Ok, I need some help here. I have a 68 with a 70 351 W in it.
Recently I have noticed a small puffing comeing out the tailpipes between the nice rumble. I tried Carb first, replacing the old Holly 600 with a brand new Edlebrock 600. Still there. Then I moved to the Ignition. I put in a new petronix ignition under the distributer cap....Still there. I pulled off the Valve Covers to see if maybe a rocker arm was loose, and becouse I wanted a reason to put on some nice valve covers and junk the cheep crome ones...lol. But they were all good.... and the sound was still there. Some one told me it could be a sticking valve? Is there a way to tell without tearing off the heads to have them redone only to find that wasnt it? I have tried to move around the timing from 0 to 12 degrees with no change in the sound. It only seems to be present when the cold idle has the engine around 1,200 rpm and when the car warms up its only there from around 1,700 rpm up.
I hope someone has an Idea for me before I start to tear it apart.