32/36 tuning guide?

[Nut124]

Why so rich? Detonation? According to "science" 14.7:1 is ideal.
I have been trying to dial in my carb for my 1438 so I installed a wideband O2 sensor gauge. With that in mind these are my numbers: Idle - 13.20, 2000 rpms 14.1, 3000 rpms 14.50, 4000rpms 16.8, 5000 rpms 14.50. These readings were taken in the driveway, not under load. I know my 4000 rpm number is high so I was going to increase the secondary main by 1. So are these to high? Should I richen up the jets and get hotter plugs, so I don't foul them?

Carburators are not perfect devices. They have multiple metering circuits that provide fuel at different engine speeds, load conditions. These circuits are supposed to overlap and the engine is supposed to smoothly transfer from one circuit to the other. In reality though, as one tries to lean the engine out, gaps, dead spots start to appear in the transition points and driveability is hurt.

JonChristine may have excessive static CR and detonation risk. Lean runs hot. The extra fuel in richer mixture helps cool down the pistons, chamber.

Reving the engine on the driveway is not a good way to assess AFR. 4000rpm at zero load is not a feal life use case. If your wideband is working, I'd drive around and watch it. Watch going lean under power, not safe. At WOT, I'd try to stay below 13.5.

Not sure what carb you have but I would assume it is a progressive 2-bbl.

In your no load test, the only circuit functioning is likely the primary bbl idle/progression circuit. It affects idle and operation at very light throttle at very low speeds. Controlled by the idle jet. Even at 4000rpm no load, the primary main circuit is likely not engaged. Certainly not the secondary. You could watch the throttle butterflies as you increase no load rpm. The second bbl is likely closed at 4000 no load.

The primary main jet controls AFR at low/medium speed cruising. The secondary main jet and air corrector control AFR and med/high speed and WOT. You can test the limits of your primary main circuit by disabling the secondary butterfly or by removing the secondary e-Tube/Jet stack. I'd guess you could drive around town nicely and not miss the secondary as long as not HWY nor stepping on it.

[70spider]

Well I did try to drive him the day before but the car ran so horrible after a few miles I barely got him back to the house, the afr readings were over 16. So today I tried to richen up the jets a bit and see were that takes me. I came across this thread to see where I need to go. My engine isn't exactly stock I put high compression pistons and the head has larger intake and exhaust valves as well as ported and polished. So with all of that I'll try to drive him again to see how far I need to go with the jets. From reading other carbureted car forums your assessments are on the mark, running the best between 12.5 to 13.5 afr.
Thanks

[Nut124]

What is your ignition timing?

Incorrect float level could cause very lean running.

What carb model is it?

[70spider]

What is your ignition timing?

Don't have a number, my old distributor bit the dust and I had the computronix electronic hanging around so I put that in for the time being. It should be at 5-6 degrees if I installed it correctly. Don't have a timing light, Santa came up short this year.

Incorrect float level could cause very lean running.

when I had the carburetor off I checked the float level it was pretty close to 51 mm holding it vertically.

What carb model is it?

Weber 32/36 DFEV from redline, the old chinese one tried to kill my car.

The jets are pretty close to the factory settings with the idle jets being a little leaner, I recently moved from near sea level to 6000 ft. so I leaned out my jets according to LC Engineering's guide to high altitude tuning but since went back to what I was running before.
This is my current set up:
Idle Jets; Primary 45 Secondary 40 Main Jets: P 137 S 145 Air Correctors P 165 S 160

[Nut124]

Ignition timing really needs to be checked and adjusted with a timing light, always. You can get an adjustable light for about $50. Dial in the advance and look at the TDC marks. Your timing could be way off. Too little advance runs ok but weak, low power. Also can overheat ex valves and seize them Too much timing will start to knock at higher rpms as the dizzy advances the timing. Too much timing can wreck the engine in a hurry. You also need to know what 123 curve you have in for total timing. Should be 36.

Your jetting seems in line with factory except the idle jets seem small.

I'd put in the redline original, bigger idle jets, dial in the ignition timing and get it running good, even if rich. Rich, anything above 10 always runs ok. Once you have it running OK then start tweaking, one jet at a time. Lean, 14+ never runs OK.

