Well I eliminated the fuel pressure as a cause unless 1.5 more PSI is a problem, though I can't see it causing vibration.

Rented a tester kit from the local parts store tonight. Mast requires 58.5 PSI at the fuel rail and I have dead on at 60 PSI according to the tester. Since I can induce vibration just by increasing RPM's in neutral there wasn't a need to test it under load. When blipping the throttle I see a split second 1 PSI dip.

On to tripple check the engine mounts and trans mount and then it's time to pull the tranny and check the clutch.

I was thinking I can take the clutch off and run the motor with just the flywheel to see if I still get horrible vibration at 2K RPM's. If it's still there then I may need to borrow a flywheel or get the balance checked at a shop.

Will keep you guys posted.

At least now you know the pressure is out of the equation. Pull a few plugs and see how the mixture looks as well.

I actually decided to run a compression test as well. I'd say the car is running a tad rich based on the exhaust fumes. Plugs generally looked good with 2 or 3 plugs looking noticeably rich. Not carbon build up rich but more black in color.

Are you running a pilot bushing or bearing in the end of the crankshaft? I had a similar vibration on a car once after installing a new clutch. I chased the vibration down by a damaged pilot bushing due to install. I replaced it with a bearing

I went down this road also Chad when I first put my GM crate motor ZZ454 in years ago. Same exact vibration problem, except I had an automatic. Did nearly all the same things you're doing. Compression check, fuel pressure check, spark plug and wires check(and distributor), harmonic balancer check, mounts check. I eliminated some vibration when I found a bad spark plug wire arc'ing over to my block causing a misfire. But still had some vibration so I then detached the torque converter from the flywheel and shimmed the transmission back to allow the engine to run while detached from converter. I noticed very little vibration then. So, to make a long story shorter, most of the issue was with my flywheel and how the converter was bolting to it, and a new flywheel solved that. I still had a slight harmonic vibration between 1500 and 3000pm after all that, but it was basically just a result of a big cube motor and I came to that conclusion when I sat in somebody else's ride who had the same ZZ454 and it felt exactly the same at the steering wheel.

It drove me nuts for quite a while so I hope you get it sorted out soon and it's something simple. :thumbsup:

I don't know. I had a shop assemble the sub and they installed the pilot bushing/bearing. I'll know soon enough I think.

Thanks Chris.

I think I eliminated tune or engine running incorrectly as a cause of the vibration. I took the car for another diagnostic drive tonight and the vibration is there upon deceleration as well. I even turned the car off in gear decelerating down from about 3.5K rpms and its the exact same vibration. So I'm convinced it's mechanical, rather that anything else.

I have to go out of town this weekend but I plan to pull the motor next week.

Regarding the oil pressure I ordered an adapter for my other sending unit and can play with that next week too. However, when I did my test drive tonight I noticed that at cold oil temps I have a ton of oil pressure (50 idle cold and doesn't drop below 35-40 until a good 10 mins into driving (not idling). If I rev the motor with cold oil it will hit mid/high 70's PSI.

Cold oil pressure doesn't mean much. I've had small blocks with wore out bearings down to the copper have great cold oil pressure and no hot oil pressure. Pull that pan and check the oring while you have things apart.

Agreed. The point I was trying to make was the high cold oil pressure makes me think the sending unit isn't the problem and the reading is accurate. Meaning yeah I gotta pull the pan

Pro Touring Post
 

Hey Chad super nice build,:thumbsup: Not shure you would have the same set up as this guy does (project Schism on Pro Touring .com) but I read on his post page 2 about measuring the radius of the belhousing to make shure the shaft is centered on the crank, or it may cause a vibration a eventuly bearing failure?? just a thought sense you are having a vibration of sorts, he is running an LS3 with a Whipple charger I think, Hope you get it figured out. :thumbsup:

Well I've been working on the car a little bit each night this week. After failing to get up the motivation to even touch it Monday I made a deal with myself to at least do an hour a night.

So after a few nights I got the tranny pulled and flywheel & clutch out.

Let me just say that trying to pull the tranny without draining it was a bonehead move. I made a huge freakin mess and still have to add fluid. Oh well now I know.

Also, learned that a torque arm and tight exhaust makes driveshaft removal a huge PIA. Luckily I was able to slide it bad far enough to get out of the way without totally removing it. I had a few requests to Magnaflow when I dropped the car off and luckily they did a good job of routing it so I could pull the tranny without totally removing the exhaust.

As far as diagnosing the vibration I did start it up with the clutch removed and just the flywheel installed. Vibration was still there. Today I dropped the flywheel and pressure plate off to get checked and rebalanced if necessary. They won't have it done until next Tuesday at the earliest so I have until then to wonder about the motor lol.

Also found another present from Pomona Valley Customs in the form of a stripped bolt into my block at the top of the bell housing. They installed a totally different thread than the rest of the bolts. What a bunch of friggen yahoos.