Sounds in the Engine

I have a 86 Chevette and recently the engine was knocking. There was nothing wrong with it before. What do you think the problem is? What can I do to fix it?

A lot of sounds could be described as engine knock. Does it do it when warm or cold? when accelerating or decelerating? Have you changed your fuel type or source? Is it loud or soft? Have you checked for a loose exhaust part?

Also, have you checked the oil level?
How many miles does it have on it?
How’s the maintenance been…kept up?
Is this vehicle new to you?
Has the vehicle any history, such as engine problems?

The oil level is find.
Dont know the miles.
Recently I installed a new alternator, belts, and starter fuse wires.
I have had this car for a while.
Before I had it my friends dad had it and the engine could not drive.
But he fixed that.

I guess it does it when the weather is cold but the car is warmed up.
The engine knocks as soon as I start it.
Hard to accelerate.
I heard I can use a Octane booster.
Has hole in exhaust