Test #1: BASELINE FLOW TEST BEFORE MODIFICATION The stock heads, as delivered, were nearly within 10 cfm at all measureable lifts. At .400" lift on-up, the heads are always within 6 cfm of advertised flow data.

TEST#1 EXHAUST BASELINE flow test

Test # 5: EXH. MOD#3 SQUARE UP THE "D" PORT & SLIGHT RECONTOUR UNDER VALVE SEAT (per test 4). Air Flow Research recommended making this change and it shows significant improvement at all valve lifts. However, some low lift flow improvement might be attributed to my recontour just under the valve seat. I removed a little more material (.025" or so). This will be my final change to the exhaust port. I've exceeded advertised "street-port" flow numbers at .400" on-up. Low lift is nearly the same as advertised flow numbers.

Test # 6: INTAKE MOD #2: RECONTOUR VALVE GUIDE, CLEAN UP AROUND VALVE SEAT. I noted that the intake vale seat was recessed into the combustion chamber, leaving a small "step". I used a 1/8 inch sanding roll to grind off the step, leaving a smooth transition from the top of the valve seat into the combustion chamber. I also found a tiny sharp edge inside the valve seat, where the seat meets the aluminum. A few seconds with a sanding roll and it was gone. In addition, I removed the three prominent ridges that are figments of the CNC program. Interesting airflow improvements resulted across all lifts. Low-lift flow improved considerably. High lift improved by a percent or two. Mid-lift (0.2 through 0.5 inches) still needs some help. Could the short side radius need attention? We'll give the intake port another modification & flow test before applying what we learned to the remaining ports in the cylinder heads.