Broke In Cam Now Popping Sound

[toofun]

I have a 350 goodwrench motor. I recently copied the goodwrench quest power combo and used a 268 xe cam, 1.6 magnum roller rockers, airgap rpm manifold and trick flow 23 degree heads. I used the recommended comp cam springs and push rods for my application. Bolted it all together, removed the inner springs on the valve springs so I could break in the cam, set the valves and fired it up and broke in the cam. It idles great but when I raise the RPMS to set the total timing, it would pop and backfire. When I shut it down and tried to restart it, it was very hard to get it to start.

If I let it sit for about 20 minutes It would fire back up again without hesitation but as soon as it warmed up and you try to set the total timing same thing would happen. When I set the valve lash on the rockers(hydraulic) I tightened them until I could still twist the pushrod back and forth with my fingers lightly and then 1/2 turn more per the instructions. My buddy says that the reason for this problem is that when the engine is cold the lifters are not pumped up so it starts right up but when the engine is warmed up the lifters are pumped up and expanding so when you increase the rpms the valves are set too tight. He recommends setting the valves looser and let them tick and set them while the engine is running. Could this be the problem? I have checked the #1 position and reset the distributer and it is dead on correct. I also have the vaccuum advance hose connected. Could it be valve float due to the second spring not being installed? I plan on putting the second spring back in first since the cam is already broken in.

Sorry for the long post but really want to give as much info as I can with this post so I can narrow down the variables. ANY INFO WOULD BE GREATLY APPRECIATED. Fine Tuning has never been my forte so Ill leave it up to you experts to chime in.
Thanks in advance

Mark
TOOFUN