Topic: 350F air screw theory and practice.

[finkbuilt]

I've searched, but can't find it.

Does the air screw setting only affect the idle circuit?  or does it change the mixture for all RPMs and throttle positions, loads etc.

Also, while I have you - To remove the alternator cover - for polishing - do you take off the 3 inner screws?  It didn't "fall off" after I removed the outer screws, but I couldn't get the inner screws to budge withe the impact, so I thought better of whacking on them and saved the polishing for another day.

thanks

[HondaMan]

I've searched, but can't find it.

Does the air screw setting only affect the idle circuit?  or does it change the mixture for all RPMs and throttle positions, loads etc.

Also, while I have you - To remove the alternator cover - for polishing - do you take off the 3 inner screws?  It didn't "fall off" after I removed the outer screws, but I couldn't get the inner screws to budge withe the impact, so I thought better of whacking on them and saved the polishing for another day.

thanks

The air screws have 'authority' from idle to 1/4 throttle. They overlap with the carb slide's cutaway from 1/8 throttle to 1/3 throttle. The needle(s) in the slide(s) start working with the cutaway, and fall off at 3/4 throttle. From 3/4 to 7/8 throttle the slight mixture difference is just from air flow, and the last 7/8-to-full doesn't do anything to speak of, unless the fuel flow to the float bowls can be increased (which is hard to do with a gravity-drain system like these: just make sure all the vents in the tank and carb bowls are all open). That's why the last little bit of throttle doesn't seem to do anything.

If the "inner screws" you're talking about are the 3 in the center-ish area of the alternator cover: those hold (held) the field coil in place, inside. If you removed them, you'll have to remount it when you get it apart. For the cover: use a bounceless plastic weighted hammer, smacking it near the screw holes, to loosen. There are one or two dowels (and 35+ years of crud) holding the cover tightly to those dowels. Clean them well when you get it apart.

[TwoTired]

Here is another way of thinking about it.  The pilot circuit provides enough energy for the engine to tick over at idle.  For arguments sake let's assume that is 1/4 HP.  At full engine power there is enough energy coming in to make at least 30 HP.
Yes, the pilot system has some effect at full power and other throttle settings.  But, the ratio of dominant effect diminishes as the throttle is opened further.  A 1/4 hp contribution isn't very significant when the engine is making 30 HP.

Cheers,

[finkbuilt]

Perfect, thanks fellas!