Help! Popping noise coming from engine.

ubs said:

I have a 66 289 v-8 Mustang and for some reason when I accelerate a popping noise is coming from the engine. It kind of sounds like it is coming from the carburetor but it a brand new carb. The timing is correct but for some reason it sounds like a can is being thrown around. Does anybody have any idea what could be wrong? Thank you for your time.

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Last time i had a similar problem...sounds like something is hitting the air cleaner lid when you hit the gas, 1 or more rockers had come loose and a valve was not functioning properly because of it.

If you are sure the carb is good and the timing is good, I would pull the valve covers and inspect the rockers.

I had a similar problem with my 289. I had it running on the test stand and had no problems. After I installed it in the car and got it running again I would hear this terrible rap under acceleration. I thought it was timing but here it ended up the valve cover was hitting the rocker!! Start the car with the hood up and the air cleaner removed. While under the hood feel the back(the side towards the intake) of the valve cover to the back of the engine. No. 4 and 8 cyl. If it's hitting you will feel the rocker hitting the cover. Rev it up and see if you could hear it. If that's it just loosen all the valve cover bolts and "slide" the valve cover up hold it and retighten the bolts. If that is the problem and moving the cover up doesn't work, just remove the cover and tap the inside with a hammer and give it some clearence. I had aftermarket crome valve covers and the stamping wasn't that great. let us know how it works out!