<VV> Re: main jet vs idle

[Roger Gault]

Is it possible that the fuel pump is weak (leaky valves?) and isn't pumping
at low RPM.   Engine goes lean.  Rev it up and refill carbs...
Seems really unlikely - maybe impossible.

Roger

----- Original Message ----- 
From: "Padgett" <pp2 at 6007.us>
To: "Larry Forman" <Larry at Forman.net>; <virtualvairs at corvair.org>
Sent: Saturday, November 19, 2005 10:23 PM
Subject: Re: <VV> Re: main jet vs idle


>
> >   As for the #4 plug intermittently not firing, REPLACE it!  Splurge the
> > $0.99 for a spare plug.  LOL.  It is very conceivable that you might
have
> > a marginal plug.
>
> Well the good feeling was shortlived. Am almost beginning to think that
> there is something else going on.
>
> Replaced the odd #4 with a good spare and am now able to identify some
> really odd things going on.
> First, it revs nicely but at steady 2000 rpm can feel just a bit of a
> flutter in the exhaust, not a lot more like twice a second.
>
> Second it starts out with a nice 650 rpm idle in D but the longer it runs
> the more often and quicker it just drops to 400 rpm. Smooths out if I open
> the throttle just a bit and then returns to smooth 650 rpm. Idle in N is
> steady at 800 rpm.
>
> Have checked timing often and is rock steady at 14 degrees below 900 rpm.
>
> Pulling plug wires at 800 rpm in N produces a similar minor (under 100
rpm)
> drop from each cyl. Think I really have it well balanced.
>
> When it drops to 400 rpm the engine seems relatively smooth but can pull
#3
> and #4 plug (center cyls) wires with no apparent effect.  When #1, #2, or
> #5 are pulled engine stalls. Pull #6 and engine seems to run a little
> better for just a second as if #4 were firing again. Does same when
> reattached. Verified plug wires are in right order.
>
> Have had ignition analyzer in parade mode and is no apparent difference
> between when at 650 rpm and at 400 rpm. But am not entirely sure what I am
> looking at. Assume the bright spot in the spike is where the plug fires.
>
> Right now valves are adjusted while warm running to 1/4 turn from clack.
Is
> there any chance this is not enough ? Now that I have separated the bad
> idler noise engine is pretty quiet while running. When covers were off was
> evident the engine is pretty clean with no sludge apparent.
>
> Know the engine is somewhat worn, is some blowby evident and appears to be
> using some oil though excess idling may be a factor. Suspect it is a
74,000
> mile original but compression on all cyl is above 150.
>
> Have learned that just taking apart to see is really not a good idea, at
> least not while the vehicle is still mobile so want to exhaust all
> possibilities before pulling more than the valve covers.
>
> Thanks for listening,
>
> Padgett
>
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