13 On the previous dyno test of the TTI exhaust, air/fuel (A/F) ratio was an ideal 12.8 to 12.9 after swapping the heads, the first two pulls showed the engine to be a litter rich with an A/F of 12.0 to 12.2. Next, the jets were stopped down to sizes on the secondary side. The brought the A/F back to an ideal 12.9 average during the pull, while rewarding us with 4 rwhp.
Upgrading to the new heads netted this mild 440 a gain of 51 rwhp. That’s a substantial power gain, when considering the mild cam grind (.447-inch) that does not support airflow compared to today’s modern cams with more valve lift (.500-inch plus) for the same duration to take advantage of the higher-flowing heads.