Those numbers aren't bad. Do you have before and after numbers? Since there's such variability in flow benches, comparing before and after numbers from the same bench will tell you more about what was done.

 

Hi Shreveport. I think his bench flows 215 intake on stock heads. Not the 5xx casting though. Maybe he will chime in on this one.

Jeff D.

 

The stock LT1's flow "about 212-215 on the intake and 145-150 on exhaust. Some exhaust ports have some pretty bad bumps on the shortides and flow slightly worse but the #'s are always "close" to this.

If the heads are dirty and have carbon on the valves and around seats, they might flow less than 210/145 depending on how bad" they are.

The 516's flow about 225/155. There again, the #'s vary because of conditio of valve job and cleanliness of the ports but these #'s are what a 561 flows in "descent" condition.

The flow #'s on the ported heads will vary a lil depending on what valve is used as well.

1-Ferrea
2-REV
3-Manley

These are the most common valves that I work with and they are in this order in price and CFM. Most expensive and best flowing being the Ferrea.

NightTrain66