREEN) on the part shown. The gas was gradually draining its way down and from the carb into the engine.

A few questions:

1. I assume I flooded it during the cold start:

- What's the best technique to start a cold carbuerated car to
avoid this?
- When it does flood, how long should you let it sit before trying
to start it again?

2. I plan on letting it sit, cool down, using some carb cleaner and
then restarting the car. Other than a fire extinguisher, any
precautions?

This is the only thing that scare's me about this car - the thought of the Holley spilling gas onto a hot manifold and creating a bonfire! Too much time, money, and effort to this point to see it all go up in smoke.

w1ctc

I don't use the choke since I don't go out in cold weather often. For starting I turn the engine over until the oil pressure is up and then pump the gas a few times till it fires and keep it going with light pedal.

BarryK

whether it's been sitting a day, a week, or all winter I usually just have to pump the gas 2 or 3 times, turn the key and she fires up immediately!
Cold starts have never been a problem at all on my car. hot starts is more an issue where it may crank for a 5-10 seconds before she catches and fires but on cold starts she fires instantly pretty much every single time.

Johns_65Vette

I give a half pump on mine, and it fires right up. My choke is hooked up and set.

Cobra66

If the car has been run within the past week, I give two or three complete depressions of the accelerator pedal, then turn the key. Usually starts with very little cranking.

If more than a week since exercised, I do the same, but often have to give it a couple of pedal depressions while cranking.

So far (I'm knocking on wood--seriously!), it's started every time. I know my day will come, but the above regimen seems to work for my particular Holley setup.

Jack60

Same here.

SWCDuke

IF you have an OE carb in proper working order and adjusted to OE spec you should floor the throttle and then let up prior to cranking. A "cold start" is when the engine is at ambient temperature, whatever that is.

This procedure will inject fuel from the accelerator pump and set the choke and fast idle cam. In very cold weather two pumps might be better, then wait 15-30 seconds to let that fuel evaporate in the manifold. In very hot weather just depressing the throttle halfway rather than all the way will inject less fuel from the accel. pump, but still set the choke and fast idle cam.

"Flooding" in most cases occurs on hot restarts. In this case depress the throttle to the floor and hold it there. Then crank the engine until it starts. This is called "unloading". If the choke valve is set, flooring the throttle will open it enough that there will be no depression in the carb to pull in fuel. If the engine is hot the choke valve should be open, anyway. With the throttle full open and the choke open the engine will just "pump air", and once enough excess fuel is purged to yield an ignitible A/F ratio, the engine should start.

Duke

Cobra66

Excellent explanation, Duke. I "kind of" knew the rationale for why the difference between accelerator pedal depressions for cold vs. hot engine starts, but your description of exactly what causes what is enlightening.

Glad you're back!!

crw41

Thanks for the explanation.

Just curious:

1. In flooding - is it just a case of too much gas in the carb bowls at one time, not allowing air to get in thus, the engine sputters?

2. Holleys tend to flood more than other carbs?

3. Is it mostly a driver/technique issue, a carb issue, or both?

rgs

In reverse order,
In addition to, and as primary, have a wet towel handy for extinguishing carb fires. Works on most situations and eliminates the damage/cleanup from the extinguisher. Take the air cleaner off to protect it before starting to work on it.

Where are you using carb cleaner? If it is to loosen a stickey float as you said, did you remove the bowls to get to the float?

Duke's description was excellent for cold starting.

Your pictures and descriptions concern me. You said that you turned off the engine and looked in the carb bowls and they were half full, but you circled the venturis of the carburetor. If these were half full of gas, there is a serious problem. Can you check you picture and expound on this? You would have to take the sight plugs out of the bowls to check the level in them. Did you see liquid fuel sitting as a pool in the venturis?

The black buildup where you noted is indicitave of backfire through the carb. This can be caused by a number of things including flooding.

Take another look at your picture, circles, and verify your information. Especially about fuel in both the primary and secondary venturis. The carb shown has no secondary accellerator pump so ther are only a couple things that would cause your problem, most likely the secondary needle sticking resulting in fuel spilling out the vent and down through the secondary venturis.

ghostrider20

Holley carb here as well -

Cold start, as per owners manual, and what I do, and it works perfect.

Floor the pedal once, then crank. Mine fires right up.

Hot start, I just turn the key, do not touch the gas. Fires as soon as the motor turns.

Check your float bowl settings. I set mine so that the fuel is just below the sight hole, and when you rock the fender with your leg, it should just barely slosh out the hole.

Also check to make sure the choke cam, and linkage is free to move. They can get crudy.

Mark

SWCDuke

The same cold start, hot start, and unloading procedure is in your owner's manual without all the whys and wherefores that I added.

My dad explained all this to me when I was ten.

Duke

crw41

Excuse my ignorance, I don't know alot about carbs. This picture is for explanation puposes.

