Reply to "Webber Fuel Regulator"

I don't know really. Judging by previous experience, probably misinterpretation of the data on my part.

What I saw is that what shows as being the correct idle mixture on the "machine" does not work on the car.
I think it is that the idle circuit is also the middle circuit all the way up to about 2,800 rpms.
That makes that entire 1000 to 2800 range to lean if you try to clean up the idle.

All that was important "back when" is that the car ran at idle. That's all. It is a racing setup. It is t unable enough to make it streetable within a loose interpretation of the term streetable.

I have a dyno test result somewhere here that was done by Shelby on a 289 comp engine with Webers. Their idle is the same as mine and the main is much heavier.


If too lean at idle the engine will backfire incessantly at either the opening of the throttle or closing of the throttle.
I have blown out mufflers on closing the throttle because the idle circuit was too lean.

Mine idles leaner that a Holley 4779 but not a whole lot less.

The Holley will smart your eyes at idle. The Webers don't. Maybe they do and I'm just getting insensitive to it now?

I do want to try a 60f/80a idle combination and see what that does. I am told that it works but I have not tried it.

The last time I tried 60's was when I blew out the muffler baffles.
The case looked like a bomb went off in them with the seams split open.

I'm at 67/120s now. It's a heavy idle but the power is right all the way into the transition. The 67s have to be drilled out of 65s.

I hate playing with the idle circuit too. When you increase or decrease the size of the idle fuel jet, it effects the idle rpm. The idle set screws become unresponsive at some point and you can't get the car to idle under 1,000 to 1,100 rpm with 70 idle jets.

One thing with these carbs is that I am always influenced by what someone else has said they tried and thought worked and you can always go back and try another combination.

So far I always seem to come back to where I started off though.

You really have no collectors on those headers.
I don't know how that effects everything at this point. Also where you read the richness in the exhaust will likely effect the level. The collectors do have an effect on that just from scavenging alone, even at idle.

I don't know which is better to read. Probably doesn't matter as long as you use a constant location.

These are also carbs. There are some variables you are just not going to be able to tune out unlike with fuel injection.

It is an analog system vs. digital. Apples and oranges.