Michael,
thanks for the backup. My father (now retired), visited Southern Carbs about 15+ yrs ago, well, I guess now its almost 20 yrs ago. At that point we were preparing our BN2 for vintage racing and gathering all the info we could. They told him, that from 3k + the 4 cyc engine develops a harmonic and basically, will eventually, "shake it self to pieces, with out crank damper." We dont have one, and have rebuilt our racing motor several times, and the crank was cracked, but had not broken YET.... Just plain dumb luck on our part. Another tip they said, is the 4 cyc car's exhaust needs back pressure, so a tailpipe to the rear of the car is needed to get max HP.
Would like to know if anyone out there has modified a US damper to fit a Healey. The cost vs one from DW, BIG DIFFERENCE!!