hi everyone
i finally got around to tearing down my daughters engine. for a recap, this is a roller 302 fuel injected for a full size bronco that developed a knocking sound within 3000 miles. it appears that one side of the engine was getting way to much fuel. the drivers side cylinders were pretty clean. however, the passenger side was where the problem was. number 4 was really scuffed up on the bottom side of the cylinder and the piston skirt was worn away. the other side of the piston skirt was just fine. the other 3 cylinders showed some wear but all on the bottom side. the other pistons were ok. there was a lot of carbon build up on the pistons and between the top ring and middle ring on the pistons. my concern is what caused this washing down of the cylinders. the engine did not run hot and had excellent
oil pressure.
could it be possible that the problem was with the cam profile? 2 different cam companies sent 2 cams. each company admitted that they sent the wrong cam at first. the second cam wasn't much better. i asked for a cam that would provide low end torque and was very specific that this was for a roller 302 in a full size bronco. i also was very clear that the original engine was a flat tappet 302. the first cam each company sent turned out to be for a mustang. the bronco ran terrible and got lousy fule mileage. even now with the 4th different cam the bronco gets worse mileage than the old 250k got. is it possible that the computer misread the cam and dumped to much fuel into the engine causing the scuffing. its still puzzling why one cylinder was ruined and the other 3 showed signs of wear on one side of the block and all cylinders on the other side are ok. all damage is on the bottom of the cylinder walls. all clearances except for the one bad piston and cylinder are within specs. also the rod bearing show some peculiar spots, like the
oil could have been contaminated with fuel. i don't want to build the engine again and have the same problems. most of the parts are new, computer, injectors, etc. i have been told that a cam with less than 200 duration would give the most torque. i was tempted to go back with a motorsport cam but the advertized duration for a bronco is at least 220. hmmmmmmm. any help would be greatly appreciated. these electronic engines are not my cup of tea. if i can i will post pics of the parts. no luck, says that my pics are to big. help!!!!!!!
thanks,
paul
grrrrrrrrrrrrrrrr!