350 BIG truck BLUE smoke!

I recently rebuilt my 350 L82 4 bolt main engine with KB flat tops, steel crank clevite bearings, comp cam, 882 heads ported/polished & gasket matched and after 1 year I added more goodies to raise my compression (deck plaining) head gaskets(composite) and now whenever I'm on a steep grade going up or just plain hammering the throttle blue smoke exits the rear(ONLY WHEN RPM's ABOVE 3500)...the oil is somehow blowing by the very back pistons of the block....compression checks ok, all gaskets were replaced, heads re-done......everything but a leak down test....could this be that the crank case isn't breating enough and forcing the oil past the rings as it rides up the pan towards the skirts of those back pistons........The oil burning is only under heavy load?throttle or steep hills....there is no oil burning at idle, or at star up or at average driving(RPM's under 3500).......if anyone has any idea what this could be or any suggestions that don't include oil additives in it would be helpful....thanks

Hey I dont have a blazer i was just checkin out this forum for a friend, But i do know that blue smoke is unburnt fuel, so i'd say you are running to rich, white smoke is water being boiled and expeled and useally indicates a blownhead gasket and oil is most likley going to be black or close to it I hope that helps fix your prob, later, josh from 3rd gen honda accord peps. :frog:

If your running rich then you need more air. Get a K&N 14"x6" high rise open air element and a 1/2" throttle body spacer and cut a hole through the hood and put a ram air scoop over it to keep it dry.

check for positive crank case ventalation. does right vale cover have a breater? & make sure pcv valve isnt clogged up on left valve cover. if you are buildind up pressure in the crank case this will fix it. i allways heard that black smoke comes from carberator loading up . blue is burning oil 966969

Fouling the back two plugs on a small block chevy is pretty common. What is the carb, size of the cam and what gas are you using? Also, what are you using for fire to the plugs?