im stumped

[jerryt]

I have a L16 carburetor that baffles me. I rebuilt the carb just a cleanup and new gaskets.  Before the rebuild the carb didn't operate well. Now the car won't start unless I put a little carb spray. I let it run and then shut it off. After 5 minutes I can start it again. But when it sits like for a couple of hours it won't start. I took off the filter and replaced it. I also took off the hose at the carb inlet and I get gas. The glass float bowl seems to have too much fuel. Im trying to figure it out before buying another carb. Any ideas?

Thanks

Jerry

[datzenmike]

Fuel level should be at the line on the glass or if no line then in the middle. Adjust the float drop to set the fuel height and call me in the morning.

[jerryt]

to rest the float level you have to take off the carb and sight glass?

Thanks

Jerry

[datzenmike]

Carburetor stays on. Put a rag in front of the carburetor to catch the gas. (also catches anything dropped) remove the three screws, the bezel and the glass. Slide the float off being careful to catch that brass spacer that's between it and the glass. There is a tang on the float top where it touches the needle valve that sticks down into the float chamber. Bending it ever so slightly up will shut the fuel off sooner as the float rises up. Likely this will require several tries.

 

You can do it by taking the carburetor off and holding it upside down letting gravity substitute for the lifting of the float by the gas. The float top should be even/level or horizontal with the top of the float chamber when set properly.

[jerryt]

The fuel level when you look at the level is 1/4 inch from the the top of the glass. So the fuel level should be half way thru the inspection glass? And another part on the the choke blade should they be closed upon cold start? I’m just trying to think of everything before taking off glass inspection window.

thanks

jerryt

[datzenmike]

Yes half full.

 

The choke will normally be closed when the engine is cold. It will have no bearing on setting the float height.

 

 

The post that the float is hinged on has a small brass spacer between the glass and the float arm. It's the first thing to fall off when the glass is removed so watch for it. Have a large rag under the front of the carburetor to catch it and the gas.

[jerryt]

Ok please follow my logic and tell me if I miss the mark. When I try to start the engine cold it cranks but doesn't fire. But if I squirt a little starter fluid it fires right up.

1 I removed the gas line to the carb and observed the flow to the carb. It was less than I expected. 

2 The choke blade doesn't close on initial start up

3 I think the float level is around 3/4 full thru the glass inspection

4 It really seems like I have a blockage on initial start up when cold.

5 I was thinking make sure choke plate is closed on initial start. Check to see if I smell or see fuel going into carb. And let pinch off the supply line to the carb and run all the gas out of the carb and let pump spin to see how the supply works.

6 It really seems like I have blockage somewhere. Like needle seat supply line or to much air because choke is wide open .

What do you think? 

Jerry

[datzenmike]

Gas flow to the carburetor is of no importance when starting as there is (or should be) sufficient gas stored in the float chamber for starting and you could probably drive a few blocks on it even if the fuel pump were not working.

 

The carburetor mixes gas with air, but it's a mass of very small particles. For an engine to run the gas must evaporate into a vapor on the way to the combustion chamber. To become a vapor the solid gas particles must absorb some heat to do this and this is called an endothermic reaction. Pour gas on your hand and blow on it and it evaporates but it feels cold. On a warm engine the intake, the head ports, the intake valve, combustion chamber and the piston provide that heat and everything runs normally. This is why it starts properly when warmed up. When cold an over rich condition is used so that there is a better ratio of evaporated gas in the air. This is done by using a choke that restricts air flow increasing the vacuum around the venturi and sucking more gas in.

 

When starting a cold engine the first thing to do is step on the gas. This releases the interlock blocking the choke flap from closing and it also operates the accelerator pump that squirts raw fuel into the intake. On exceptionally cold days 2 or more pumps of the gas pedal will help.

 

So, take your air filter off and watch while someone works the throttle. Does your choke close when the engine is cold and you step on the gas? It should. 

[jerryt]

ok I will have my wife step on the gas pedal while I look into carb. The carb has a manual choke. so I should unhook the choke cable to see how the choke flap closes at cold start. Is this the correct thinking?

Thanks

Jerry

[datzenmike]

NO! I ass-umed  it was an automatic choke, my bad.

 

Instead press the throttle down and pull the choke out then go check to make sure it closes before starting.

[jerryt]

Okay thanks. Before I take off the glass bezel the fuel level is a quarter of an inch from the top of the top. I was thinking if the throttle blades on the choke side would this cause cold starting problems? 
thanks

jerry

[jerryt]

Okay I got the car to start. The throttle blade was wide open. I pushed on the throttle blade it closed to about 3/4 closed . I hit the key and it started. Evidently it had been sitting for so long it stuck open. So I waited a couple of hours and tried again. It started right up. Thanks for all the help. 
thanks

jerry

[datzenmike]

Spray down all the linkages on the back of the carburetor with WD-40 and work them back and forth. Hold the throttle part open to release the interlock and have someone pull the choke on and off while you watch what moves.

[Stoffregen Motorsports]

You can even apply a tiny bit of grease in the linkage slots, to help loosen things up.