timing issue?

I was replacing the timing chains on my 4.7 liter and I forgot to take the cam shaft bolts off before I took of the chains off. Is there any way I can get the cam bolts off? I've tried a 350 pound impact but I can't get it off. Any ideas? Also the engine is still in the truck. :doh:

Hey fellas, I've got a 1986 D250 that was my grandpa's and has been in the family since it was new. After years of use on the farm and down the road, it leaked from every orifice possible, so we recently rebuilt it. The build went great and with minimal problems until the end; we are having a...

i say warm because it was fine temp barely over the mid mark on the gauge and then 2 minutes later it was approaching the hot level and it stalled as i was about to turn into the bank and stopped for traffic. when traffic cleared i re started it and pulled into the parking spot and shut down.No...