I'm using a Haynes repair manual as a reference while re-assembling a 3.4L engine in a 1997 Chevy Venture. The manual says to install the rocker arm assembly; torque the bolts; then tighten an additional 30 degrees. But it makes NO mention of being at TDC while this is being done... Does anyone have more information or first-hand experience w/ this?
Thanks, Scott
Set the pistons so that they're all in the middle of their strokes. This will keep the valves from contacting them as you tighten the rockers down. When turning the engine over (carefully) to install the timing belt you can turn the crank a little and the cams a little. Of course if you mess up things may touch, but they won't bend if you're using hand power only.
BTW, the wrench torque angle meters go for about five bucks at most auto parts stores. Good thing to have when working on late model cars. They're increasingly using torque-to-yield bolts. (Do not reuse this type of bolt.)
"Scott Harless" wrote
The reason that there is no mention of being at TDC is because it's irrelevent on these engines. There is no valve lash adjustment. You are simply torquing the rocker arm and pedestal to the cylinder head. Assuming that you don't mix the exhaust and intake valve pushrods around, it will run fine. The torque spec that you are being given tells you that the bolts in question use the torque/turn method of torqueing them down.
14 ft/lbs + 30 degrees.Ian
There's no issue with the engine position as long as the timing chain is on and properly timed. I've not heard of the torque + 30 degrees on the rocker arm bolts. I'd check a second source to be sure.
"hyundaitech" wrote
That's the GM factory torque spec.
Ian
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