Mr Roadrunner
Well-Known Member
My father in law recently purchased a 68 Road Runner 383 auto. 3:23 gear. Overall nice car. It ran good enough for a 2 hour drive home, but needed some tuning. Long story short, this engine wants 30 degrees initial timing. It has a lumpy cam, but the only specs I have are .471 lift intake and .489 exhaust. I had the intake off, and checked lift with a dial indicator. This is assuming a 1.5 ratio rocker arm. Engine pulls around 11” vacuum at 750 rpm idle. I initially had a mopar performance distributor in it, but just changed out to a MSD ready to run. This engine runs best with 26-30 degrees initial advance. Starts fine hot. I checked the timing marks with a piston stop, and marks are spot on. I then installed a timing tape, as initial timing is off tab on factory marks. I am fighting with this because setting initial this high, the engine starts breaking up at higher RPM. I know very little about this engine build, but I am wondering if the cam being installed advanced/retarded too much could cause this issue?