I had my 312 recently rebuilt.  At 2000 rpm you can feel a distinctive engine resonance through the steering wheel.  This occurs while driving as well as standing still in neutral  I'm wondering if the harmonic balancer has gone south.  has anybody else experienced this?
Thanks, Don

Did you have the engine balanced?

Crank was balanced, pistons and rods were weighed and equalized

A good balance should include all rotating parts. flywheel or flex plate, crank, rods (with bearings) pistons (with rings, pins and keepers) and the damper, if it's a stick then add the clutch cover.

Was the crankshaft dynamically balanced to match the current weights of the pistons and rods?  The answer above was not quite clear on this.  And then there’s the matter of the flywheel.  Automatic or standard?  If a standard, was the pressure plate and clutch disk balanced along with the flywheel?

Lorena, Texas (South of Waco)

If you feel comfortable that this is not a rotating assembly balancing issue, then I’ll suggest performing a cranking compression check on the engine and insure that all the cylinders are running within 10% of each based on the lowest to the highest readings.  You don’t mention if this is a points or a breakerless ignition.  If breaker points, then a worn distributor can create some varying timing issues between the cylinders.  More detail on what your engine combination looks like would help.

Lorena, Texas (South of Waco)

Was the harmonic damper balanced along with the rest of your rotating assembly?

Lorena, Texas (South of Waco)

Have you run it to 2000 rpm with the fan belt off?  Could be the fan blade out of balance or bent.

John - "The Hoosier Hurricane"

my son had a 5.4 in his truck that always had a tremble.it was the fan.i had never heard of this before.

That's a really good point, something to check for sure.

Seems like it would be obvious visually though, with bent blade(s) or something like that? These older solid steel fans give me the willies, I've heard just enough stories about them letting go that I went and bought a new manufacture replacement. Particularly working around them and spooling up the RPMs.

I did re-discover what I already knew or had forgotten, the fan cannot be removed or replaced without first moving the radiator out of the way. The fan bolts are too long. At least on the trucks. So my brand new radiator fan is waiting.