<VV> Poor Gas Mileage

[NicolCS at aol.com]

I suppose a "stuck open" high-speed enrichment valve is possible on a carb 
that isn't clean internally. In my experience, power valves get stuck IN their 
seat, not out. Normally both the pump check valve and the power valve return to 
their seat freely, assisted by gravity and vibration.  Note that only a small 
number of Corvair carbs have power valves; only 64-5 primary carbs. Your '67 
didn't come with PV carbs originally.  To check yours, locate the fuel inlet 
side of the carb, follow the long accelerator pump arm to the bottom and there, 
at the lower edge of the bowl, you will find an aluminum plug on a PV carb. 
The plug's head is about 1/8" in diameter.  No plug = no power valve.
Good hunting!
Craig

<snip>
Recently there was a post about poor gas mileage in a LM. While going 
through the service notes there was one that mentioned that if the Power 
Enrichement needle is misaligned, there is constant fPE low and there will 
be a 4-5 MPG loss. It also said the most common cause of misalignment was 
to turn the carb upside down to drain which would unseat the needle valve.
Padgett <unsnip>