... I take the whole retorqing with a grain of salt. I doubt it was done from the factory. You think they seriously went over every vehicle starting it and tightening bolts for weeks before they where shipped out?
I don’t know what, if any, re-torque is done in the factory assembly line, but obviously re-torque is not required after you drive a new car off the dealer lot.
Comparing what comes down the assembly line at a Toyota factory and what a DIYer does in his garage after 100K miles, after a head job, or installing after market parts are two different things.
Doug Thorley recommends quote: "retorquing all hardware after 20 minutes of operation"
Hooker Headers - Quote: "Periodic re-tightening of header bolts is recommended."
FlowMaster Headers - Quote: "Start the engine and check for leaks. Allow the engine to warm up, then shut the engine off and allow it to cool. Recheck the header bolts for correct tightness."
Doug's Headers - Quote: "Start the engine and allow it to warm up to operating temperature. Check for any unusual noises or exhaust leaks. If every thing is OK, stop the engine and tighten all bolts while the engine is still warm. NOTE: Check the bolts periodically to make sure they have not loosened. Re-tighten after the first 500 miles and then again at 1000 miles."
Retorqing/checking header nuts after several heat cycles is VERY common.... at least from my experience.... but I'm only 69 years old and been turning wrenches since I was about 8.
My Toyota 1986 Repair Manual shows the spec at 33 ft lbs of torque for manifold to head. When I have re-installed the stock exhaust manifold or installed a new DT header on one of my 22s, I have never torqued the nuts down that much initially. 33 lbs on my clicker torque wrench feels like a lot… just my experience. Please explain how using old or new factory self-clamping nuts allows for accurate torque readings? Since I’ve experienced the studs spinning or pulling right out of the head, I have been careful not to have to drill, tap, and heli-coil the head - which is a real pain-in-the-arse to do while the head is on the engine!!
That's just my opinion - it may be worthless.
Gnarls.
