I have a 406 small block, that when it hits 180 degrees will smoke white out the tailpipes. I'm thinking of pulling the heads.How can i determine if its a head gasket, cracked head or block? This engine has almost no miles on the rebuild but has been started and run a lot while the car was under resto. I was planning on ditching it and gettig a HO 350,but thought i should check into it since i did put some good money into the rebuild and if its only a head gasket it would be an easy fix. The engine has always ran real hot since the rebuild, even shot up to 270 while idling when the electric fan didn't kick in and i didnt notice until to late. If i can narrow it down to a cracked head, im thinking of going with the Vortecs, but i dont want to buy heads if its the block thats cracked.Any suggestions on how to go about diagnosing this?Thanks!

Did you use 350 heads? If so did you drill the steam holes? White smoke means coolant in combustion chamber. Check plugs to see which ones. This way when you pull the heads you can have a place to start.The ones that are leaking will have a steemed look.

Originally posted by boomhauer:
Any suggestions on how to go about diagnosing this?Thanks! First I would let it warm up good then shut it off and see which cylinders blow water out open spark plug holes.
Then I would pull the heads and have them checked.

Usually when head gaskets are leaking a little, the white smoke will be much worse after the engine has been setting a while and not started but will go away pretty quick.
The opsite happens with a crack, as the metal warms up the crack will open up and allow more water into the cylinders.

Thanks for the suggestions, Only problem is now it wont run. :(