Popping noise
 

I have been working on my 72 911 Targa engine and have finished up rebuilding just about everything including the heads. The one thing I did change was stripping out the mechanical fuel injections and adding the webber carburetors. No when I start my engine is has a popping sound from the engine, I need help to determine what maybe causing this popping sound is it from the Valves or the carburetor's any help or advise would be great!!

Throw us a bone, Eddie.

Is the popping sound from the exhaust or out of the carbs?

Regarding valves, what is the timing you are using? Did you set the cams using a dial indicator?

What was the lift you dialed in at at overlap TDC?

light popping out of the carburetor throats requires idle mixture balancing and and compensation screws adjusted. Should be done using a slack tube or Uni sync.