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Discussion Starter · #1 ·
My Shelby clone is running a 715 Lemans Carb. After a year of tuning, the engine idles smooth as silk at 750 RPM, pulls hard with no flat spots and starts the second you hit the key. The only issue is left is that I am still running rich with black soot on the plugs and out the exhaust. The primary jets are stock 68s with 78s in the rear. Should I try 66s in the primary side or just leave well enough alone?
 

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are you getting the sooty plugs at

1) wide open throttle & accelerating,

or

2) at cruising speed with the throttle barely cracked open & low RPM ?

if the latter, you might be able to get results by just adjusting the low speeds screws.

Z. Ray
 

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Discussion Starter · #3 ·
The soot happens at idle. It doesn't foul the plugs. I changed power valves a couple of times to see if that was the problem. I'm pulling about 12 pounds of vacuum at idle. The PV is an 85 and I can feel it kick in at just the right time. The idle screws work best at about 1/2 turn out. I know that's a bit tight, but that's where I get my best idle quality.
 

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Discussion Starter · #5 ·
302, 351W Heads, 10 to 1 comp, stock Ford solid lifter HiPo cam, Blue Thunder Cobra intake, Holley Lemans 715 with a 1" spacer, Tri-Y headers.
 
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