Gray86hatch

iTrader: (83)

Your problem may not be the springs. Really need to look at all the stuff you have first and make sure you don't have a PR rocker spring or tune up issue. If you want to just throw $$ away send it to me.

Tim

v8pwr

iTrader: (19)

You probably do not have enough spring or your springs need to be shimmed . You're running an aggressive lobe with a 1.8 rocker . They may be an error in your actual valve lift . If you have the lifters I think you have, the only thing holding back your setup is the spring . The right spring will easily give you 7500rpm capability . Your rockers are heavier than stock but they're adjustable which is necessary for the limited travel hydraulic roller lifters . If shimming your current springs doesn't help then look for more appropriate valve springs . PAC has a lot of new springs coming out . I would look @ the -1207 or -1209 and shim them . There are other quality springs out there as well . I think Morel recommends a max of 200 lbs seat pressure and 550lbs max open pressure for those lifters . They're designed for aggressive setups .

Marble_Sharp

iTrader: (5)

I think this may actually be the problem. A third party actually set-up the heads. They may be set too close to coil bind. I am going to ask the engine builder to get with MAST and ask them exactly what the springs should be shimmed at. The Heads, the springs, the retainers, and locks all came from MAST.

Marble_Sharp

iTrader: (5)

Can't run the stock rockers with these lifters... already tried that...

Marble_Sharp

iTrader: (5)

Again, heads were set-up by a 3rd party. I was told the pressures are -

Seat Pressure 193 +/- 5lbs

Open Pressure 460 +/- 8 lbs

I am thinking they may have just been set-up too close to coil bind. He was specific about if I ever changed the cam to any higher lift, they were very tight and would need to be re-shimmed.

miami993c297

iTrader: (6)

Been there, done that...spent a lot of money with incompetent persons!!!

The positive of your situation...you will identify who really knows about valve-train in this business...

BTW, valve-train instabilty was starting around 5800rpm with my ETP 245 and 2.10 intake valves, my engine is now running to 7500 like a breeze:



Christian

MxJxG

iTrader: (1)

hi, just want to drop my 2 cents. I have built alot of engines and I think there are only 3 things that cause valve float. 1*springs* either improperly set up or springs are too weak for the application. Or 2*push rod length* I have seen a ton of people change to aftermarket heads and not check push rod length causing improper valve train geometry. 3 *lifters* I have seen lifters bleed off oil pressure at high RPM causing valve float. Usually on roller lifters a tell tale sign of this is flat spots on the rollers from the lifter "hopping" up & down during lifter bleed down. Hope you get some answers. Please let us know when you get it figured out.

AES Racing

iTrader: (6)

If its ever a question, best to double check and confirm, independently.

What i've seen with these heads, that standard valve sets up at 1.760" with .060" spring locator.
So provided you have a spring that binds at 1.050", you have exactly .660 available lift, no shims.

That combination needs a spring that is 500lbs/in

Marble_Sharp

iTrader: (5)

What was the solution to your valve-train instability?

miami993c297

iTrader: (6)

-1) Get rid of the YT Ultralite and went back to OEM Rockers

-2) Went to Xcledyne Titanium coated valves:





And then went back from PAC 1521 to PSI LS 1512 ML..........as in the video.

Christian

Marble_Sharp

iTrader: (5)

Here is an update - it appears the Heads were set-up incorrectly causing coil bind! Put in a new set of springs, correctly, and problem appears to be solved. SHould be back up on dyno within the week, possibly even today!

Wnts2Go10O

iTrader: (12)

i knew there was more to it that just valve float. valve float from the rockers is almost always a dipin the top rpm not a complete drop off