[Terry Stapley]

A couple of weeks ago I posted a thread with a question about which size of carb is best for an emissions test. Big or Little.
My 750 Holley DP has been acting up and having just acquired a Quick Fuel Technologies 850 DP from Forum Member Brent Lykins, I thought I would give the 850 a go at passing the IM test. The 850 was cleaner than the 750 was at my last IM test in 2006.
I tried to have everything equal engine wise for both tests. Initial timing set at 8 degrees advance with the idle set at 1000 rpm. Both tests had new spark plugs, and both carbs had # 71 jets in the primaries and was adjusted for lowest readings.
Utah Standards for my year engine are the same at idle and 2500 RPM:

700 ppm HC
5.0 CO

Results: Year 2006 750 Holley

Idle - 639 ppm HC
4.92 CO

2500 RPM - 220 ppm HC
2.5 CO


Year 2008 850 Quick Fuel Tech

Idle - 252 ppm HC
4.81 CO

2500 RPM - 15 ppm HC
.28 CO

I am very pleased with the test results and even more pleased with the added performance the QFT 850 gives the engine. At 418 CI it seems to like the additional airflow because the 850 really makes a difference that I can feel in the "seat of the pants"!! It idles easily at 800 RPM and throttle response is instant!!