<VV> Throttle linkage

[Tony Underwood]

At 10:16 hours 11/19/2004 -0500, Levair@aol.com wrote:
>In a message dated 11/19/04 12:36:12 AM Eastern Standard Time, 
>tonyu@roava.net writes:
>
><< It is my humble opinion that the typical Carter AFB is one of the best
> carbs ever to land on any engine to ever mount a 4xbbl.    >>
>
>I agree that it is the right size but it will not corner at all. Which is
why 
>they are OK with the dragracing set.    

You indeed have a point.   For street aps, though, the AFB is hard to beat.   


>    The smaller of the Rochester Quadrajets (670cfm) will corner even with 
>slicks and the cfm is whatever is needed as it is totally progressive and 
>secondary flow controlled. 

Some AFBs also had secondary venturi controls via counterweighted butterfly
valves, worked well and eliminated bogging ala the Q-Jet.   However, the
450 AFB unfortunately didn't use these butterfly restrictions.   If only
the 450 could have been retrofitted with secondary controls...  but the
carb body itself is relatively small and there's too little room for the
extra hardware, and of course at the time this carb was in production, such
secondary controls  weren't necessary because it was never provided with an
engine as small as the Vair engine... 225ci was the smallest thing it ever
landed on.       

>    The primaries are triple venturies and the same size size as the 110 hp 
>Corvair carbs.,

Indeed they are, and offer excellent fuel dispersion...  the secondaries
are a bit large though (although plenty rich to help bogging), but thanks
to the flapper valve it's not a huge problem.    The Q-Jet does need some
education in mind in order to exploit it to best effect, and it's more
complex than the AFB, but it was produced in huge numbers and repair parts
are available at the corner grocery store and 7-11.   


>   The only disadvantage is you will have to acquire an adapter and modifiy 
>it so that it is still totally divided in the center (no huge plenum-

Yep...  little engines don't like big plenums much... hafta rev them way
too high to make use of the plenum most 4xbbls end up sitting over if not
split in the middle.       

>and 180 deg. tuned).


By the way...  the AFB *can* be corrected to endure turns.   It suffers
from a float bowl that's wider than it is long and fuel sloshes badly from
side to side in hard cornering.   People have corrected this to some degree
via baffles... but then again as you said, the Q-jet doesn't need this
sort of correction.     

On the other hand, this sort of float bowl is great for hard acceleration,
which is the field in which the later versions of AFB cut their teeth.
Again, application lends cause for function.   The end result is that I
certainly agree that a Q-jet can work better on a road course car than an
AFB would, while the AFB will live nicely on the streets and is easier to
tune... providing you can turn up a metering rod kit, which is available on
occasion from places like eBay.    

...if a 450 AFB was as easy to turn up as a little Q-Jet I'd have a few
450s on the shelf.   

But that wouldn't keep me from playing with a little Q-Jet next time I
stick an EICO intake on something.    I might wander to Davids house and
trade him something... I think he has one or two on his shelf.    


tony..