98 300ex, k&n jet kit and filter, new timing chain, cobra exhaust. when it gets hot, under load it will ping. if i turn the ignition switch off when hot and crank it over, it tries to crank because it has a hotspot in the cylinder i guess. this is caused by running lean or off time. i also have flat rockers but i don't think that would make it run this hot and ping. but when it is cold, when revved it has a little black smoke out the pipe. what is the deal here. i timed it right when i put the chain on. it runs perfect too. could this just mean that the carb is getting clogged up and making it run lean. it used to run fine with the same setup. i don't wanna blow it up.

 

Smoke out of the pipe = rich

 

i know that, that only happens when revved high and cold. not much of it either. when it is hot it doesn't do it and it pings. running rich doesn't make hot spots and pinging, lean does, this is why i believe it is lean.

 

it won't idle when cold either due to the jet kit i guess.

 

The pinging can be caused by either the jetting is too lean or the valve timing being off.
Next time its pinging...pull on the choke, and if the pinging goes away, the jetting is too lean. If the pinging doesnt go away, the timing is off.

 

you think flat rockers would throw the valve timing off. because i am sure that the timing is correct. i put the pointer on T on the flywheel i believe and lined the marks on the cam parallel with the head.

 

Im not familiar with flat rockers. Was there any instructions that came with them? If they would change the timing, i would think there would have been a warning sent with them.

 

Did you try putting good-fresh-high-octane gas in it?

 

what i mean by flat rockers, i mean they are worn out, and not the shape they used to be in and have flattened areas where they ride the cam. the cam could also be going because of them. i will be changing them soon. yes i put 93 octane and it still did it, tried that last week. i tried the choke test with it on half way and the pinging seemed to stop, so hopefully i have a dirty carb and not have to take the engine back apart. any more ideas

 

hmmm ..... it may be possible you are off on your cam to crank timing or your ignition timing is too advance (bad CDI).