Mark A. Rogalski

iTrader: (1)

Car is stock with Long tube headers and custom exhaust (pics). Work is being done at Extreme Motorsports, Temp AZ.

Recap: OEM rocker failer (needles in the pan) was the reason for this process

1st Visit:
Installed Crane 1.8's kit (rockers, pushrods, guide plates, ect.) and their double springs. Installed all new ZO6 clutch assemble, flywheel & hydraulics
LS1 Edit Dyno tune
Knock sensors tripping and 4 degress of retard occuring about 3k RPM on up.
No noticeable sound of spark knock.
Readjusted the rockers per VHP method
Still 4 degrees of retard from knock sensors picking something up

2nd Visit:
Replaced the knock sensors
Replaced intake with SLP LS6 intake
Readjusted rockers per VHP method
Still 4 degrees of retard from knock sensors picking something up

Had dealer install all new engine and tranny mounts.

3rd Visit:
Cleaned the fuel system with additive (2 tanks) before coming in
Ran 100 Octane fuel
Still 4 degrees of retard from knock sensors picking something up

Replaced the cats at the muff shop. I discovered they were falling apart, plugging up flow, thought this might have been the holy retard grail!!!!

4th visit (this week):
With open headers the retard seems to reduce. When full exhaust is attached the reteard is still 4 degrees. Headers do not touch anywhere at anytime, nor does the rest of the exhaust.

Run 010 - base run this week (after all the above work)
Run 012 is after a tune with full exhaust, still 4 degrees retard
Run 013 is after another tune with full exhaust, still 4 degrees retard (324.7 HP....hard to read)
Run 014 is with OPEN HEADERS! HP drops even though retard went to 1 degree or so.



Blow up from 3,500 RPM to 6,000 RPM


Ideas I've heard so far on why so choppy and all the retard in timing?
The Crane dual springs, need to be changed
The Crane rockers are too heavy for the OEM cam
blah blah blah.

zo6vetteman2003

iTrader: (1)

The dyno sheet looks alot better. I think the exhaust work paid off, and was masking the other noise being picked up, but you are on your way to solving this it seems.

Mark A. Rogalski

iTrader: (1)

Thanks,

Extreme Motorsports and myself are really at wits end on what to do next to fix this issue. My question is why is the graph so choppy and what to do to fix it and the retard issue.

Any really good ideas with first hand experience.

Rick@Synergy

iTrader: (5)

you talk about knock retard, but what timing are you realy running?

Rick

mrr23

iTrader: (3)

vettenuts

iTrader: (4)

Yes, can they record the timing during the run? Also, where is your AFR plot, do you have it. I don't think it is the Crane parts, if we were 1,000 RPM higher then you might be more justified in looking into the valve train, but not at 5,500 RPM. However, having said that, have you measured your spring load as installed? I seem to remember you had some early issues with the Crane installation and "if" you did surge the springs the springs may have weakened. Easy check if you have the tool. My other question is lifters, how many miles on them?

lilbuddy1587

iTrader: (1)

Your biggest problem is going with Extreme in the first place. They cant tune for ****, period! Every car that has been tuned by extreme has been RETUNED by the same guy that tunes 90% of the fbodies in AZ. I've seen it first hand. Such as the turbo/nitrous vette that only put down low 500rwhp on 10psi.... Nic00z28 here on the board I believe.

Mark A. Rogalski

iTrader: (1)

I think the timing is set at 22 degrees for the 91 Octane we get in AZ.

Rick@Synergy

iTrader: (5)

Now at the 22 degrees in your table, are you leaner or richer?

Rick

Mark A. Rogalski

iTrader: (1)

I blelieve it is all good and set at 12.8. I will ask Xtreme to chime into this forum. They are really commited to helping me out here and have been very good to work with and tolerable of my expectations that everything be perfect.

Rick@Synergy

iTrader: (5)

You need alittle more fuel than 12.8 if the timing is 22 degrees. More cylinder pressure needs more fuel. If you want to run it leaner, then add some timing to it to compensate for less cylinder pressure.

Rick

98Z28CobraKiller

iTrader: (17)

I would try taking it to another shop. Sometimes it takes a fresh outlook. It's like looking for a pen on your desk at the end of the day. It could be right in front of you and because it has been in the same spot all day it just fades into the background. Having worked at and hung around many performance shops, there is always the nightmare car. It seems that you are the lucky one. They may just be frustrated and have a negative outlook and not be able to get past it.

It is possible that you are loosing timing because you live in 110+ weather. I believe that your really bad retard was happening during the summer and now that it is winter it isn't as bad.

Last but not least, I hate to say it, it could be an internal engine problem that just happened to happen after you made the valvetrain changes. If all else fails, pull the motor and have someone go thru it.

Orange Peel

iTrader: (20)

Have you put new knock sensors in at all? Are the stock ones maybe overtorqued, they can be more sensitive if they are torqued too much. I would take the intake off and look at the sensors, try different ones and see if that helps, if not, there's something else playing into this.

Mark A. Rogalski

iTrader: (1)

Yes I agree. I'm sure they would be happy if I took it to another shop. Right now, I can't justify walking away from the $5,800 path they have led me on. The timing, regardless of temp, has always retarded 4 degreees.

Orange Peel

iTrader: (20)

I would put stock rockers back on and redyno, could be the rockers, why not try it, very quick and easy. You may have overtightened the new knock sensors as well. Supposed to be like 12ft lbs if that.

98Z28CobraKiller

iTrader: (17)

Well, if you are unwilling to go elsewhere, then I would make them pull the motor and go thru it with the understanding that if something is broken in the shortblock (which, if I followed the story correctly, has not been opened up yet by them or anyone else), you will pay for the labor to pull it.

I had an old 81 Z28 w/ a SBC long block that I had built at a machine shop. I put it in the car and everything seemed to be running correctly but I had detonation. I did everything you can imagine to try to fix it w/o pulling the motor (I assumed that it being fresh, it couldn't possibly be an internal problem). Finally I pulled it, 3 bent pushrods because they did not measure them with the valve train in place and they were too long.

Mark A. Rogalski

iTrader: (1)

Going with a set of Harlan Sharp rockers crosses my mind every day (or similar OEM). I am waiting to see what the shop suggests. I'm not a mechanic, not that I can't, just not worth my time, and have found myself trying to troubleshoot this thing myself.

I think pulling the heads and going through them thoroughly might be a good next step.

Beast96Z

iTrader: (21)

Have they tried de-sensitizing the rpm band that is being retarded? Could just be false knock and just needs a little work in that band. Shurly a performance shop would have a set of OEM rockers laying around you could swap out before buying others. Hell I've got 2 pair laying in my room.

vettenuts

iTrader: (4)

It is not the rockers. Everyone seems to like blaming these rockers, but they are quieter and have lower rotary inertia than stock. The Harland Sharps do have higher inertia so you will only be making the situation worse!!!

I really believe you have a tuning issue. My tuner had to desensitive my sensors because we kept getting false knock and that was before the rockers. I still think you need to check your installed spring pressure as well, right now you are in the dark with regards to how the springs have handled all the goofs by this tuner.

Mark A. Rogalski

iTrader: (1)

I agree that it is probably not the rockers themselves.

I have Crane:
144759-16 Crane 1.8 ratio rocker arm kit (Includes screw-in rocker studs, pushrod guide plates, and pushrods)
144832-16 Dual valve springs
144661-16 Titanium Valve spring retainers

We got these straight from the Crane press release "Street Shark" Vinci project car. I wasn't trying to cut corners as you can tell.