Originally Posted by drainey48
My dad has a 1972 El Camino with 350 CI engine and 4B Carb. It has 56000 miles, and the car rarely gets driven. Recently, it has developed a loud banging noise in the engine similar to the sound of a backfire. It's a very clean engine, so I know its not the exhaust. Im not sure if it's backfiring through the carburetor. How am I able to see if it's backfiring through the carburetor, and if it is what is causing that problem? I thought it might be a sticking valve, however, I have done some research and found it could be a worn camshaft, bent rod, etc. My dad is weary about me working with his cars internally, so I would like to be able to pinpoint the problem before I start working. Before I truly begin I plan to replace the gas with fresh gas and change the oil. I hate seeing a sick beauty. PLEASE HELP!!
Do a compression test to see if there are one or more cylinders w/low compression. This could be caused by any number of things, but I'd be looking for a worn cam lobe, a broken valve spring or a bent pushrod for starters.
If a sparkplug has loosened or fallen out, that will make a loud popping noise, too.