just installed a cam in my sbc the bolts for the cam gear r torqued at 20 ft. lbs. 2 bolts wont tighten right removed and the bolts r strethed whats the problem?? found new bolts ,put thread lock tite on them OK 1 BOLT STILL WONT TORQUE started at 10 lbs,went up 1 lb. at a time until i got to 15 lbs. and bolt streached i thought it was bottoming out ,tried a longer bolt ,went in all the way the stock bolts r grade 5 they streched should i use grade 8? whats the problem?? never run into this before
And? 2 things stretch a bolt during assembly Over torque or low quality bolt. You have one or both of those problems. Try using clean threads with oil on them and see if it torques.
Is the torque wrench a beam type ? http://whatisthetrend.net/wp-content/uploads/2011/08/torque-wrench-types.jpg or a clicker, full of springs and gizmos? http://supertoolss.com/wp-content/uploads/2011/08/torque-wrench.jpg Beam type is based on a basic metallurgical property ( Young's modulus, or modulus of elasticity ) that does not change over time, so is inherently pretty reliable.
Better get another torque wrench. Sounds like if you don't you'll need a new cam. But maybe: No need to creep up on 15-20 lbs. Chances are you stretched the bolts or overtightened them already. When you try to creep up in too small of increments at low values you just don't get good results. Tighten a bolt to say 20 lbs. then try to go to 22 and it will take 25 lbs. to turn the bolt again so there goes the precision. Using a beam will give more precise results but the same basic problem still exists. Snug the new bolts, then got for 20 lbs in one shot.
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