Bill:
Carb Piston lift is caused by th suction created when the Engine piston
runs its intake stroke. On its way down, the piston take a volume of
air with it. This air comes from the carb. On the bottom of the piston
are two holes.
These two holes are what makes the piston rise. The air flowing past
these two holes creates a suction in the dashpot area. Ths suction (or
low pressure) causes the piston to rise.
It's much easier to see if you have the carb piston and dashpot in your
hand. If you invert them, the piston will fall, and blow air out these
holes.
I just re-read and realized I used the word piston too many times. I
suggest the Haynes SU Manual.
By the way, you should see your pistons lift when you crank the engine.
Are they?
Thomas James Pokrefke, III
1970 MGB
pokrefke@netdoor.com
On Sun, 29 Aug 99 10:26:01 EDT
Bill Saidel <saidel@crab.rutgers.edu> wrote (and I quote):
> Hi all,
> Time for lesson no. 17 on the operation of a carb...
> Where does the lift for the piston originate from?
>
> The running saga goes like this: I did the Twist detox on a '76 and for some
> reason, after all was said and done, each time I tried ignition, the car
> chugged and never caught. Inspection showed that I immediately flooded it.
> (Well, 2 weekends worth of inspection.) Took the clean end of my trusting
> cleaning toothbrush and jammed it under the piston and it started right up.
> I should add that the end of the toothbrush also opened the throttle disk so
> maybe that is the element that allowed the start.
>
> In any case, I still want to know what provides the lift on the piston.
> Anyone know of a particularly good reading source on how these beasts work?
>
> Thanks,
> Bill
Thomas James Pokrefke, III
pokrefke@netdoor.com
Audentes fortuna iuvat
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