Where are you using carb cleaner? I lightlly spray it around the linkages and down the tubes with the blue arrow. it is to loosen a stickey float as you said, did you remove the bowls to get to the float? No



Your pictures and descriptions concern me. You said that you turned off the engine and looked in the carb bowls and they were half full, but you circled the venturis of the carburetor. If these were half full of gas, there is a serious problem. Can you check you picture and expound on this? You would have to take the sight plugs out of the bowls to check the level in them. Did you see liquid fuel sitting as a pool in the venturis? Yes, I looked down the venturies (red arrows) and a pool of fuel.
The black buildup where you noted is indicitave of backfire through the carb. This can be caused by a number of things including flooding.

Take another look at your picture, circles, and verify your information. Especially about fuel in both the primary and secondary venturis. The carb shown has no secondary accellerator pump so ther are only a couple things that would cause your problem, most likely the secondary needle sticking resulting in fuel spilling out the vent and down through the secondary venturis Yes, I would say that the secodary venturies (red circle/arrow) were half full of fuel. Does that mean it is stickimg as above? The best way to reslove this problem?

SWCDuke

Flooding is caused by too much fuel in the manifold. The ignitibility limits of an air-gasoline vapor mixture is an A/F mass ratio of about 6/1 to 17/1. Outside this range you can't light the fire.

Flooding can be due to driver error in executing a hot or cold start or too high fuel level, which causes fuel to drip from the venturi discharge nozzles after the engine is shut off. Since the engine is hot, this fuel will rapidly evaporate and can cause a mixture richer than 6/1, and the engine won't restart after a couple of minutes because the mixture is beyond the rich limit of ignitibility. So you have to go through the unloading procedure, which basically pumps air through the engine without adding additional fuel. This should purge the engine of excess fuel vapor, and once the mixture is within the rich ignitibility limit it should fire accompanied by a puff of black smoke out the exhaust.

Carburetors can be finnicky and tricky. There are a lot of little adjustments that must be correct for them to operate properly. My suggestion to all is to first have the appropriate service information for your car, which will contain all the particular adjustments for your carb, assuming it's an OE carb.

Next, for whatever type carburetor you have - Holley, Carter, Rochester - buy the HP book or other reference book for that type of carburetor. Such books explain the basic theory of how carburetors work including all the various subsystems and gadgets - idle, off idle, main, and power fuel metering systems including air bleeds; floats, chokes, choke vacuum breaks, unloaders, hot idle compensators, etc...

Duke

crw41

Have the book - gotta start reading tonight!

This is a better explanation of what I saw (actual picture):

The areas in red were about 1/2 full of fuel. The car was turned off and the fuel level gradually went down.

So, too much fuel at once:

Could my float have gotten stuck? Or, just the typical hot restart flooding problem?

ghostrider20

Those Tubes on the top are float bowl "Vents"

The 4 round "cups" in the center of the carb bores are "boosters".

The boosters feed the engine fuel from the float bowls, via the jets.

IF THE FLOATS are set to high, the fuel level in the float bowl will be too high, and the fuel will run out from the bowl, in to the "boosters" instead of being drawn in.

The float bowls operate on the same principle as a toilet bowl tank. Take the lid of your toilet and watch the operation. The Holley carb is the same, in principle.

Mark

SWCDuke

If you are saying that after shutdown the secondary throttle bores are half full of liquid fuel then you definitely have a problem - a serious problem, and you should not drive the car until it is corrected. Either the secondary float level is too high, or you have a serious internal leak in the carb.

Do this test. With the car on a level surface idling at full operating temperature, remove the air cleaner. Then shut down the engine. Watch the discharge nozzles in the booster venturis on both sides for evidence of fuel dribbling. It can be tough to see because surface tension may cause the fuel to cling to the booster venturi surface, but it will eventually form a drop big enough to fall onto the butterflies, and from there it will migrate into the manifold.

If this is the case, the float level for that side is likely too high. If not, there is an internal leak that is allowing fuel to seep into the throttle bore. The carb should be removed for a thorough inspection to find the leak and take corrective action taken.

Read your Holley book to understand the sources of possible internal leaks. Missing or incorrect components or incorrect bowl gaskets can be possible sources of internal leaks.

Duke

rgs

With that much fuel in the secondary, it is most likely a stuck float or needle/seat. You said that you earlier had a stuck float. I'd say it is time to do a little work. Based upon your information, I'd interpret that you have some knowledge of your carb but are in need of a little more before undertaking surgury. If you want to try doing things yourself, start with a simple replacement of the secondary needle/seat. This is done without dissassembly of the carb and a fairly easy operation. Good learning steps. If that doesn't cure the problem, the float bowl will have to come off to do an inspection of the float. If it is an original brass float, it may have developed a leak and no longer floats.

As mentioned earlier, you have a serious problem and should not operate the car till it is addressed.