<VV> 110 PG with rough idle and wanting to stall at stops

[Tony Underwood]

At 11:49 PM 9/19/2009, Stephen Upham wrote:
>I developed a problem during a club out of town activity last
>weekend.  The Monza ran fine on the way down at highway speeds and
>after arriving, at town speeds.  I parked it on the town square for
>the show.  After the show was over it started and ran fine for about
>a mile and a half.  Then it started to experience a rough idle and
>wanted to die in drive.  I ran ok in neutral but I sensed that it
>wasn't 100%.  I was able to drive it back to Dallas without too much
>hassle except for the time I stopped for gas to check for leakage on
>the new oil pressure sensor/sender.  The old one began leaking, and I
>and some members had to replace it in the parking lot of the hotel.
>Fortunately, it wasn't raining at the time as it had been pretty much
>all day.  I drove back to Dallas in the rain which was moderate until
>the last fifty miles which were torrential.  I got a damp carpet on
>the driver's side from the high beam switch to the seat.  I
>disconnected the battery when I got home and fan dried the interior
>for two days.  Well, today I started it up again.  It took several
>tries to get it started.  After it warmed up, I checked the advance
>and it is where I have had it for the last five months at 24 BTDC.  I
>checked the rpm at idle and got about 900, fast, I know, but remember
>that it was dying in drive at stops, so a club member stepped up the
>idle.  In drive, the rpm drops to 600 and it begins to run very rough
>and the engine is vibrating to the stroke of the pistons.  It kept
>running, but again, very rough.  Almost everything on the engine that
>involves fuel or spark is less than seven thousand miles old and the
>carbs are about 500 miles old (fresh complete rebuilds).   It has a
>Petronix ignition.  One of the club members suggested the PCV may be
>loose (it is the kind of hose configuration found on the A/C cars),
>another suggested it might be water in the gas from a bad fill up,
>and the other club members were scratching their heads.  I need some
>advise as to what to check next.  I did think tonight to check the
>carbs for leaking venturi which I will do in the morning, and then
>maybe pull the plugs and see if there is anything I can glean from
>them.   What else should I look for?



Dirt inside the carbs.

I know, recent rebuilds, but what's inside the tank?    Those stone 
filters only stop the big stuff and even then they don't work that well.


I've gotten into the habit of putting an additional fuel filter on 
every Vair here to keep dirt out of the carbs.   You might try, just 
for funzies, unscrewing the idle mixture screws and blasting some 
high quality (not that Advance store house brand stuff) through the 
mixture screw holes and see if it temporarily cures your 
problems.    If it does, pop the tops off the carbs and look for silt 
in the bottoms.


Been there done that, it's why the 'Vairs here all have extra 
filters.   I use those nifty glass filers that screw together and are 
"cleanable", and yes they ARE touch and won't break, thick glass, and 
they don't leak either.   Got one that's been on the '67 coupe for 6 
years now, emptied it out about 4 times so far to clean out 
debris.   Another on my '60 is doing ok so far with only 2 cleanings 
since the engine went back into the car a year anna half ago.   The 
'65 ragtop has a metal filter on it that's not cleanable but will get 
one sooner or later.   Me, I cut a piece out of the steel line 
feeding the fuel pump so I can see inside the filter easily to check 
for crud.    Wanna remain stock in appearance, add the filter where 
the rubber hose joins the engine bay fuel line to the feed line from 
the tunnel, behind the wheel well on the driver side.



tony..