backfiring ARGH

[Mike A.C.]

I have this problem that's been the plague of my '65 Stang for the last several months. Ever since a damn-near complete overhaul of the top-end (after a bout with piston slap) I've had this crazy repetitive clacking sound coming from the passenger-side lifters.. and particularly in the last few months there's been a problem with backfiring whenever I accelerate.  Apart from a replacement set of lifters, could there be any alternatives?

[myfstang]

Lifter noise is due to lifters out of adjustment, on the too loose side.  Backfiring, if it's lifter related -- which it rarely is (it's usually timing) -- is due to lifters too tight.  So these problems could be completely unrelated.
Valvetrain noise can also be due to bad geometry and other interference problems.

[Ken Moore]

I have the same clacking noise on my 66 289. Ive adjusted the rockers/ lifters twice now. Even gave them an extra 1/4th turn. They still spuraticly clack. I have 60psi oil press. See'ins this car is 40 yrs old and I have to fix the manifold gasket and carb. I will change them. They are probly week or sticking. Check the push rods for straightness. You could try running some crankcase cleaner and or add some motor honey.
As far as the backfireing.. check several things, distributer in good condition, plug wires not arcing or crossed, timeing correct and stable if the mark jumps around the timeing chain is worn. Check for vacume leaks.
Could be cap and rotor, advance unit working?