Explosines Motor Beetle 69

Greetings friends: I'm currently restoring my grandfather's 1969 Volkswagen Beetle with a 1600cc engine. The electrical system has been completely rebuilt, and a new alternator, a Solex 32 PIC carburetor, and an electronic ignition system have been installed. I drove it for a few days to test it out, and it had a knocking sound in the engine. I thought it was the valve stem seals and that I could just fix it by adjusting them. But two days later, I've noticed that when I start and drive it, it smells strongly of gasoline, and there are backfires when I accelerate, and smoke is coming out of the exhaust, which it didn't do before. I told a friend about the situation, and he said it could be the engine studs, which is why it's losing power when accelerating. Another friend says it's the spark plugs. I'd like your help and some guidance on what I can do to start working on it first thing tomorrow.

Hey, what color is the smoke and the explosions coming out of the exhaust pipe?

black, and the explosions seem to be internal to the engine.

Well, what you have to do is the following. I also have a Beetle. You have to realize that the following aspects are involved in the combustion: spark plugs, carburetor, valves. You should start by tuning the engine and ignition, for which you must gap the spark plugs (it's better if you buy a new kit; I know that's the problem with your Beetle because the same thing happened to me). Since your ignition is electronic, you must time it, then adjust the carburetor (check that your pilot jets are around 115 or so), and finally, adjust the valves according to the recommendations in the manuals available online.

Thanks Panita, it will be tomorrow that I buy the spark plugs and changes. As soon as I do it, I warn you to help me with calibration, which I currently declare in learning.