i have an 87 w150 with a 318. at high rpm and under a load im getting a knockin or tapping. i can rev in netural to 5 and no noise. does any one have any ideas.

 

Pinging under load? Timing too far advanced maybe? Burning a quart of oil a mile? Try some 93 octane, if it gets better, you might just have a bad ping caused by bad timing, bad fuel, or lots of burning oil.

 

Possibly an EGR valve that is stuck in a closed position or is not opening for some reason.

 

sounds like fuel ping to me...check timing

 

sorry it took so long to get back on but i retarded my timing 3degree and it seem to be running a lot better. i also noticed the guy i got my truck off of had the flowmaster mufflers installed backwards. so i cut the off and flipped them now the truck has a lot more power and runs like a dream. thanks for all the help guys.