problem with engine swap.
I'm new here but I'm told this is the palace to go for knowledgeable information so here goes. I've have got a 1992 ford f 150 with a 302 and I am trying to in stall a 302 engine from a 1999 for explorer. After changing the head form the 92 and installing them on the 99 engine it has no compression because the valves are being held open. The push rods, tappets and lifters are all identical. The heads are newer model but I don't know what the are from. Any help will be very appreciated. curt.