<VV> Appreciate some help with poor idle, stalling

MarK Durham 62vair at gmail.com
Thu Feb 12 13:08:52 EST 2015


Bill, we don't like to see compression spreads any more than 20 psi apart,
but, putting that aside because thre is nothing you can do about it accept
for trying to adjust valves, it may make the engine a little rougher, but
they usually run OK down into the 100's.

I would suggest you pull the tops of the carbs and the idle circuit cluster
out of the middle of each and make sure everything is clean.

When I see that turning the idle mixture screw does nothing, it usually
means there is no idle fuel flow, and the carb is adjusted to compensate.
Case in point, you got good suction on one, which is probably OK, and none
on the other, when you put your palm over the top of each.



Mark Durham
Hauser, Idaho
62 Monza coupe Red/Red 4 speed

On Wed, Feb 11, 2015 at 10:32 PM, Bill H. via VirtualVairs <
virtualvairs at corvair.org> wrote:

>                                                                  B"H
> Hi all:  I'm still having awful problems with my Monza when idling,
> especially in Drive, where the idle is unsteady, rough, and the engine
> frequently stalls unless I put her in Neutral.  She's a 66 Monza, 110, PG
> with factory A/C.  The idle tends to be uneven, sometimes she'll surge,
> then slow down.
> So far, here's what I've done:
> 1.  New plugs, NGK, gapped to .0302.  Carbs, rebuilt 2012 by Grant
> Young3.  Fuel pressure, 3-5 lb to both carbs (best as I can determine,
> gauge crapped out on me).  Stock fuel pump used, brand new.  Both carbs
> getting gas from fuel lines.4.  Fuel tank drained, refilled with fresh gas,
> drygas and octane booster.  Saved a bit of old gas in a jar, no water or
> impurities found5.  Compression test:  Engine warm, throttle at WOT per
> gauge instructions (all plugs out, coil wire grounded):
>     #1 - 133    #2 - 129    #3 - 155    #4 - 135    #5 - 121    #6 - 130
> Cylinder #3 is a bit high, and #5 is a bit low.  However all are with I
> think within acceptable range.
> 6.  At idle, in Neutral, when I put my hand over the throat of the left
> carb, the suction is STRONG and the engine falters and stalls if I keep my
> hand there.  Turning the idle mixture screw does have a minor affect on the
> idle.
> 7.  With my hand over the right carb, the suction is WEAK and the engine
> actually smooths out and the idle speed increases.  Turning the idle
> mixture screw all the way in or out does nothing to change the idle.
> 8.  Removed both idle mixture screws, sprayed carb cleaner in the port,
> replaced screws.  Tried revving the engine with my hand tightly over each
> carb throat separately, with the hope that the surge of fuel might wash
> dirt or debris from the idle circuit.  Didn't change idle at all.
> 9.  Carbs are tight, both on the intake manifold, and the air horns are
> tightly screwed to the carbs.
> 10. Plug wires are in good shape, engine has Pertronix ignition system.
> 11.  Observed small amount of fuel dripping from venturi cluster of each
> carb.  Clark's tech said this is normal as long as it's coming from the
> venturi cluster and it's only a small amount.
>
> I do appreciate your help guys, if anyone can think of what could be
> wrong.  As I might have mentioned already, I depend on this car for daily
> transportation and it's not really driveable in slow, city traffic
> (although on acceleration she seems to run OK).
> Thank you!...Bill Hershkowitz
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