<VV> [fastvair] Carburetor mystery--Update

Sat Mar 21 12:46:36 EDT 2020

Mentioning the obvious based on what Hugo said... Are your putting the
distributor advance vacuum hose and caps back on the carb ports? Getting it
running fast enough and it should run, even if open to atmosphere.
If on the racing carbs, you have idle and transition ports, and you checked
passageways to them, did you check to see if the little holes/slots are
open? The ones in the bore wall of the carb where the throttle plate sits. I
presume you have the holes unless you have R Davis carbs with slots. And the
idle needle valve is set more or less open enough to run..
Absolutely fill the bowls with fresh gas before installing the top with
floats. Float inlet needle is not sticking... 
When racing carbs are installed, did you inadvertently "rearrange" the
linkage such that the throttle plates are way off at start up (although it
would seem to me it would start and race...)?
Chuck S 

-----Original Message-----
From: VirtualVairs [mailto:virtualvairs-bounces at corvair.org] On Behalf Of
Hugo Miller via VirtualVairs
Sent: Saturday, March 21, 2020 11:28 AM
To: virtualvairs at corvair.org
Subject: Re: <VV> [fastvair] Carburetor mystery--Update

I have lost the original post, but did he not say that the engine would 
not run at all? I'm no expert on these carburettors, but I'd be 
struggling to think of a fault that would stop the engine running on at 
least some of the jets. Unless it is the float valve of course.
I did once come across a car with similar symptoms - it turned out the 
be the float valve had unscrewed enough that the fuel level was so low 
that the car wouldn't run.
I know it sounds perverse, given the logical train of events we are 
presented with, but as they say, the first thing you should check on the 
carburettor is the ignition.

On 2020-03-21 12:50, jryall--- via VirtualVairs wrote:
> The known fact that both engines run well on stock carbs indicates
> that the problem is not in the engines nor the fuel system.  That
> means that the problem is in the bored out race carb system.  
> Although
> the carbs appear to be clean, there is still something wrong.  The 
> gas
> lines, inlet filters jets and passages in the carbs could still have 
> a
> clog that you cannot see. I would look for someone with a big enough
> ultrasonic cleaner to thoroughly clean out the carbs and associated
> fuel lines.  Perhaps Wolf Enterprises has the equipment to do this
> service for you.  There might be someone local with an ultrasonic
> cleaner.  Engine re-builder, engine tuner etc. The good news is that
> you can still run the car at track events using stock carbs! John
> Ryall
> ---------- Original Message ----------
> From: "'Brian' bmoneill at juno.com [fastvair]" 
> <fastvair at yahoogroups.com>
> To: VirtualVairs at corvair.org,  fastvair at yahoogroups.com
> Subject: [fastvair] Carburetor mystery--Update
> Date: Fri, 20 Mar 2020 23:38:07 GMT
>
> First of all I want to thank everyone who gave comments and advice
> the best I have ever seen to a question posted on the net.  I took
> every one of the suggestions very seriously and followed up on them.
> Here is what I have found so far in no particular order.
>
> Idle circuit-- every passage on the idle circuit was scrupulously
> clean I found absolutely no restrictions.
>
> Venturi cluster-- all the Venturi clusters are also scrupulously
> cleaned and again no restrictions.
>
> Idle siphon tube-- the idle cluster siphon tubes were also cleaned
> and again no restrictions.
>
> Adding gas== it was suggested to pour gas in while the engine was
> running and see if it had any effect.  Was very difficult to do
> because the engine dies so quickly but I did try by adding gas and
> spraying starter fluid.  No effect the engine still dies very quickly
> regardless of throttle position.
>
> Old gas-- this problem was replicated while the engine was on my run
> stand which has its own fuel tank to which I recently added fresh
> fuel.  So I sincerely doubt that old gas is an issue here.
>
> Carburetor base== one of the comments said that I should check the
> base of each carburetor to be sure they were flat I did and they are
> perfectly flat.
>
> Carburetor insulator and gaskets== I am using paper gaskets on both
> the top and bottom of the insulators.  The insulators and paper
> gaskets have been opened up to match the size of the carburetor.
>
> Throttle plate-- another comment suggested being sure the throttle
> plates are completely sealing the carburetor.  I checked and they are
> and there is no leaks from the throttle shaft on the base of the
> carburetor.  As a precaution many years ago I added the rubber O-ring
> kit on all the throttle shafts.
>
> Vacuum gauge-- it was impossible to get any kind of reading on a
> vacuum gauge because the engine dies so quickly.
>
> Bottom line to all this I am still absolutely baffled.  I'm very
> thankful for everyone who is weighed in on this problem.  I'm hoping
> against hope that it will be some simple thing.  The fact that these
> carburetors worked for years and then suddenly didn't work with
> absolutely nothing being done to them is completely baffling.  Again
> many thanks to all.
>
>
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