... on a Carter BBD. I've set all the carb adjustments as best I can, according to the rebuild kit instructions and the literature Dan provided in another thread. When warmed up, the engine idles nicely and runs great at low or high speed. It's just a booger to start cold. I fully believe it is the choke or choke pull off settings.

The choke mounted to the exhaust manifold pocket COMPLETELY closes the choke plate when on the high lobe of the fast idle cam. Should it do that, or should there be a slight opening for initial starting? I know that once the engine starts and creates vacuum, the choke pull off will open the choke plate to a gap distance I set with a gauge. I'm just wondering about the initial choke position.

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

Jerry
It should be COMPLETELY shut.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

This is why I asked...
This morning, it was about 35 deg. outside when I tried to start the engine.
I pressed the accelerator once to set the choke/fast idle and give it the initial shot of gas. I cranked, and cranked, and cranked... nothing.

Opened the hood, pulled the breather lid, and the choke plate was completely closed as I expected. The fast idle screw was also set properly on top of the high lobe of the cam. Everything looked good.
I put a slight bend in the choke rod to relieve a little tension (it, not me). Made sure the fast idle screw didn't move off its position, reached through the window to turn the key, and it popped right off. It was running a bit rough, but evened out better when I manually opened the plate slightly. It was still fairly dark outside, so I couldn't really tell if the pull off had done its job completely after starting.

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

Have you got the correct thick rubber gasket between the air cleaner and the carburetor? Is the air cleaner clocked correctly relative to the carburetor? If not, you may have interference between the bottom of the air cleaner and the choke lever, preventing the choke closing completely. This can be difficult to spot, because removing the air cleaner lid can clear the obstruction. You may want to remove the air cleaner altogether tonight after you park the car, then let it cool overnight and see how it starts up tomorrow morning without the air cleaner.

Bending the choke rod is usually not a good fix (unless what you're doing is unbending somebody's previous brutality to the rod). When everything's assembled and set correctly, it should work without needing new or different bends.

Also, check to make sure you're not on a goose chase — you'll need another separate morning to test this, but after the car's been sitting overnight and before you crank it, hold the choke open and operate the throttle linkage. If there's not a strong shot of fuel from the accelerator pump jets, the carb is emptying overnight, causing your extended crank time.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Have you checked the choke pulloff diaphragm? This might be ruptured causing (a) a vacuum leak and (b) the choke to stay closed and choke th motor for air.

Remember, this setup is exactly identical to what we had with the faulty BBD that was replaced, down to the same type of gaskets, choke rod, breather orientation, and I even swapped over the choke pull off when I found the "new" one to be leaking vacuum. It's the closest thing I can describe as a true "plug-n-play", with little deviation.

Are we in agreement that the choke plate should be COMPLETELY closed, as Frank suggested (not that I don't believe you, buddy). That's the only thing I can actually say that I don't remember how it was set with the other carb. I keep seeing in my mind a picture of a small gap when the engine was cool. When it cools down late this evening, I'll open it just a smidge and give it a try.

Dan, I mentioned this before in the other "carb" thread - when I pulled the carburetor top off, I was surprised there was very little fuel in the bowl. And again, this past weekend, while swapping to the newer rubber fuel line as you guys suggested, when I pulled the hose loose from the top of the filter, no gas poured out. There was no fuel in the short metal line leading from the filter to the carb inlet. I'll double check for a fuel squirt in the morning.

Where is the gas going? Wouldn't it still be under a slight bit of line pressure from the fuel pump diaphragm? Does that indicate a problem with the pump, or is the pump designed internally to allow fuel to leak back? How could it if the fuel line is full? So many questions...

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

The carb should be fully shut when the motor is off. If the float bowl is empty when you pull the air horn of the carb then you might have an internal leak which drains the carb and floods the motor, making it hard to start. Hard to say without being there.

Meaning what - throttle plates closed, gaskets sealed, screws tight?

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

I had a similar problem with my 84 dodge pickup. Runs and drives fine and would fire right up when warm but when it sat for a while it would crank forever before starting. Turned out to be a hole in the gas line right where it exits the tank. The fuel would leak back into the tank so I never saw a drop on the ground. How does your fuel filter look? One of the symptoms of my problem was constantly having to replace the filter.

