[RallySnake]

I have spent a lot of time tuning Holley Carbs. The most recent one is an Avenger 670. It is SO much easier with an A/F Ratio meter. My primary goal was to get rid of the hesitation as I started up from a standstill. This is the avenger's biggest fault. I am also trying to keep the plugs clean longer and cut down the unburnt gasoline blowing out of the sidepipes at idle that make you smell exactly like exhaust fumes. The third goal was to improve the gas mileage for the long distance rallies that we run. What I have learned from much reading on the internet is that you want 14.7 (parts air) to 1 (part gas) in idle and low load (cruising) situations. You want 12.5 to 1 in full throttle acceleration. And, it does not matter if the ratio goes as high as 15 or 16 to 1 in throttle off, deceleration.

I started with the jets. I reduced the sizes of the two jets in the primary side (front bowl) several times until I got close to 14.7 at steady 50 mph cruise (3rd gear). Then, I concentrated on swapping the rear jets until I got 12.5 under full throttle (testing this is dangerous)! Next, I swapped the plastic cams until I found that a blue one on the primary side would get rid of most of the delay leaving the line. However, it ran out of juice just before the vacuum secondary kicked in. So, I changed the spring to the yellow one and that helped the secondary kick in faster. Then, I reduced the squirter size in the primary to make it last longer. Now, there is hardly any delay in the changeover. The car runs about 250 miles on a 22 gallon tank of gas on fairly fast rally legs. It does a lot better cruising on the freeway. The plugs stay very clean.

You can get the jets and cam sets very quickly on Summit Racing's website and you can buy individual items like the squirters on eBay really cheap (but it usually takes much longer).

RS