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M4mE California emmissions Chevy 350 Chevy c20

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Cfrench192:
So I have a 6000 lbs truck. When I put in better gas, the problems go away.  My camshaft has 250 degrees duration at 6 degrees .  I fail smog for hi nox.  (Double the limit). New cat.  3 inch single exhaust.  Lots of air flow.  How can I modify my carb.  Holley rebuilt m4me.  I believe 71 jets with 51 m metering rods.  It has a cruise/ off idle stumble when I'm cruising around 15-25 mph.  On the freeway, if I floor it.  All I hear is a bag of marbles.  Please help.  It has an electric edelbrock 120 gph fuel pump.  The air fuel gauge almost always reads 17.2.  Around town and on the free way.  The timing is happy usually around 2-4 btdc initial and 91 octane. This is all with the a.i.r. Pump functioning .  Is there anything I can modify or should I try to modify.  (Idle channel restriction???)

Jeffs68:
EGR valve working? Ports clear?

Cfrench192:
Yes.  It's a universal egr with no restrictions ( no orfices). The motor has swirl port heads and runs great.  It seems like the camshaft requires more fuel.  At cruising / part throttle. 

Jeffs68:
What are the other emissions readings; HC and CO.

Also, how have you verified the EGR is working; ie...applied vacuum to valve to stall or stumble engine?

Cfrench192:
Vacuum pump on egr stalls engine.  Hydro carbons 31 ppm at 15 mph and 21 ppm at 25 mph.  Co % is 0.00 for both speeds.  Nox is at 3292 at 15 mph and 1996 at 25 mph.  Co2 % 11.1 and 10.6.  %o2 is 4.9 and 5.5

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