'75 Howard Day Cruiser, 454, Berkley etc. Winter project last year, ran good on trailer, to the lake for test and tune. Ran out of no wake zone, up to 3500 rpm, all good, went to 4000 and engine just quit like turning off the key. Tested with another coil and decided that the MSD must have 'shit-the-bed'. Before you throw yours away, call MSD, they'll give you a return #, ship it to them, then they'll repair and return. I think the repair on mine was $65.00 or so, and all runs good since then (fingers crossed). They were great to deal with and repaired the long out of warranty item with pleasure. Try it!
CC