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RE: Choke conversion

To: spitfires@autox.team.net
Subject: RE: Choke conversion
From: "Dummer, Dan" <Dan.Dummer@BestBuy.Com>
Date: Fri, 21 Jul 2000 14:23:04 -0500
I'll try to summarize my responses for far.

Gas is getting to the carb.  The gas filter (new) and fuel pump (also new,
electric), and fuel regulator (new, set to 2) are working as designed.   I
can disconnect the fuel line from the carb, and see that fuel is getting to
the carb smoothly.

Timing, while not set right (because I can't get it running), is as close as
I can get it.  And the plug wires are in the right sequence.   I have
verified this by aligning the timing mark to TDC, and then pulling the top
off the dizzy, and verifying that the rotor was at #1.  Actually it was just
before #1, which seems right since the engine was at rest.  Once I
determined that #1 was right, the rest of the plug wires fall into place
easily (1,2,4,3) going clockwise from #1. (don't quote me on that, I'm not
looking at the machine right now).

EGR valve.   Since I'm running a header and there isn't a place for it.  So
I have plugged the hole in the intake manifold with a brass fitting.  I have
visually verified that the brass fitting is not impeding the airflow, in as
much as I can't see it in the throat of the manifold when the carb is off.

Vacuum line(s).  Since there isn't an EGR valve, there is only one vacuum
line.  Carb to vacuum advance unit.  

Fuel level in the bowl.   I think its right.  There is fuel in the bowl (its
full each time I pull it off).  I replaced the float valve, and adjusted the
height of the float per specs.  I will try to pull the damper piston tonight
and see if I can see down the main jet to determine if I can verify the gas
level in the bowl visually (Thanks Doug).  

Ramble mode on:

Some one correct me on this though.  At idle, I am pulling gas through the
idle jet, not from the main jet (hence the name idle jet).  Or am I pulling
fuel from both jets ?  Shouldn't I, in theory, be able to get the car to
start and idle from the idle jet alone ?   Thats the part that really
confuses me.   To get a car to fire, and idle (albeit poorly), I just need
enough vacuum created to pull gas through the idle jet, and mix it with the
appropriate amount of air.   The amount of air that reaches the engine at
idle should be determined by 3 things.  1) Position of the butterfly.  Which
is almost closed at idle.  This is set by the idle screw on the throttle
assembly, one and a half turns up from completely closed, per the Haynes
manual.  2)  The air mixture screw on the forward side of the carb (large
yellow nylon bolt, with a brass insert for fine tuning).  I can't get this
set until the car runs on something other than starter fluid.  I'm not sure
what the initial setting should be (chime in if you know, Haynes said don't
touch it) but, I've tried just about every setting so far.  And finally. 3)
The choke.  Which is as I understand it, a true choke instead of an
enrichment circuit.  Which means it is shunting the air flow and therefore
making the mixture richer.  Shunting the airflow also makes the vacuum
greater over the idle jet causing even more fuel to be let into the system.
It really is such a simple process... I am ready to tear out what hair I
have left in frustration. Arg..

Ramble mode off:

Thanks all,
Dan

> -----Original Message-----
> From: Dave Chu [SMTP:dave@ece.concordia.ca]
> Sent: Friday, July 21, 2000 11:49 AM
> To:   Dummer, Dan
> Cc:   spitfires@autox.team.net
> Subject:      Re: Choke conversion 
> 
> 
> 
> In message
> <F74E89C7EA1DD31186E900805FA7993005205C38@cs02mail.bestbuy.com>you w
> rite:
> >
> >magical answer... yes you....)   Which brings me back around to my
> original
> >question, can I ditch the water choke (which I don't trust) with a
> >mechanical choke ?
> >
> 
>  Hi Dan, it sounds like you are not getting gas to the engine.  Have
>  you make sure the gas filter and pump is working?  Check the bowl to see
>  if you have gas in it.  If the choke is not functioning it will cause the
>  car to run rich or flooding the engine.  You should get a strong gas
> smell
>  if the choke is not working properly.
> 
>  The water choke is a source of problem for many late model spits.  I use
>  to have the same problem on my car running too rich because the water
> choke
>  not working and it did not matter how much I adjust the needle.  Instead
>  of buying a custom choke conversion kit for the ZS you can try an
> universal
>  kit from your local parts shope.  JC Whitney sell them for about $6.00,
> the
>  part number is 83KP0840R.
> 
>  The universal kit does not fit the ZS exactly, you will have to do some
>  filing of the cover that comes with it.  It should take you a couple of
>  hours to install the kit.  After I stalled the kit my car ran much better
>  and with the correct mixture.  Good luck.
> 
> Dave                                                  |\ |     | |      
> _______________________________________/\  /\  /\_____| \|_____|
> |____________
> Dave Chu                                 \/  \/       | /|     | |  
> Dept. of Elec. & Comp. Eng.                           |/ |     | |      
> Concordia University              Voice:(514)848-3115   Fax:(514)848-2802 
> 1455 de Maisonneuve W. H961       Email:dave@ece.concordia.ca
> Montreal, Quebec, Canada H3G 1M8
> http://www.ece.concordia.ca/~dave/addr.html
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ~~~~
> 

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