Originally Posted by 86---chevy
I changed out my 305 for a 350 and everything was fine for a little bit but now just about everytime i get in it after just alittle running it starts making this grinding noise in the front of the motor, after several attempts to figure out where it was coming from i thinkn its the harmonic balancer rubbing the timing cover. When i put my 350 in i did change this and put a crome one on but should the balancer be back far enough to rub this or is something wrong.
it will start and stop sometimes 5 miles no sound and romp down on it once let it come back to idle and there it is continuos at idle.
Unless you have a damper that came from a SBC engine that uses a reluctor between the crank timing gear and the damper, there should be no way for the damper to go on so far that it rubs the timing cover. This assumes the cover wasn't bent all to hell during installation.
The timing tab might have been bent and is now able to contact the damper.
The accessories, fan blade, etc. could be hitting something- you need to listen and locate exactly where the noise is coming from.
If the cam timing gear was removed/replaced, the bolts holding it to the cam might be backing out and rubbing the inside of the cover.