davekuhar

Hello,
I have a 1997 sc400 and i was told to torque the head bolts at 29 lbs and then turn them 90 Degrees??? Is that true?? I've never heard of that. I would think you torque to specs and that's it! please help, because i want to get it right.
Dave

soarer13oy

iTrader: (13)

Yes you mark the bolt and after you torque it to 29lbs in sequence, you then go back and tighten the head bolt by turning it 90 degrees.

StiCk3

iTrader: (5)

the extra 90 is for the bolt's torque-to-yield setting which stretches the bolt a bit and gives it maximum clamping force that no torque setting can properly match. The downside to this is you have to replace the head bolts every time they are removed as the bolt is stretched to it's max. Hopefully you're using new head bolts... good luck

spdrcr771

iTrader: (21)

Im told by my buddy/factor lexus tech/supra guy. that they (lexus) never change the factor head bolt, unless they fail to meet torque specs/ or fail period durning install. I was going to buy all new ARP studs & he told me that it was a waist of money, that my factor studs would be just fine. I had no problem doing my 1.3uzfe build with the same studs. The vvt-i torque specs are are even higher 44lbs. Here is a couple of pics of the 430 repair manual for your viewing pleasure. Dont use the torque spec but the sequence should be the same.

StiCk3

iTrader: (5)

I also work at a toyota dealership, and there conflicting stories. On one side, there are blown up schematics in engine manuals that have notes next to certain parts that say not to reuse, and head bolts are one of them. On the other hand, we get the occasional rebuild here and the techs re-use the bolts without any problems. I figure while you're in there, give yourself peace of mind and replace them rather than risking a broken bolt or a blown head gasket and starting back at square one because you didn't spend the extra dough on those internal parts. That's just my personal opinion, but if it works for you then i can't argue with that