Any 4.7l gurus here? So my original cylinder heads dropped a seat #1 cylinder. Replaced both heads. It's been 800 miles of absolute bliss, when on the first cold morning startup.....it develops a terrible tap on the #1 cylinder. Quiets down after 15 minutes but never goes away. Pull the coil wire, it stops, replace it and it's back. What could this be on a brand new cylinder head?? Guide, keeper, seat??? Can I check without removing the freaking head for the 3rd time?? Help?? Thanks!

 

I dont know word 1 about a 4.7 but if it taps when cold I suspect your valve lifter is out of adjustment. If there is no " adjustment" you need to set the preload which is another topic. The extra cold shrinks things just enough to make it sound off.

 

Turned out the new head blew the exhaust manifold gasket.