RE: Pump Shot

[Eric Bryant <BRYANTE@ghsp.com>]

> From: dave.williams@chaos.lrk.ar.us
> Subject: Re: Pump Shot
> 
> -> A quick shot of fuel to overcome the drop in vacuum during a quick
> -> throttle opening..
> 
>  I suspect it's more of a little engine/big car thing.  Disconnecting
> the accelerator pump on my V8-converted '72 Capri did nothing I could
> tell.  Cars with SU side drafts have no accelerator pumps, nor do most
> motorcycles.

It depends on the carb.  With certain types of carbs, the accelerator pump
compensates for transient throttle conditions where the airflow "gets ahead"
of the fuel.  With motorcycle carbs, this can't happen because of the CV
slide construction, so most motorcycle carbs have no accel pumps.
Motorcycles also have the advantage of placing the throttle plate right
above the intake port, giving them a very strong vacuum signal.


Eric Bryant
mailto:bryante@ghsp.com
http://www.novagate.com/~bryante  
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