Originally Posted by kartectuning

Guys

I am running a stock evo 9 engine with the following mods

Kelford 272 mivec cams
Stock long block (stock head and valves, stock valve springs and retainers)
Rev limiter set at 8200 rpms
Gates timing belt
Stock balance shafts in place with belt
ARP rob bolts

Running a gtx 35 at 30 psis with an aquamist hsf3 and a twin nozzle setup on stock ecu for 2000 miles

Change to Aem series 2, ran 50 miles and one or two exhaust valves at cyl 4 got bent

Cylinder compression on all cylinders at 120 psis even, conservative tune.

I can understand the softer stock spring may have give in and causing valve float touching the piston, but in the subaru world with avcs valves tend to drop when the AEM series 1 variable valve system approach (cam sensor signal input basicly) was not well engineering causing erratic fluctuactions from sensor reading,

I would really like to hear of bent valves situations caused only by running stock springs that may tend to float, or rocker arm issues, I really do not want to hear that anyone had a similar issues running the aem series 2 even on stiffer springs, because that will really sad with a built engine...

Let me know if you have had a bent valve issue from valve float, on wich ecu please

Originally Posted by sobo

Have you ever been inside an evo 9 cylinder head?

Can guarantee you floated a valve into the piston. Kelford 272 are very aggressive cams with 11mm of lift. They are NOT designed for stock springs and retainers, and definitely are not designed for a higher rev limit than stock when using that particular spring set.

There is no tuning involved with the exhaust side cam on an evo 9 motor, only the intake. So unless you aligned the timing belt wrong, you had valve float.