[6pack] Mixture Adjustment

[Bud Rolofson]

John,

I wouldn't mess with the needles yet. It could be that you could have  
too much gas pressure at the carbs especially the front carb.

Get a vacuum gage and fit a T-connector into your gas line right  
before it enters the carbs. It should run right around 1-2 psi. My car  
likes 1.5 psi. It didn't like 3-4 psi which is the reading I got  
initially so I put a pressure regulator/filter on and set the pressure  
at 1.5 psi and its run better ever since.

Your symptoms, no choke needed, stumble/stall, black plugs all  
indicate a too much fuel problem whether its pressure, stuck float  
valve, or something else in that front carb. Also the front carb is  
first in line to the gas line so my guess is that it gets a little  
more of the brunt of the pressure and is prone to the issues you  
described. The front carb fuel chamber on my car always has the most  
crud in when I clean it out too. I've become a believer in controlling  
gas pressure to ZS carbs and to cleaning out the fuel chambers as a  
regular maintenance task. It makes my life easier in the long run.


Bud Rolofson

71TR6 CC57365 (Good 6)
66TR4A CTC57806 (The Wreck-Almost parts)
66TR4A CTC57529 (The Project)
71F-250 Camper Special (Triumph Support Vehicle)
Z-50A Hardly Davidson 1977 Honda Mini-Trail Bike (Triumph Pit Bike)
levilevi at comcast.net




On Jun 24, 2012, at 10:07 AM, John Cohen wrote:

> Hi Guys,
>
> I had my ZS carbs rebuilt from Paltech, put everything back together  
> and
> find the front 3 cylinders way too rich and the rear slightly lean.   
> This is
> for a 1976 TR6 with stock everything and all emissions items still  
> present,
> Pertronix, Lucas Sport coil and Champion  N12YC's gapped to .035. .   
> The car
> starts immediately with little or no choke and seems to idle great  
> at about
> 900 PM, as it should.  When I lift the air valves on both carbs, the  
> engine
> stumbles and nearly stalls.  That should indicate a lean condition  
> on both
> carbs but I just do not see this on the front carb which appears to  
> be too
> rich by the look of the plugs.  The mixture came back from Paltech   
> adjusted
> to 1.5 turns CCW (down) from full rich position (fully up).  This is  
> 1/2 of
> the adjustment range.  My question is: To lean out the front carb,  
> do I use
> the adjustment tool clockwise or counterclockwise? My intuition is  
> to screw
> clockwise down to lean but from what limited info I can find on the  
> net, it
> would appear the opposite is true.  Am I on the correct trail here  
> or should
> I be looking for something else going on?
>
>
>
> John Cohen
>
> Rutland, VT
>
> 1976 TR6
>
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>
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