smokinz

iTrader: (2)

I've been searching a lot about FI and valve float issues(or at least similar dyno sheet as mine). Well i didn't really find anyone who posted how they fixed it or if it was even valve float.
here is a dyno sheet so you can chime in with your .02 on my problem.





Some specs on my build are- forged 383, 9.8-1 compression, cleaned up stock heads with patriot duals, rear mount tc-78 @ 7lbs.

So any way if you experienced similar results on the dyno, how did you fix it, and does that look loke valve float?

Squirts11

iTrader: (14)

Are your springs shimmed to within .050 of coil bind?

smokinz

iTrader: (2)

No they aren't, i am waiting for a shim kit from Summit Racing! Do you think that would be the most likely cause of my problem?

Squirts11

iTrader: (14)

In addition to having springs rated above the max valve lift, ensuring spring height (for max lift) is approximately .050 of coil bind (via shims) is ideal.

Shawn @ VA Speed

iTrader: (3)

what's the cam specs-you really shouldn't be having issues at 7psi

ou812/z28

i had a problem of the car once it made 12lbs of boost. the car would have a flutter sound and loose power and be flat.i changed coils,wires,plugs, and plug gap, also went to big stuff three and no change. then i checked valve springs that a local shop set up and said they where ok and would hande the boost. well just for the hell of it i removed one intake and one exhuast spring. checked the install hight and then seat pressure as well as full open. way to low on both. shimmed the springs but put them at .090 from coil bind.. went and ran it after that and the flutter was gone. so if it flutters then check your springs.

smokinz

iTrader: (2)

It is the XFI 280- valve lift 0.576 intake .57 exhaust, duration @ .050 is 230 I and 236 E, the springs are good to .650 lift and as i said before they are not shimmed yet, but will be hopefully today.

Dean95z28

iTrader: (7)

I think I am having the same issue in my car above 10psi. I guess I need to check mine as well. I am running patriot gold springs with a Zo6 cam.

HUNTER02SS

iTrader: (24)

Just because your springs are good for a certain amount of lift dosn't mean they are good for a FI setup.A boosted setup takes more seat pressure than a standard N/A Spring. The op is correct though. I wouldn't think you would see any problems at 7psi.

ss.slp.ls1

iTrader: (36)

Do you have Patriot Golds (135 closed/375 open) or Patriot Extremes (155 closed/410 open)?

smokinz

iTrader: (2)

I have these- Patriot Golds (135 closed/375 open)

MIGHTYMOUSE

iTrader: (59)

last time mine did that i had acidentally very low timing under boost.

MaxxMitchell

iTrader: (15)

What timing/fuel are you running now?

stevieturbo

With such a mild cam, and springs good for 650...and such low boost. Nothing is pointing towards valve float.

Could be as simple as the plugs or wires breaking down. I assume your ignition system is in good order ?

smokinz

iTrader: (2)

the timing was ok, actually a little high at first then the tuner lowered it like 4 degrees.
I will have to check my tune for exact timing but i think its somewhere around 24 degrees @ wot??? and fuel, i have 42lbers and duty cycle is at 80%, intank 255 lph pump and a 255 inline pump, 94 octane.

opti has like 2500 miles on it since the 383 build plugs are new and i have new wires waiting ti go on, coil and ICM are older- 5 years old maybe.

ss.slp.ls1

iTrader: (36)

What brand opti? I would do a coil continuity test or replace the coil (they're cheap). Also do you have the ICM mod done?
Have you monitored your fuel pressure under load at WOT?

smokinz

iTrader: (2)

it is an ac delco opti. ICM mod?- do you mean space it out from the head so it doesnt get heat soaked?-then yes i did. and fuel pressure at WOT is at 42 psi

ss.slp.ls1

iTrader: (36)

I won't hurt to try a new coil then.

smokinz

iTrader: (2)

what do you think, stock replacement or MSD

ss.slp.ls1

iTrader: (36)

I would go with a stock GM coil.