[wetdog]

Hey , this is my first post but its a burning question that maby some guru will know. I recently rebuilt my 258 in my 86 cj , it runs great except for onr thing if I idle for too long say 4 mins it starts to burn oil . As far as i can tell it might be the valve guides what do you think ? when driving around it burns nothing , passes smog , and uses hardley any oil between changes ??....thanks in advance .

[Mike Romain]

That sounds to me like it is choking out which blows black. I would open the air filter on a fully warmed up and running engine and make sure the air filter isn't full of oil as well as making sure the choke plate is straight up and down.

Did you mess with the carb mix screws and do you have all the stock emissions parts on there with the computer that runs them?

[wetdog]

Mike , I have the mopar fuel injection , I have checked all lines ..PCV and so forth for oil and found nothing . The only part I didn't do myself is the head which leads me to believe the valve guides have excessive clearance.Do you think that would cause this? Mark

[Mike Romain]

Originally Posted by wetdog

Mike , I have the mopar fuel injection , I have checked all lines ..PCV and so forth for oil and found nothing . The only part I didn't do myself is the head which leads me to believe the valve guides have excessive clearance.Do you think that would cause this? Mark

Wouldn't that be more of a valve seal issue? If the valves leaked at idle, man just think what 4000 rpm would do to them. Parts would be flying...

I think it is more a tune thing...

[wetdog]

The valves have those teflon seals as opposed to the umbrella type could that be it?

[Mike Romain]

Originally Posted by wetdog

The valves have those teflon seals as opposed to the umbrella type could that be it?

I don't know the difference in tolerances, maybe someone else does?

[Coiz]

Leaking valve seals/guides usually gives you the puff of smoke at start up, not sure about extended idle.