Sorry, I wasn't clear. When the motor is cold and you depress the accelerator once, the choke butterfly valve should close fully and the fast idle screw should be resting on the fast idle cam, ensuring that the throttle is open enough for the motor to idle at 1200-1500 RPM upon first startup. As soon as the motor is running, the choke pulloff should pull the choke butterfly valve open roughly 1/4 inch, but the fast idle screw should stay on the same spot on the fast idle cam. As the engine warms p, the choke pulloff coil in the exhaust manifold should slowly pull the choke butterfly valve open and, at the same time, the choke linkage should move, rotating the fast idle cam so the fast idle screw contacts smaller and smaller steps on the fast idle cam until, once the motor is fully warmed up, the choke is completely open and the fast idle screw has been moved to the point where the fast idle cam no longer contacts the fast idle screw and the throttle is being held open by the curb idle screw. Better?

The fuel pump valves can indeed grow leaky with age and allow the fuel to run back down to the tank. There's even some documentation (which I have not confirmed) suggesting some pumps are built specifically to bleed the pressure down after shutoff to prevent percolation-induced flooding. Whether or not that's so, Chrysler did release a "flood-stop" kit for the slant-6 consisting of two brass fittings with small-diameter hose nipple coming off the side of each. These small nipples each had a tiny pinhole, and a hose connected them; after shutdown you could see the pressure squirting from the fitting on the pump outlet to the fitting on the pump inlet through the clear Tygon tubing connecting them. Engines so equipped start up fine after sitting overnight.

Sometimes little things can make a difference if the leakback thru your pump is greater than normal: if the fuel inlet going into the carburetor is horizontal or lower, it's easy for the fuel to siphon out of the bowl. Sometimes rotating the inlet fitting or line so the fuel has to go "over a hump" before entering the carb is all it takes to keep fuel in the carb overnight—sort of the inverse of the "P"-trap under a sink. Also, I'm not clear on whether you put a kit in this carb or not, but if not, a new inlet needle and seat might be a wise idea.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have never understood the theory of fuel being sphoned out of the carb, by way of the furl line. Most every carb I have ever seen, has the inlet needle/seat, above the fuel level in the bowl. If the fuel inlet is above the fuel level, it is not possible to get a siphon effect.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

And THAT is what is baffling me. After pulling the top off and finding the bowl virtually empty, I tried reasoning it out in the same way. The inlet/seat is just below the seam where the two carb halves mate. The TOP of the float is adjusted to 1/4" below that mating surface. The float is a good 1/2" - 5/8" thick, so that would certainly put its BOTTOM well below the needle valve.

Siphoning requires an absolutely air-tight seal with no vacuum break. Even if the needle seat was faulty, and the bowl was completely full of fuel, a siphoning condition would only be able to empty it to the level of the needle where it would begin to suck air. The bowl would then be approximately half full of fuel.

Come to think of it... when we first cleaned up the fuel line to re-install it, I tried to blow compressed air through just to make sure it was not clogged up. If I'm not mistaken (been quite a while ago), it would allow air to go through in only one direction. I wondered why and found what I assumed was a check valve on the fuel pump end. Anyone know this for a fact? If that's the case, wouldn't it prevent the line from draining back to the tank (assuming it is functioning properly after 35 years)?

The only other possibility I can see is that the heat from the hot engine vaporizes the fuel in the bowl and it is allowed to escape to the charcoal canister through the bowl purge. One of the carb kit items is a circular rubber seal that you replace on that little hinged "flapper gate" in a side chamber of the bowl. It is closed when the throttle is used, but it opens when idling (or engine not running) to exhaust the fumes. It's part of the emissions system that keeps fumes from releasing directly to the atmosphere.

I still have the old carb and I'll fill it with fuel to see if I can determine where it could possibly leak out sitting static. Unless proven otherwise, I have to discount the possibility of siphoning as the cause.

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

74 Sport,

The siphoning back would just be what is in the fuel line and filter between the pump and carb. As far as the carb goes, if the bowl is full per spec while running, then you have allot of fuel boiling in the carb during heat soak and loosing it through evaporation.

On my 74 when it was stock I used to hear the fuel actually boiling during heat soak on hot days and if I pulled the air cleaner lid could see fuel mist rising. After installing a aluminum heat sink/deflector under the carb and (2) 1/2" thick gaskets, one below and above the aluminum plate, it has stopped this from happening. I should mention that having the electric fan automatically kicking on during heat soak after engine shut off really helps too.

You may want to consider both mods. You can click on the red link below my name to see some pictures of the mods.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I have the same problem with my BBD. When it sits over night, it takes 2-3 tries to get it fired, but it always fires up the same. If its only been sitting an hour or so, it'll fire up immediately. It's progressively gotten worse over the last couple years.