Just got my new motor put back in the boat. It is a 355 SBC with vortec heads. I have heard differing opinions on if I need to re-torque my heads after the motor gets broke in. Is this necessary? And if so at how many hours. The heads are new L31 heads from the factory and new head bolts were used.....I would like to check the torque my self but would like to wait till the end of the season. Thanks in advance everyone...

"Bad-Habit"

Re-torqueing heads is always a good practice to follow. What type of headgaskets did you use? Felpro claims that their perma-torque gaskets don't need to be re-torqued. I have used them on many occassions and not re-torqued. Any other gaskets and I would say that you have to re-torque.

You're better off retorquing. When you start pushing engines you get some different movement.

I'd rather be safe then sorry. Do it....

I am using a GM Performance Gasket (.28 Thickness). And at what time (how many hours) should I re-torque them?

"Bad-Habit"

Run the motor until it gets to operating temp. Let it cool off and re-torque. When you re-torque, loosen each bolt and re-torque one at a time. Use the same torque sequence as you would the first time. If anything stretched, compressed or otherwise settled in it will do it right away. It is probably not really necessary to do this on a SBC but, it can't hurt and you will not be worried about it when you are out having fun with the hammer down. Enjoy.