First, I think that is a great engine for it's purpose and any comments are just bench racing/bs-ing
On the TFS heads, I generally end up with about .015-.030 shim and some swapping of springs to get everything where I like them. That's 7-14 lbs of seat/open pressure at most, not counting spring variance, so not sure it changes much, but w e always do it.
Additionally, I think you may just have ran out of cam, using similar grinds, but 30 cid less, we ran the peak off the edge of the graph. I also tend to run that type of lobe a little later, but again, nothing incredible. I typically put them at 108 on a high vacuum street stroker, so tiny amounts
I can't help but think that it could be a glitch or loading function of that style dyno. However, your airflow measuring seems to show that it did do something different.
It beats me, but I did throw some curves below to show we aren't seeing that drop with TFS heads or Morel standard travel lifters and good lobes.
Also, as you know, it's nearly impossible to compare these builds, especially across at least three dynos but:
- 1st one is a TW, iron heads, and it ran up pretty well with standard travel lifters, 241-ish intake lobe but iron heads, same spring pressures as I do on TFS.
- Second one is short travel lifters, but stock TFS with more spring, similar cam on 433 cid
- Last one is the mildest of the bunch but has both stock TFS and standard travel, with a cam with the same major intensity, unfortunately we didn't run that one out the back as far, but it was still doing well up top, although there is a little bobble at 6000
Those three though show decent curves past 6000 with std lifters, std head, then both combined, so it's odd the dramatic drop off you see
I have two going on the Stuska pump this week, neither TFS, but one is 482 inches, 330 cfm heads, a medium riser dual quad and a similar cam, but the next one next month will likely be on a local Superflow. The third is nowhere near the level of engine you just built, but I'll see what I can find on all three to evaluate Morels a bit more closely
I will say, it is a good thing when we are bantering reasons why a 6000 rpm FE is "only" making 580 HP with mostly off the shelf parts!