<VV> 64 turbo acceleration issues

[Harry Yarnell]

Your voltage measurements at the coil MAY be ok; it's your troubleshooting
that's flawed.
You're not taking dwell into account. You don't have a steady state voltage
there.


-----Original Message-----
From: virtualvairs-bounces at corvair.org
[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Kurt Guttensohn
Sent: Monday, November 14, 2011 8:36 AM
To: virtualvairs at corvair.org
Subject: Re: <VV> 64 turbo acceleration issues

Well, 
I tried a few things this weekend.  Checked the adjustments on the carb, and
all were right on the recommended settings.
So I swapped out the Pertronix with one from another car.  This seems to
have gotten rid of the stutter when I really accelerating.  
I drove for about 40 min, so the car should have been plenty warm.  I think
I will try one more test of putting the old one back on and getting it to
stutter,
then switching to the new one and making sure it does not do it.
It is still dribbling gas after I shut it down.  That I think I can live
with for a while.  I checked the return line and it id functioning properly.
 So I may try the all metal fuel inlet valve from a Corvair vendor.
With all the emails on the resistance wire, I did check the voltage at the
coil (before I replaced the Pertronix).  It was 7.4, until I pushed the
throttle.  Then it would climb to 9.8.
So, I rigged up a a voltmeter and watched it while I was getting the
stumble.  The voltage was between 8 and 9 at that point. 
I don't know why I keep saying I am using the Pertronix.  They are both
Crane FireBall ignition modules. 
Thanks for all the suggestions and help.


________________________________
From: "Duane, Jim E." <JDuane at advprograms.com>
To: Frank DuVal <corvairduval at cox.net>; "virtualvairs at corvair.org"
<virtualvairs at corvair.org>
Sent: Thursday, November 10, 2011 7:56 AM
Subject: Re: <VV> 64 turbo acceleration issues

Hi all.

Hi Frank.  

    What sometimes happens is that while idling, the bowl overflow is sucked
in and masked from view by the closed throttle plate.  When you shut off the
engine and then look, the overfilled bowl spill can be seen.  I can't tell
you how many hours I spent on this!  Even to this day, with a pressure
regulator set to 4 lbs, after idling for a minute or so, my exhaust starts
to smell "rich".
    And this thread is still about stalling under full throttle!  Don't you
just love a mystery? (Humor!) 

    Jim Duane
    '66 180 CVT
    Colonial Corvairs
    CORSA 

-----Original Message-----
From: virtualvairs-bounces at corvair.org
[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Frank DuVal
Sent: Wednesday, November 09, 2011 8:43 PM
To: virtualvairs at corvair.org
Subject: Re: <VV> 64 turbo acceleration issues

I have no idea why a regulator would help gas dribbling after shutoff. 
Since when would gas pressure be higher with the engine off? It should 
be the same, as gasoline pressure is developed only by the spring in the 
fuel pump, not the stroke. Many people can not grasp this concept...

If you are thinking the heat of the shut off engine is raising the 
pressure, then what is the regulator going to do? It can only limit the 
flow of gasoline from the fuel pump into the gas line between the 
regulator and the needle/seat/carb inlet. If the engine is shut off, no 
gas flows. Therefore no regulation.

It's not like the regulator spits out the excess pressure through a vent 
hole. That would be exciting!

The return line system used on turbos and late late production adds 
another wrinkle to the normal system described above. The return line 
VENTS the gas line from the fuel pump to the carb/needle/seat. So, when 
you shut off a normally plumbed turbo, the gas line pressure between the 
fuel pump and carb drops to ZERO. So what will a regulator do? Nothing.....

Unless you plumb the regulator between the fuel filter and the carb, in 
which case the line before the carb might not vent through the return 
line, thus causing a problem, not fix one.

So, if the fuel line pressure drops to zero (make sure the return line 
is clear back to the tank) and gas still drips in the carb, the fuel 
level in the carb is where I would start troubleshooting.

If the accelerator pump has a hole in it, the symptom will be rich 
mixture at idle. Then as the hole gets bigger, rich at speed too.

Comments, Smitty?

Frank DuVal

Flame suit on, as we are playing with gasoline here!

On 11/9/2011 8:48 AM, Kurt Guttensohn wrote:
> Ok,  Thanks for everyones input so far.  Here is what I am going to try:
>
> For the dribbling gas after shutoff
> 1.  install a fuel pressure regulator and gauge.  I will probably have to
order one.  Anybody have suggestions.
> I had a cheap'o regulator on there that I removed because the car wouldn't
start with it on and wide open any more.
> - I do have a return line, that seems to be functioning well.
>
> For the stumbling during acceleration
> 1.  Try replacing the Pertronix setup with a spare setup I have.
> 2.  If that does not work, I will dig up the old points and condensor and
try that.
> 3.  Check the accelerator pump.  Only about 1 year old, but it could still
be an issue.
>
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