355 inch sbc, 13:1 compression ratio, solid roller camshaft, brodix track 1's. The problem I am having is when we set the timing (locked out) and as the motor grabs rpm it slowly retards the timing. If it's at 34 at idle, then it'll be at about 28-26 at 5000 rpm. We have checked end play in the distributor, thrust in he camshaft, changed distributors, changed dis gears, used 3 different timing lights and all the same result. WTF do I look next. I'm lost bigger than shit..