[TR] Vibration in TR 3 Engine

[bob at texmog.com]

Okay, I finally got the engine rebuild from hell in the car and, yes another
problem.
First the background. New AE pistons and liners (87 mm), all new bearings
(10 over), cam checked out as okay and lifters reground, All new valves and
guides, new timing chain. All internal moving parts including the flywheel
were balanced by a local race engine builder, the main bearing journals were
line bored. The distributor was totally rebuilt as were the carbs.

Started the engine up and ran it per instructions of the cam company to seat
the lifters. Engine ran smooth and idles beautifully.
On  driving the car the engine is again very smooth and has plenty of power.
The problem is that as it approaches 2800 RPM a vibration starts, peaking at
about 3000 RPM and fades out at 3500 RPM. The vibration is bad enough to
cause the body panels to all start ringing. At first I thought it was the
drive shaft but you can get the vibration even if the car is not moving
although it is not as bad.
After having the carbs and distributor rebuilt I installed them in my other
car and tuned the carbs so has to have then at least close on start up of
the new engine and there was no vibration it that engine.

  I'm not looking forward to tearing the engine down especially since I have
no idea where to even start looking for the problem.
Any suggestions as where to start looking for the cause of the vibration?

Bob