[70spider]

I took the carb off just to check it over after watching several vids on float adjustment. Turns out my needle valve had 0 movement, lol carb is only 2 years old. Good thing I bought a rebuild kit some time ago. Also, when checking the fast idle adjustment I noticed that the secondary butterfly wasn't moving at all. It was frozen shut. I sprayed it down with a bunch of WD-40 and it loosened it up a little. It is still a little tight. I'll figure out how to remove the pivot shaft so I can clean it with emery cloth. Another thing the primary butterfly wouldn't close all the way exposing the progression port. This is probably why it was hard starting, acting like it was flooded. Man Webers are a pain. I have had my Edelbrock for 8 years and only changed the metering rods when I moved to 6000ft.

[Nut124]

The primary butterfly closing position is controlled with the idle speed screw. It sets the stop for the primary close.

Was your needle valve stuck open or closed? You sure about this? If open, engine would flood at idle, gas pouring in. If closed, it would not start at all.

The secondary butterfly is actuated either by a mech link or a vac actuator. It should not start to open until the primary is about 1/2 way thru it's rated flow.

I'd get a Weber manual. The Haynes is better than nothing.

[70spider]

The primary butterfly closing position is controlled with the idle speed screw. It sets the stop for the primary close.

I know but it was so gummed up it wasn't allowing it to close all the way exposing the progression port. I cleaned it up a little and now it covers the port.

Was your needle valve stuck open or closed?

When I placed the top of the carb on the bench the weight of the floats depressed the ball all the way down, therefore there was no downward movement. I put the new one from the kit and it actual supports the float with the 2mm of travel it is suppose to have when depressed. And no the car did not want to start most of the time.

The secondary butterfly is actuated either by a mech link or a vac actuator. It should not start to open until the primary is about 1/2 way thru it's rated flow.

It wasn't even opening when I open the throttle all the way. The pivot shaft was so gummed up it wouldn't budge. I remove the throttle linkage and had to use needle nose pliers to open it. I cleaned it up a little and now I can turn but hand but still a little tight.
I am soaking it in Berryman's B12 overnight, all I had, and see if things move more freely tomorrow. The manual might be worth it.

[70spider]

https://www.rcnmag.com/tech/weber-carbs says this:
"Truthfully, Webers can be extremely unforgiving—but only when not set up properly in the low-speed circuit. They have to be jetted exactly right. Later on, a lot of guys who tried running Webers on the street suffered because of it, giving up and selling them in utter frustration. Things like fuel pressure, float levels, ignition timing, low-speed jetting, and emulsion tubes—it was all too much for the average guy who just didn’t have a complete understanding of how to work with these carburetors. And, there was really nobody to ask."

[18Fiatsandcounting]

Come on guys, Webers are awesome carbs, and it's not so hard. At the risk of getting booted off this forum:

[/rant on]
Fuel pressure? 2 to 4 psi is fine.
Float level? Adjust so you have about an inch of gas in the float bowl.
Emulsion tubes? Almost any emulsion tube will work, unless you are tuning for peak power only between 7200 and 7400 rpm.
Main jets? Pick a size to get a nice light brown or light grey on the spark plugs. 135 almost always works.
Air correctors? Almost no difference for most applications. See "Emulsion tubes" above. Start with 180 or so.
Idle jets? This does make a difference. Pick a size that gives a nice idle with the idle mixture screw turned out 1 to 2 turns.
Chokes? Set properly, they work fine. Set improperly, they don't.
Vacuum secondary? Yes, these often fail and are a weak point. Get a Weber with a progressive (mechanical) secondary.
All other diaphragms? Emissions and other related stuff which rarely works after 40 years. Usually not necessary.
Air leaks in the intake system? Yes, can be a real issue, but that's not specific to Weber carbs.
Plugged passageways? Yes, can be a problem. Clean thoroughly and blow thru every passageway with carb cleaner.
Warped base flange where the carb bolts to the intake manifold? Yes, can be a problem (see above under "air leaks"). Fix as appropriate.
[/rant off]

-Bryan

[70spider]

Come on guys, Webers are awesome carbs, and it's not so hard.

You are right.