The cam is a: Lunati 40136 mechanical flat tappet

 

Not a 4/7 swap.

I'm lost, without being there. Sorry

 

I'm the original owner and I'll add what I can to help.

The cam is NOT a 4/7 swap.
The flywheel is an externally balanced flywheel as well as the balancer.

I first experienced a similar vibration when i first dropped the motor in but after only a few miles I knew something was wrong. I pulled the motor back out and was ready to send it back to the builder when I realized after pulling it that I had forgotten to install the pilot bushing. Along with installing the correct pilot bushing I also dialed in and centered the blowproof bellhousing. After dropping the motor back in, all the vibration was gone.
Tim, did you take the pressure plate off and install a new pilot bushing? If so, the only other thing I would look at are cracked motor mounts (the actual frame, not the mounts) or centering the bellhousing. Aftermarket blowproof bellhousings are known for not being true and this is why a tighter clearance trans like the TKO requires you to center the bellhousing before trans installation. You center it with offset dowel pins in the back of the block.

Vents/crankcase pressure: this motor has always had a lot of pressure in the crankcase (as I hear most stroker motors do) and you need to be running a breather on one side and pcv on the other. The pcv pulls extra pressure and a little oily mist and burns it through the intake.

Hope that helps.

Travis

 

Tim,

I have been around the engine for several years, even ran on a 2000 mile trip to Bowling Green. It ran smooth and Travis treated it almost as well as his new daughter.

The motor mounts, etc would contribute to the severity of the vibration, but something is initiating it. I bet when you were doing your compression test at Travis', plug wires were crossed or maybe a plug electrode was bent in the test.

Pull the plug wires off the distributor top individually at a SLOW idle and see if you can isolate which cylinder is initiating the vibration.

Joe

 

Thanks Travis for jumping in, I am worried about the centering of the McLeod bell housing I am using. I didn't have to do anything to get it to bolt up. I not sure what test I should have made to make sure it was correct. The dowel pins and bolt holes aligned fine. I have the transmission out right now, due to the housing broke around the transmission mount. I looked inside the bell housing to check anything I could see, The pilot bearing and clutch seam to be fine. I do have the pcv hooked up with a breather on the other side. I think I have the pressure under control.

 

Thanks Joe, I will run this test tomorrow to see if there could be any wires crossed or more likely a bent electrode. Travis had the wires ran so neat it would have been hard to get them mixed up.

 

Tim,
We're talking thousands of an inch here. The bell housing holes that the bolts go through are big enough for you to shift it around a bit w/out the dowell pins in the block. The dowell pins fix it in an exact position but the aftermarket bell housings are stamped steel and can be off many times. To center it, you take out the clutch/pressure plate, take out dowell pins, then bolt the bell housing back up to the block. You then take a magnetic dial indicator and attach it to the flywheel and zero it on the inside edge of the center opening. You then take readings at 90, 180, and 270 degrees from your initial point. I don't remember what the accepted range is but if it's out something like .01" then it's not centered and will need the offset pins to center it. There have been many posts in the C3 Tech section about the procedure. If you've already got the trans out I'd highly recommend doing this.
Another overlooked thing is the pressure plate. I try to center it as best as I can before tightening all the bolts. If you've got it shifted to the edge of the bolts that might just be enough to cause a vibration.

Did you say it vibrated in neautral and also with clutch pedal pushed in? Did you put any kind of lube in the new pilot bushing? I usually soak them in oil all night before installing...it's basically an oilite and should absorb some of the oil.

 

My vote is on the Pressure plate.... I'd take the Flywheel & Pressure plate and have it balanced.

Richard

 

Well, could this be the problem, When I put the new pilot bearing in. it slid right in (no press fit) I didn't think anything about it. I had the guys at the transmission shop look everything over while the trans is out. They are telling me that the pilot bearing is way to loose. You can slide it in and out with your finger. They recommend burling up the hole and locktighting the bearing in. We have tried a bearing and its to loose as well. They don't make a slightly over sized pilot bushing. Any thoughts?

 

Should be a hot rod item that converts the 383 crank hole to a muncie nose - try jegs, etcetera.

 

Yes, the bushing needs to be press fit. Maybe I was lucky because I just got the pilot bushing from O'Reileys. A stroker crank is just a Chevy 400 crank. I'd try that first before the hassle of ordering from a catalog.