Hey guys, I took the head off my D15b2 and had it sent to get ported and polished, and was wondering about the head bolts. I was told that they stretch. I showed a buddy one of the bolts and he said I was lucky because the bolts I have aren't stretched. Just to be sure can anyone post pics of a bolt stretched and unstretched? And yes I've googled it and found nothing. The one's I have got the twist threads on top and normal threads on bottom. I appreciate your time thanks.

 

You can reuse if you are tight on funds, make sure you go 10 ft/lbs over spec. Personally I don't recommend it, and you can usually pick up a new set at Napa for under $40. I'd go new if funds allowed.

 

Bolt stretch would not be observable in a photograph. You need a stretch guage or big(!) micrometer to find the stretch, and it is usually measured in tenths of a millimeter or thousandths of an inch.

This article explains it pretty well, i would say. You just have to ignore the fact that they are talking about rod bolts and think about head bolts instead.

The main difference with head bolts is you can't measure it when its in the block. because of this, i recommend following the OEM procedure, which is to lube each bolt with clean engine oil and torque to factory spec of 47 ft/lbs in 2 stages, first to 22 ft/lbs and then to 47 in the correct order. If you do that, you can likely reuse your bolts. I would not recommend over torquing them. I also don't think i would re-use the bolts more than twice. It is likely honda built in a large margin of safety with respect to the yield strength of the bolts, but i would rather err on the side of caution.