<VV> Re: LM carbs

[Tony Underwood]

At 09:07 hours 05/03/2006, BobHelt at aol.com wrote:
>
>In a message dated 5/3/2006 8:14:37 AM US Mountain Standard Time,
>tonyu at roava.net writes:
>
>I have  several of these carbs
>that I parted out, VAB screw stuck solid and  immovable.   A couple
>others that were stuck, but also in better  shape otherwise, got
>"fixed" by just dobbing the JB Weld over the slot  vents in the air
>bleed, plugged, forgot about it and all was  well.   Idle mixture then
>adjusted like any other carb, seemed  to run better.   I was happy.
>
>
>
>Tony and all,
>These valves were called Adjustable Part-Throttle (APT) valves by Chevrolet
>and were used in many other carbs besides Corvair AIR carbs. Thes 
>valves were
>set very accurately at the factory to meet emission requirements for off-idle
>  operation and to limit the idle A/F ratios.


I'll give them this much:

They're a much simpler reaction to emissions than the Mopar 
"Lean-Burn" carb mods.

>The factory locked these valves
>in  position because they didn't want anyone readjusting them. That 
>is why you
>are  finding these valves "stuck". These valves are not intended to be
>readjusted  after they left the factory.
>Regards,
>Bob Helt


Some were staked a little more tightly than others...  ;)   With 
dedication, you can crack them loose without stripping metal off the 
screw.   Of course, some of them were plugged with what looked like a 
plastic screw that was usually destroyed when you tried to turn 
it.   Then there were the others with the screw simply time-welded 
stuck and nothing would allow it to turn; it cracked and broke first.

This, while attempting to "convert" the carbs into non-smog variants 
via mix and match of components during carb salvation parties on 
those off-hour weekends when it's raining and there's nothing else doing.


tony..