LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Unwanted affect of degreeing an LT1 Cam

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Old Jun 16, 2008 | 06:47 PM
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Unwanted affect of degreeing an LT1 Cam

UPDATE! She's running on all 8 now (Freakin finally). My next problem, keeping it straight on the road. Every time it gets into boost, it starts spinning and the rear end tries to come around.
It's hard to tell what the boost level it's getting to and at what RPM when it comes into boost so quickly and the tires start spinning at 50mph. Plus, shortsighted me... I put the boost and A/F gauge down on the console so they look really pretty. Too bad you can't see then while driving cause the farking shift **** is in the way. Lol... Pod on the column, coming up.





I've seen references to bad consequences of degreeing an LT1 cam via offsets. I'm having an incredibly hard time diagnosing why my brand new LT1 motor refuses to fire on cylinders 1 and 5. It has spark, it has fuel, the rockers are opening and closing the valves. I've changed ;
O2 sensors
Plugs (two sets in 4 days)
Injector sets
LS1 Coil sets (I'm using a new LTCC)
Coil Wiring harness
Switched to Open loop
Switched to Speed Density

I've taken the plugs out (this is like I say, only on the drivers side. The passenger side works perfectly) on the drivers side, laid them on the valve covers connected to their original coil and plug wire and turned over the engine. They spark just fine. They get wet fouled, building up a black sooty covering If you run the engine for anything more than 20 minutes.

So, my question is, when my engine builder degreed my cam, if he did it an anyway you can think of, could I be getting this continual fouling of plugs on the drivers side? My intuition tells me, "No way in hell". But I'm on the verge of losing it. I've paid a ton of money and time, missed work, rental car fees etc waiting for what should have been a turn key situation to be just that.
Thanks,
Dave

Last edited by DirtyDaveW; Jul 8, 2008 at 06:30 PM.
Old Jun 16, 2008 | 07:41 PM
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I cant see it being that far off,but I guess anything is possible. Did you ask the builder? I would check the compression in those cylinders,and a leak down test. I hope you get it straightened out.
Old Jun 16, 2008 | 07:51 PM
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is it possible to have those wires crossed for 1 & 5 ?
Old Jun 16, 2008 | 07:52 PM
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I'm getting that request a lot. I just got a kit to test it. I'm waiting for the motor to cool down right now. I haven't done that before but I'm incredulous that a new motor would have a degradation of that level to where it wouldn't even fire. I've even swapped the number 5 and number 1 plug wires to see if the LTCC box was wired backwards on those two cylinders. It made ZERO difference. I expected it to either run great or constantly backfire. Neither one. Thanks for the response
Old Jun 16, 2008 | 08:08 PM
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make sure all your wires coming from the ltcc go to the correct coil for each cylinder, also check all your ltcc grounds.
Old Jun 16, 2008 | 08:14 PM
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Thanks. My prior LTCC was like that, one wire bundle harness/connector per coil. Bobs latest version uses the stock LS1 wiring harness. It just has a left and right connector (1-3-5-7 and 2-4-6-8) In an effort to start the process of elimination, I took off my coils and put on some from a working LS1. No change. I took the harness off the guys LS1 coils and replace mine, just incase the wiring harness was bad. No change. When I crank it, it sounds very even. No indicatioin that one cylilnder is weaker than the others.



Originally Posted by klrz28
make sure all your wires coming from the ltcc go to the correct coil for each cylinder, also check all your ltcc grounds.
Old Jun 16, 2008 | 09:58 PM
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Just did the compression check. Whew....125psi across the board. Still... what the hell is causing this?
Old Jun 16, 2008 | 10:32 PM
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How much trouble would it be to go back to the Optispark? Just to see if it will correct the firing issue?
Old Jun 16, 2008 | 10:36 PM
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It would be farily expensive right now. New opti, new coil, new Ignition control module. new plug wires.
I'll see if any of my houston buds have one laying around.


Originally Posted by ACE1252
How much trouble would it be to go back to the Optispark? Just to see if it will correct the firing issue?
Old Jun 17, 2008 | 09:29 AM
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Check valve adjustment.
Old Jun 17, 2008 | 11:32 AM
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One of the early things I did. It was perfect. Thanks though

Originally Posted by b4cz2896
Check valve adjustment.
Old Jun 17, 2008 | 11:53 AM
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Originally Posted by DirtyDaveW
the LTCC box
I'd do a thorough investigation with this before blaming the cam.
Old Jun 17, 2008 | 12:46 PM
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Blaming the cam? I don't know what you mean.
Can you think of anything I haven't checked or replaced?

What could be more thorough?
2 new sets of plugs
New wires
2 sets of coils
2 sets of injectors
2 new O2 sensors
Compression check
Valve lash rechecked

No matter what, ONLY the drivers side is afflicted and it appears, cylinders 1 and 5 are ALWAYS the non firing cylinders.





Originally Posted by SS RRR
I'd do a thorough investigation with this before blaming the cam.
Old Jun 17, 2008 | 03:38 PM
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Originally Posted by DirtyDaveW
Blaming the cam? I don't know what you mean.
Can you think of anything I haven't checked or replaced?

What could be more thorough?
2 new sets of plugs
New wires
2 sets of coils
2 sets of injectors
2 new O2 sensors
Compression check
Valve lash rechecked

No matter what, ONLY the drivers side is afflicted and it appears, cylinders 1 and 5 are ALWAYS the non firing cylinders.
What about the LTCC box? The lobes would have to be extremely out of whack for the cylinders not to fire. You could always put the stock ignition back on and see what happens...
Also isn't the LTCC still opti dependent for cam position? Wondering if that may have something to do with it.

Last edited by SS RRR; Jun 17, 2008 at 03:46 PM.
Old Jun 17, 2008 | 03:50 PM
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That's what I would do. Put the stock ignition back on and see what happens.



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