timing

back firing on decelaraton shaoul i advance or retard the dist. have the wrong damper on the crank so cant set timing to marks on pulley. runs strong and no heating problems the way it is now.

Do you still have the smog equipment on there?

And you can set to the pulley, you just need to mark TDC on the cover.

Are you sure that the down pipe at the exhaust manifold is tight and not leaking? Thiis is a common source of back fire on decell.

I don't remember what year car this is, but if it had a smog pump a leak at any of the head fittings, whether tube or plug, will do the same thing.