<VV> Carburettor question(s)

[BobHelt at aol.com]

In a message dated 6/25/2009 12:06:28 P.M. US Mountain Standard Time,  
david.neale3 at ntlworld.com writes:

I am  somewhat bemused by the Power Enrichment Needle.  On Page 6M-4 of 
the  '65 chassis manual, it is shown, rather vaguely, as being inserted 
inside  the spring against which the accelerator pump pushes.  Looking 
down  into the well, there appears to be no natural seat for the power  
enrichment needle.  It all seems rather odd.

I have a pair of  spare primaries from another '65 car, which I know were 
is service for a  couple of years.  The power enrichment needles are not 
present, but  the car ran well enough nonetheless. 

Would one of you knowledgeable  people please advise me regarding just 
how that needle seats; and what  effect one might experience if the 
needles are missing?

Many  thanks,




hello David,
Well that shop manual diagram is somewhat of an optical "de-lussion." It  
isn't very accurate. But you should first know that just because the vertical 
 passage for the power enrichment needle is in your carburetor, it  DOESN'T 
mean that you have a PES. Many carbs were built with this hole, but  the 
pes wasn't completed with the necessary accompanying passagways. But if your  
carb really has a working pes, then you will be able to see the seat at the  
bottom of the hole for the needle (with a flashlight). To be certain 
whether you  have a pes, look for the aluminum plug on the outside of the body 
where the  internal restriction was inserted. i don't have a photo of this 
handy so  please see the one in my carburetor book.
 
As to why the PES was installed, Chevy added this enrichment feature in  
advance of the total carb re calibration done for 1966 whereby the main jet 
was  made leaner and thus provided better A/F ratios for cruise, and richer 
mixtures  for power and high speed performance. Some carbs in 1964 ran lean at 
high speeds  and the 1965 pes was to prevent that from happening.
 
As for missing needles, if they are not supposed to be there and are  
missing, no problem. If they are supposed to be there and are not, your engine  
will run VERY rich under most cruise conditions and give poor misleage.
Regards,
Bob Helt
**************Make your summer sizzle with fast and easy recipes for the 
grill. (http://food.aol.com/grilling?ncid=emlcntusfood00000005)