Jet Black

[alfaparticle]

I think that it is not a jetting problem. Your jets are correct for your engine. You are getting too much fuel into the engine. High fuel pressure could cause this. You probably have the FISPA glass bowl combined filter/regulator. Pressure adjustment is by a screwdriver slot on the top. I do not have any detailed knowledge of which way to turn the screw or how they fail. You could check the fuel pressure by installing a Tee into the fuel line with a gauge. Webers work well at about 3.5 psi.
Another possibility is the cold start enrichment devices are either not fully shut off or are leaking. Loosen the clamps that fasten the thick wire to the actuator arms and make sure that the arms are all the way forward. They can also leak internally. Many people (including me) plug the holes that connect the devices to the carburetor throats. Someone, maybe George Schweikle, has a post that describes installing set screws to seal the holes. I used epoxy putty.

[tek]

Having spoken to the PO, he did say that the car ran excellently, but that it also began to spit and pop and lose power. He took it back to the overhaul mechanic and then the car ran well, for awhile. Then he described the same problem the car has now.
Thanks for the comment Alfaparticle. And I have checked out all the linkages to make sure they're correct. And I don't think the mechanical pump is overpressurizing the system.

[tek]

I was expecting a dramatic change, and I got it. Wow ! As soon as I installed them, and reset the idle (now at about 2 1/4 turns out on the screws instead of 3/4 turn) , it just settled down to a comfortable and easy 850 rpm idle. Taking alfaparticle's suggestion, I revisited the linkage and found that the accelerator cable had been secured at a point that it was causing the butterflies to hang up a few degrees, intermittently. This really played hell with trying to set the idle initially because I didn't find the hangup right away.
I've got 5 miles of brand new straight flat asphalt right by the house. From get go to 6500 rpm, not one hiccup, surge, or flat spot. I was expecting to lose a bit of power, but the engine now feels so lively, I'm not sure if I actually lost any. I didn't see one hint of black smoke, and the plugs appear to be right on the money now. I'll look at them now every 100 miles or so.
Comparing the .050 idlers to the .040, I'm thinking it looks as though they were drilled out(or possibly reamed with a welding tip cleaner: old jetting trick) because the visual light coming through the hole was greatly larger than the new jets.
Similarly, the new emulsion tube not only was a much smaller interior bore, but it has air emulsion holes staggered up the tube in addition to the radial drilling. The old F-16 was radially drilled on one elevation only. The new tube is obviously designed and crafted better.
The supplier inadvertently shipped 150 main jets instead of 150 air corrector jets. They'll send the correct ones free of charge.
But how nice to have a smooth engine hum at 2500-3000 rpm, at 10% throttle, idling down the road, without any crackling, popping, hunting,or sooty exhaust.

So thanks for the comments guys.
One other thing that has been on my mind is the apparent love for the sound and wrap of the 1300 engine. My redline begins at 5800 and extends through 8,000. I have no intentions of running it to 8 grand. I recall that the peak HP is around 6,000. But right at 6,000 the engine opens up and it sounds like it is good for at least another 1000 rpm. So you guys who wax nostalgic over the whine of the 1300, please chime in and tell me about where to drive this engine for performance. I've been shifitng around 6-6500. (wussy)

[tek]

Until Ed mentioned it, Ihad forgotten about the glass bowl filter. I kept it, but am running a clear plastic inline filter between the pump and the carbs. I've got a good pulse on it, but have been thinking more about replacing it with an electric. Preferences?

PS: Does alfabb have new owners, or just a new page?

[tek]

I just did a 30 mile run on the interstate at 5th/3500 rpm/80mph, running 4th to 95mph then shift up. Snmooth as silk. Then I did about 10 miles slow stop and go without getting above 3500 rpm. Smooth as silk.
And what a light touch on the throttle to maintain 80.
THIS is what i remember about Alfa Romeo.

[tek]

FYI: Full tank road test.
Weber DCOE 40/28
Main Jet 100
E Tube F11
Air Correct Jet 150
Idle jet 40/F9

10.43 Gallons
272 miles
85.5 Octane
Average driving.
26 MPG

Unless the existing jets and tubes had been tampered with, I don't see how the car could run right with 40/28
110/f16/220 50/f11. But that is the setup shown in Centerline Alfa's Weber section.

I could see bumping the 110's back in for a little more performance, but I'm really happy with this setup, and the plugs agree.

I'm now running a full tank of 91 Octane. I'll see if that makes much difference.