Last april I bought a 1979 seville, unfortunately when I bought it, it didnt run. Every day after school I came home trying to figure out how to get it started. Eventually i figured out i had a bad sending unit which is integral to the efi system and i replaced it. Thankfully, the car started but a new problem arose, the engine was knocking. Im not sure what the previous owner did to the car to make it do that. I came here to ask what the problem could be because the knocking is only on the passenger side of the engine. If anyone could give me some info id be more than glad. For reference, ive checked the rocker arms, and changed out the water pump and thermostat. I think i might need another fuel sending unit though because the engine stopped starting again, i think im not getting enough fuel pressure. Thank you for reading

 

I am sorry but I do not know what the "knocking" could be from. However, if this engine has the original PFI 350 and you decide to ditch the PFI and go to a carburetor, please let me know. I am always looking for these units.

 

If your Cadillac has an early fuel injection unit on it, finding parts is going to be a bear. Have you considered swapping to a traditional carburetor?
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I wanted to keep the motor as original as possible, the efi is sort of a burden though, ive really been considering doing an engine swap

 

Joe are you sure its a knock or could it be a tap ?

Here is knock. 20 seconds into video very audible. Overall short clip.

And here is tap. Also 20 seconds in, and equally short clip.

 

If you want to keep the engine stock you'll probably have to source parts from a salvage yard.

http://www.ctcautoranch.com/

https://www.dvap.com/