[6pack] Mixture Adjustment

[John Cohen]

Thanks Dick,  You are exactly right, the manuals I looked at all say to lift
1/4".  I leaned out the needle in the front carb 1 turn, went for a 20 mile
drive, pulled a plug from the front carb and it was the classic tan color.  

John Cohen

-----Original Message-----
From: Sally or Dick Taylor [mailto:tr6taylor at webtv.net] 
Sent: Monday, June 25, 2012 2:22 AM
To: John Cohen; 6pack at autox.team.net
Subject: Re: [6pack] Mixture Adjustment

John---First off, the "lifting of the air valve" to determine the air/fuel
mix at idle can give a false reading, if one follows some of the manuals. If
you do try this test, the valve should only be raised about 1/16", not 1/4"
as some manuals state.
 To lean out the rich carb, screw the adjustment counter-clockwise about 3/4
of a full turn to start with. You can do this with the engine running, but
it may temporarily stumble in the process. (Doing so lowers the needle into
the jet.) Clean the three "rich-looking" plugs and go for a drive. Recheck
the plug coloring.
You may have to check the float level in the front carb, if leaning out the
a/f mix didn't help. 

Dick


-----Original Message-----
From: John Cohen
Sent: Sunday, June 24, 2012 9:07 AM
To: 6pack at autox.team.net
Subject: [6pack] Mixture Adjustment

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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