I recently rebuilt a 2.9l and put it back in the truck. Engine started right away. Lots of oil smoke, as was to be expected. After the initial smoke cleared it was still a bit smokey. Now what happens after it sits for few days I start it up and there is no smoke. After 5 minutes or so of idling the oil smoke starts to come out of the exhaust. I haven't road tested it yet or run it at a high RPM. I also haven't set the timing yet. What should be my next step?
I should note I rebuilt the the heads. The engine is a used one from a junkyard. Didn't touch the block. Oil is clean after my few test runs.

 

white or blue smoke? how many miles on the new block? if you dont hear any engine knocking I'd drive it around for a bit to see what happens
maybe do a compression test after driving it?

 

Definately blue (oil) smoke. Weird that it starts smoking after 5 minutes or so of idiling- it doesn't smoke right away. No knocking. When I get around to it I'll check the plugs, try to do a compression test, drive it a bit. No idea of the miles on the block. I have a spare set of heads if I need them.

 

ok blue smoke, so could be valve guide seals or rings. just thinking I'd say if rings, it would smoke when cold and when it warmed up things expand and it would be less?
for compression test, do cold motor and all plugs removed. if you find 1 cylinder low if you squirt some oil in that cylinder and compression gets higher its rings and not valves.

 

Good thinking on the low compression add oil thing. I'm out of town for a couple of weeks and can't wait to dig into this thing. Thanks.