Valve float or no? Dyno graph and vid inside...

[1badz]

Put the car on a mustang dyno last week and was overall happy with the results. During the pulls though the car sounded like it was hesitating/breaking up a bit then went away. In the video you can hear it from 00:32 - 00:34. Attached is the graph as well. I lose about 100whp from about 5100-6100.
The guy at the dyno suggested it could be a fuel issue or timing. I WAS pulling 10* via the digital 6 and it has a brand new 255lph pump and hotwire kit. The valve springs are questionable, definitely have some years on them. Any suggestions/ideas would be greatly appreciated. Thanks!






Setup consists of:

-unknown baby cam (was told hotcam)
-dart pro1 heads (as-cast/unported)
-150 wet shot
-th350 with 3700 stall nitrous converter

[quik95lt1]

was that on the shot??? in the 4krpm range it looks like detonation with the little wobbles and spikes........the drop off after that seems like a bigger issue than valvesprings.....but id check them anyway........the car sounded horrible on the dyno....the operator was NOT smart for keeping his foot in it through that

[Z28pr0jekt]

The :32-:33 second mark is where it sounds like it's floating to me but it just didn't sound good altogether, sounded like a big load on the car and something not quite right.

FYI before my turbo build my car seemed to be hitting what seemed like a limiter around 6000 rpms under load. (Limiter was set to 7000, in neutral it would free rev fine)

Come to find out the shop that originally installed my springs, installed them at the wrong height. It sounded like the :32-:33 second mark except my car didn't break through it.