Techno
05-10-2001, 03:01 PM
A machanic at work told me today that all aluminum heads should be untorqued in stages to eliminate warping the heads. I just loosened the bolts, then spun them out. Do you have to take the bolts out in stages or can you loosen them all at once?
Haven't removed my heads since installing them but I don't want to warp them in the future.
Two guys were rebuilding a sight glass that contains 2,300 PSI. Each glass disc has a square cover clamping the disc in place-4 bolts each. These covers were torqued to 10 foot pounds! Even considering the expansion the parts undergo at 1,000 degrees I thought it was interesting that only 10 FT.lbs. were required. 1,300 PSI is from a pump so it still has to hold pressure when cold.
I suppose the bolts would expand anyway so they might still be only torqed at the 130 IN.lB. level.
I bring this up because it totaly amazed me and to point out that torquing is actually an attempt to measure bolt stretch.
Haven't removed my heads since installing them but I don't want to warp them in the future.
Two guys were rebuilding a sight glass that contains 2,300 PSI. Each glass disc has a square cover clamping the disc in place-4 bolts each. These covers were torqued to 10 foot pounds! Even considering the expansion the parts undergo at 1,000 degrees I thought it was interesting that only 10 FT.lbs. were required. 1,300 PSI is from a pump so it still has to hold pressure when cold.
I suppose the bolts would expand anyway so they might still be only torqed at the 130 IN.lB. level.
I bring this up because it totaly amazed me and to point out that torquing is actually an attempt to measure bolt stretch.