<VV> Carter YH choke "blink"

[Doug Mackintosh]

Here is what I observed on my daughter's Spyder (air cleaner element removed, no 
load):

Before warm up: When throttle is opened quickly, the choke plate closes 
slightly, then returns to former position.
After warm up: Choke is wide open; when thrtottle is opened quickly, the choke 
plate stays wide open.
 -- Doug Mackintosh
Corsa member since 1996
Corsa/NC member since 1996, Virtual Vairs member
Corvair owner 1969-1971 and 1996-on 




________________________________
From: "BobHelt at aol.com" <BobHelt at aol.com>
To: dougmackintosh at yahoo.com
Cc: virtualvairs at corvair.org
Sent: Sun, 29 August, 2010 20:43:18
Subject: Re: <VV> Carter YH choke "blink"



Doug, 
Something doesn't sound right. Once the engine is warm, the coil is out of play 
and the vacuum holds the pull-off and the choke open. Now if an acceleration is 
called for, yes the vacuum lowers and the pull-off is not held as before, but 
the choke remains open since the plate is off center and the airflow (and 
increased airflow) keeps the plate fully open. so I don't see how a blink, or 
much of one, can occur. 

However during warm up, the choke plate is held open by the pull-off until the 
coil further opens the plate. if however, the engine is accelerated at this time 
the pull-off will allow the choke to slightly close because of the lower vacuum. 
At the same time the choke plate will counteract this by tipping slightly open 
because of the increased airflow, thus likely preventing a blink. Maybe this can 
cause a cough????

Regards,
Bob Helt 

In a message dated 8/29/2010 2:15:08 P.M. US Mountain Standard Time, 
dougmackintosh at yahoo.com writes:
As to why I think the blink happens when the choke is fully open, in a VV 
response to a query about a cough on acceleration, Craig Nicol said 
"Acceleration enrichment in the YH happens through the usual accelerator pump 
squirt, but that is the secondary system.  The primary system is the choke 
plate, which for lack of a better term, "Blinks" for a moment when the engine 
vacuum drops at the sudden opening of the throttle. After that, the pump shot 
occurs, which continues the enrichment." I don't think there was any suggestion 
that either the problem or the cause were restricted to cold engine conditions.