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She must be tuned/jetted too rich to idle perfectly stone cold, once you have actually managed to start it.

But lets solve one thing at a time ...
Pete
 

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Discussion Starter #23
She must be tuned/jetted too rich to idle perfectly stone cold, once you have actually managed to start it.

But lets solve one thing at a time ...
Pete
That's exactly what I'm thinking... It shouldn't be this good stone cold (once it starts), over-rich masks a lot of issues....and once warmed up if it idles 30 seconds in the garage you need to exit in a hurry or you will pass out ;-) I'm gonna play with it a little more (haven't had it long enough to want to drop it off at a shop just yet), yank the modern stereo and possibly the A/C stuff, then take it to my local guy (mostly Porsche/Merdeces but a carb is a carb!) - if all else fails there's an Alfa specialist a little further (but he's the one who tuned it as is, so I'm not running there first...)
 

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So, click on the key, but do not crank until your fuel pump nearly stops clicking. Then, 3 - 5 pumps on the accelerator and THEN crank.
What he said. I don't think I've ever come across a carb'd Alfa that starts like an injected one. Run the pump until it slows down, pump the pedal a couple of times, and then turn the key. That is what I always thought was normal starting procedure for a carb'd Alfa.

bs
 

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What he said. I don't think I've ever come across a carb'd Alfa that starts like an injected one. Run the pump until it slows down, pump the pedal a couple of times, and then turn the key. That is what I always thought was normal starting procedure for a carb'd Alfa.

bs
I understand that part, same on my other carburated cars, what I was curious about was that after a week of not running, it seemed to take over a minute of fuel pump ticking before it would even try to start, that seemed excessive to me... I'm OK with the knowledge acquired here, I think... Thanks all !!!
 

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I understand that part, same on my other carburated cars, what I was curious about was that after a week of not running, it seemed to take over a minute of fuel pump ticking before it would even try to start, that seemed excessive to me... I'm OK with the knowledge acquired here, I think... Thanks all !!!
I had similar problems when I used a bendix fuel pump with a tank with a top fuel outlet. I once had to pressurize the tank with a leaf blower to prime the pump. I no longer have this problem after I switched to a Carter vane pump. That is why I asked in an earlier post about your pump, tank outlet and filter placement.
 

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Yes time to confirm/check your pump flow rate ...
Pete
 

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We all have our opinions, but posts #5 and 18 are two that square with my Alfa-Weber experience. Both Gordon and Jim are trustworthy sources of ancient Alfa wisdom (Oh sorry guys, did I just type that you're old? Well so am I.)

Fuel pressure is critical, as Gordon explains. If the fuel pump your car uses doesn't shut off or slow down, you'll wait a long time before trying to start the car. I turn on the key, buckle my seat belt and, by that time, am ready to pump the throttle three or four times. I live in the Pacific Northwest, have a high compression engine with Weber 45s and no choke. It always starts, but it takes a little throttle pumping until the engine catches. A choke might make it easier, but what's the fun in that? If you are looking for Weber tuning info, this link will provide a very good start: Daves home page
 

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Discussion Starter #29
I'm OK now.. I think it was a more a procedure thing for a converted car. I will get the choke connected and the carbs leaned out a bit, however... I was confused by the ticking of the pump that was unchanging no matter how long I waited, and the need to pump the gas pedal or not on an electric pump system... Right now (when it's been sitting a while), if I wait for 10 seconds of ticking and pump the pedal a few times it will *almost* start the first time.. Second time is generally good with a few more pumps... I will refine the process as I go. I've also been driving it more ( and not letting the bowls evaporate so much) now that I fixed a couple of electrical issues and modified my gas pedal and seat angle... I actually *want* to drive it now ;-) I'll occasionally go get the kids at school with it, they love "the red car"... Thanks for the help !
 

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... however... I was confused by ... the need to pump the gas pedal or not on an electric pump system ...
Hmmm, yes are you confused as the gas pedal and the electric pump system are NOT related!

All the fuel pump, electrical or mechanical, does is full the carburetor float chamber which (the level) is controlled by a needle valve. This has NOTHING to do with how much fuel is supplied to the engine, ie. if you do NOT touch your throttle/accelerator/gas pedal, and the engine is not yet running, NO fuel will be supplied to the engine.

So the reason you need to pump the throttle pedal is to make the accelerator pump in the carb's squirt fuel into the inlet manifold and therefore combustion chamber. This extra fuel helps obtain the correct mixture to start a cold engine, ie. considerably rich.

I think you are confusing modern fuel injected starting procedures, ie. you do not touch the throttle pedal as the computer sorts out the starting parameters. Even though the fuel pump still does not directly fuel the engine, it just supplies fuel to the injection system that then supplies fuel to the engine.

Conclusion: fuel pump does NOT control combustion chamber air/fuel ratio.
Pete
ps: If she is really running rich once fully warmed up, I'd be sorted that out quick smart. Very unhealthy for an engine and causes premature wear.
 

