I'd look at the engine vitals first in regards to the vibration. All 8 firing, fuel pressure, engine tune, etc...

My stock LS2 makes 28-30 psi at idle hot. What weight oil are you running? Mast may loosen up their clearances and that could require heavier oil to get a pressure that makes you feel fuzzy. 50-60 psi at redline should suffice, hot.

re: oil pressure Mast did confirm my readings sounded a bit low. I would generally agree 50-60 at redline is good. I'm not running the motor at redline yet but 4K it was right at 40 which is far lower than any of the LS equipped vehicles I've driven and I'm used to motors reaching peak oil pressure or at least high oil pressure far before redline. It currently has the Mast recommended 10-30 Valvoline racing oil in it with EOS additive. I'm probably going to drop the pan and check the o-ring no matter what.

I haven't touched the tune since it's tuned at Mast and they do dyno the motors before shipping. I used to check for all cylinders firing by pulling a plug wire one at a time with the engine running. What is the non cave man way to do it lol?

Currently don't have a way to check fuel pressure but will look into that. I have a hard time seeing fuel pressure doing vibration while the motor otherwise pulls fine and drives fine.

I will add the motor pulls plenty hard with the limited drive I did. Even part throttle mild driving up to 3K RPM's shows this motor is far more powerful than my old zz4 350.

I get more vibration through the steering wheel (no more rag joint, uses u joints) than I get riding through the handle bars riding my 88TCB Harley. My side view mirrors shake like a Harley too...

What was the oil pressure at when they dyno'd it....has it changed since then??

Are you running an electric oil pressure gauge?

I'd start with a simple thing like the gauge and or sending unit if it's an elec gauge. I've had faulty sending units that read low press JMOHO

True, but the T56 specific bellhousings don't have a round surface that's concentric with the crank. The bellhousing follows the shape of the transmission. That's why you need some sort of fixture to check runout.

I was trying to say that I doubt that the bell housing could be so misaligned that you get a bad vibration, yet have the vibration compeletely disappear when you depress the clutch with the car moving. The input shaft is still inserted into the pilot bushing and is still hypothetically being whipped around if the bellhousing is misaligned. Again, I'd look at the engine and the flywheel/pressure plate. Was the pressure plate new and zero balanced?

Fuel pressure is crucial with fuel injection. I wouldn't drive it again until you are able to monitor it. An engine in bad tune will vibrate like crazy.

Chad, great seeing you today for lunch. Let us know what you find out on the oil pressure and the vibration. I am hoping for the o-ring quick fix and hopefully something easy with respect to the vibration. Glad it's running and driving at least.

So did you drop the pan tonight?

D

I don't know the oil pressure at dyno. I am running an electric sending unit. I'm taking the oil pressure readings off my laptop from the ECU. My gauge is also, driven by the Mast ECU.

Ok I understand what you mean now. The flywheel is the Ram aluminum and the GM LS7 clutch. The parts here: http://sdparts.com/details/scoggin-d...enter/sdls7ack If I pull the trans what would you recommend I look for with the clutch/flywheel? I don't know about zero balanced but yes the parts were new.

I'll see if I can get a gauge to check it. I'm running the vaporworx setup but there could be something wrong with the pump I guess.

Hey Doug, it was good catching up with you today as well. The o ring is not going to be a "quick" fix sadly. I got under the car tonight and I need to pull the rack and either lifting the motor and/or removing the transmission. So its going to be a lot more work to get at the pickup. I probably need to pull the trans to check the clutch anyways so I may go that route assuming it's not some weird fuel pressure thing that Todd is suggesting.

Thanks everyone for the help. The advice is much appreciated.

It is something no one ever really thinks of, but when it comes to building a car, putting a fuel pressure gauge in the engine compartment often comes in handy. Also make sure all of your sensors are working properly, i.e. there's no oil on a MAP sensor, everything is plugged in tight, etc.

As for oil pressure, does Mast have a particular set of numbers that they like to see?

Hope you get all these issues sorted Chad!

Matt

If you haven't learned this handy little fact yet, here it is. NEVER assume anything. :D

Thanks Matt. Me too. Mast indicated that warm oil pressure at idle would normally be in the 35-45 PSI range. They didn't give me a high RPM or WOT range.

Ha, I get what you mean and can logically agree with you but you know that is honestly easier said than done sometimes. Probably going to order a fuel pressure gauge for the fuel rail tonight. I had one on my old motor. I can't believe the difference in cost between a mechanical fuel pressure gauge and electric one that you can have in the car though, wow.