<VV> Appreciate some help with poor idle, stalling

Dennis Pleau dpleau at wavecable.com
Thu Feb 12 18:21:10 EST 2015


The key is what you said about putting your hand over the carb.  They should both suck the same amount.  You need to balance the carbs.  I don't know how to do it without a 'Unisync' (sp), but there is a procedure in the shop manual that will work.  Ifyou have access to a Unisync I cane post a procedure.

Dennis

-----Original Message-----
From: VirtualVairs [mailto:virtualvairs-bounces at corvair.org] On Behalf Of Bill H. via VirtualVairs
Sent: Wednesday, February 11, 2015 10:33 PM
To: virtualvairs at corvair.org
Subject: <VV> Appreciate some help with poor idle, stalling

                                                                 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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