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Fuel pump and mixture

Conclusion: fuel pump does NOT control combustion chamber air/fuel ratio.
Pete
ps: If she is really running rich once fully warmed up, I'd be sorted that out quick smart. Very unhealthy for an engine and causes premature wear.
Actually it can and often does if fuel pressure is higher than the needle valve can control. That level is a function of both needle and seat design (several designs have been used, float type (brass or plastic) and the condition of those floats.

Look in the air box after driving, a wet area (gas) indicates too high a fuel level. But before you mess with fuel level, reduce the fuel pressure by a couple of pounds.
 

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Actually it can and often does if fuel pressure is higher than the needle valve can control. That level is a function of both needle and seat design (several designs have been used, float type (brass or plastic) and the condition of those floats.

Look in the air box after driving, a wet area (gas) indicates too high a fuel level. But before you mess with fuel level, reduce the fuel pressure by a couple of pounds.
I have been dealing with this issue after switching from 40DCOE116/117 to 45DCOE152 with brass floats. The new Webers need more pressure but give them a little more than necessary and the motor runs rich. There is a fine line between fuel starvation at high load/high rpm and running too rich.
 

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There is some poor information on this site at times even if people mean well. If your carburettors are dry after sitting over night, or even for a few days, you have a problem.
Have you checked your ignition system?
 

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Actually it can and often does if fuel pressure is higher than the needle valve can control
I'm talking principles.

If the needle valve cannot handle the pressure, IMO something needs to be altered to fix that.
Pete
 

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I've recently fitted Weber DCOE 138/139 carbs. Find the choke a great help when starting from cold, first flick of the key most times, but don't have the throttle open when turning the engine over. I wondered what the noise was when starting on choke, and from what I can tell the cold start mechanism draws air as well as adding fuel so even a partly opened throttle will reduce the effect. Once started a couple of blips of the throttle, choke pushed half way in and idle is good, once on the move choke full home. Also found the hand throttle useful if I need to leave the car ticking over for any great time when cold and helps to get it up to temp quicker. Agree if the float bowls empty that the fuel must be leaking somewhere it shouldn't. Worth also checking those spark plugs as too much soot build up will only make things worse.
 

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The "choke" on DCOE's is actually an enrichment device that pulls mix from "starter jets" by opening an air passage in front (engine side) of the closed butterflies. Now I do suffer deafness from F-4's in the Air Force, gunfire, and race engines PLUS age. I'm not aware of noise differences FROM DCOE's enrichment on or off.
Often owners forget to close the enrichment mechanism, and drive that way. This is somewhat Ok, because of the way the device works, but NOT a good plan, for a number of reasons. The enrichment device was well designed, and has a "backfire-pop" venting system designed into it.
It's not simply a choke.
Does this help?
From my experience.
 

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Okay... Took a look and the bowls seemed OK after 2 days of not running... I cranked it for giggles, and cough-die. Let it pump 10 seconds and pumped the gas pedal 4 times: it started... Progress... Will look this week end if I don't drive it till then, I want to see if those bowls dry up !

Pic attached for the adapter plate question..
I had a problem filling both carbs using the return hose to the tank. Mine is a 1974 SPICA to weber conversion. Never needed choke but good to have.
 

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I have had 8 cars with Weber DCOE series carbs and all start easily on the first try regardless of weather and if the engine is warm or cold. That includes a high strung 12.5:1 race motor, a very low compression Nord (worn out rings), and a Weber than drained dry over a couple days (leak in bottom cover). None have had the cold enrichment circuit hooked up.

I agree with the many posts suggesting (1) check your fuel bowls to see if they drained dry over 48hours. Easily done via the jet cover (look down the emulsion tube with a small flash lite). If it’s low then you need a new seal on the bottom of the carb (as previously posted).
(2) then turn on the fuel pump and time how long it takes for the initial pound ticking to quiet down. If it takes more than say 5-10 sec the gas in the fuel lines may be draining back into the tank (put a anti drain back value in the fuel line, or the pump lacks flow capacity.
(3) every dCOE equipped car I’ve owned starts easily if you follow the instructions others have posted.
(A) let the pump run to fill the carb fuel bowls (5sec)
(B) pump the accel pedal to the floor (push down, and hold for. 2 sec). The race motor needs this done twice. Some cars only need it done once.
(C) hold the throttle open just a tiny bit (10-15% of full throttle) with the accel pedal and crank it over.
 

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had a problem filling both carbs using the return hose to the tank. Mine is a 1974 SPICA to weber conversion. Never needed choke but good to have.
The best plan with a SPICA-Weber conversion is to remove all of the SPICA fuel feed and replace it with a good low pressure, high volume pump mounted as low as possible and close to the tank that feeds a Filter King regulator set at 2.5 - 3 psi. No need to pay big bucks for the pump as you can buy a Carter P4070 for $35. Electric Fuel Pump Pump with 1/4" NPT Inlet and Outlet E8470 P4070 | eBay
 
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