Orange Juice

iTrader: (3)

Had H/C installed last week
AS 5.3's and a 224 cam. CompR lifter, Yella Terra rockers. Car has TPIS headers/Ypipe, ported intake and 78mm tb. High fow heads M6 342 gears stock rearend.
Was told that the ported intake had a crack in it, but was repaired before the car was dyno tuned.
On the drive home, after I opened it up a couple of times the idle would hold at 3000 rpm's. I would hold my foot down on the clutch and the car would stay at 3000 rpm. I bought some plumbers patch and jammed it over the intake the idle dropped. got home cleaned it up and epoxied it again.
headed to the strip ran a best of 12.90 at 112 mph. Intake seem to start leeking again. Switched the intake back to the stock ls6, Car does the same thing.
So now the only other two things that I can think of is the tune is very off because the first tune had to correct the leak, or the compR's are not setup correctly.
I pulled a valve cover off and rotated the lifters and tried to see if there was any play. Couldn't find any play in the rockers at all.
Has anyone had this happen, is it the tune.
The car dynoed 395rwhp 375tq

HOTROD98Z

iTrader: (1)

It sounds like there may be too much air getting past the blade of the TB and it's throwing the IAC sensor off. Is the stock hole still in the blade of the TB?

Orange Juice

iTrader: (3)

The hole in the tb is larger then stock. I was going to switch back to the stock tb tomorrow

strokedls1

iTrader: (1)

Check the idle control plunger in the tb. If it is not working right it can cause the high idle.

Orange Juice

iTrader: (3)

Would this have any effect on the HP of the car?

mike m

iTrader: (6)

you better check your preload, that is the most important thing, you dont want to colllapse a lifter.

Orange Juice

iTrader: (3)

Without having to get to the timing set to get tdc, is there some way of checking the preload. If there was too much load on the rockers wouldn't that hold the valves open?

strokedls1

iTrader: (1)

The idle plunger will have no effect on power output of the car. If the preload is too great it can cause valves to hang open a little bit. You need to redo those if they are a problem before the lifters are destroyed.

Orange Juice

iTrader: (3)

I pulled the idle plunger out and connected it and turned the ignition on and off. the plunger moves back and forth. I will get a new one tommorrow. I switched back to the stock tb and that seemed to make a difference. The idle wouldn't hold high for very long but still not rite.
As far as checking the load on the lifters, should I just rotate the engine until I see both valves closed. I was going to stick a piece of coat hanger wire down the spark plug hole but was worried that it might get stuck under a valve.
If the valves were open a bit wouldn't there be some sign of this?

strokedls1

iTrader: (1)

A leak down test would tell you if the valves were hanging open. If they were all a problem the car wouldn't run. Sounds like there is still some unmetered air getting into the intake if you swapped tb's and it is still idleing high. Take off the serpentine belt and turn the motor over with a breaker bar with 24mm after removing the plugs. Rotate the engine until just after both valves are closed on each cylinder. Then loosen them and retorque and check how much of turn it takes to 22 ftlb.