explosions on my 318..

by "explosions" I am assuming you are getting some backfiring through the exhaust.

this can be cause by many things.

first you need to make sure your plugs are good and gapped correctly, good plug wires,cap and rotor,the rest of the ignition system need to be good (points,condensor,coil,blahblahblah).

make sure you have a good fuel filter,carb is properly tuned and is a good carb.

if it has a choke...make sure it is not close when warm and not open when cold.....it needs to function properly.

you need to pinpoint if its something that just happened out of the blue? or just after you got gas? (bad gas),or did you just pull it out of storage and you did not bother putting any type of water remover in the tank?,or does someone really dislike you and poured sugar in your tank? lol.

worn timing chain,worn valvetrain components such as lifters,cam,springs,valves and so on. does it puff blue or white smoke? over heat at all? could be a bad head gasket.

and one of the biggest things I can think of would be timing......your timing might be off if all the above is ok.

how many miles on the engine?,has it been sitting?,when did it start doing this? how long have you had it?

you need to give in depth information for an in depth accurate answer....otherwise a basic description will only get you as far as a basic answer.