I need help from you engine experts! I had a rebuilt 350 put in my 51 3100 about 6 months ago, and although it only gets about 10mpg, it has run very strong and smoke free except for a few ocasions. The first time I noticed it, I was on a 60 mile drive. About 30 miles into it, the truck started smoking heavily for a few seconds every few miles. It seemed to happen more when the engine had a little strain on it, like going up a small hill. The smoke was blue/grey and smelled like oil smoke. 3 hours later, I drove it home with no smoking whatsoever.
Since then, it has done it again a few times. It seems to happen only after I have a hard acceleration at highway speeds, then it may start to smoke a few minutes later. I usually drive it gently, and it never seems to smoke then.
I changed the oil 500 miles ago, and it is still almost full.
What the heck is going on? I'm going back to talk to the mechanic again, but he doesn't seem to have any good ideas about what can cause this to happen.
Thanks for any help!
