strange tapping sound

[calibronco]

when i begin to accelerate the bronco on the street, there is a rapping noise coming from the engine compartment. the noise seems to disappear once i reach cruising speed. not sure if something is rubbing, etc? any ideas on what this might be? its not a squealing noise - more like dull thudding. so dont think its a loose belt. thanks.

76 bronco, c4 auto 302

 

[Bully Bob]

****** timing...

 

[7bronco1]

if its not your timing check your fan shroud for contact from the fan. I had a odd noise coming from my engine compartment. I found my front body mounts had come loose and the body was moving around while cornering mostly. after thinking about it for a minute your body mounts are most likely fine. but a broken engine mount could cause the same issue.