I went back and read an old thread from Jim Laroy on FBBO. He tested something similar. His torque and power numbers were down quite a bit from what EM had stock. Jim used the smaller Summit cam (6400) and with headers and a 750 carb Jim had 432 ft lbs @ 2500 RPM and 297 HP @ 4300 RPM. Maybe it was because Jim used step headers. Jim if you're reading this did you have accessories on that engine?
With the 509 cam and M1 intake Jim made a similar HP number (387) at 4900 RPM. I guess 4900 RPM might just be where the stock heads finally choke you out no matter where you put the IVC.
https://www.forabodiesonly.com/mopar/threads/dyno-testing-a-stock-1972-440.249866/page-2 No accessories just running the electric water pump. We had no time for tuning as all the changes had to be made in one day with an audience watching and guessing what horsepower and torque each change would make. The fun swap was the last one when we went from the stock 906 heads to the mildly ported 516 heads (250 cfm @ .500") and the horsepower jumped all the way from 387 to 449.
We did something similar with a sub 10:1 440 making 404 HP and 483 TQ and took it to 658 HP and 552 TQ.
Thanks for clarifying Jim. I seem to remember some naysayers suggesting you must have had a friendly dyno with some of the results you had with other setups - I was thinking it sounds like the dyno wasn't that friendly. The head swap was big for sure, I really liked that thread!
Was there a write up on the 404 HP to 658 HP testing?
