Tighten the head bolts, then loosen them then do them back up again?

 

Is that so you dont have to check them again in a few hundred miles or something???

Its called pre tensioning.

 

When you do up bolts they relax and the tension goes out of them, some bolts come pre tensioned but most don't so you put a tension on them (stretch them so to speak) then loosen them but they don't shrink. Then when you tighten them back up they don't relax and go loose.

the z32 headbolts arent stretch bolts, its more to do with giving a solid seal between head and block, squeesh the gasket down

If they arnt stretch bolts, could you use the old ones again?

 

I have bought new ones, but just wondered?

the z32 headbolts arent stretch bolts, its more to do with giving a solid seal between head and block, squeesh the gasket down

 

They don't have to be stretch to need pre tensioning

If they arnt stretch bolts, could you use the old ones again?

 

I have bought new ones, but just wondered?

 

Yes, you can re-use them.

Fook, I just spent £90 on new ones!!!!!!

 

Oh well, go them now.

 

One other thing, I got a cometic metal layered head gasket. Im just a little worried about doing it up and squashing them and undoing and doing it up again.

 

I guess this is right, but didnt know if it would effect the cometic gaskets. Looks like theres bits that crush and seal and apparantley it was a special costing on them too to help seal...............

Fook, I just spent £90 on new ones!!!!!!

 

Oh well, go them now.

 

One other thing, I got a cometic metal layered head gasket. Im just a little worried about doing it up and squashing them and undoing and doing it up again.

 

I guess this is right, but didnt know if it would effect the cometic gaskets. Looks like theres bits that crush and seal and apparantley it was a special costing on them too to help seal...............

 

use the same setting as nissan

I'm not saying a word but TT net have had plenty to say about the cometic HGs :x: Have a look on there and do a search....

Oh, the real answer is - so us mechanics can add an extra hours labour onto a rebuild :rofl: ;)

Are cometic gaskets no good then...?

I read they can not seal properly?!?!?!?!

 

My track record with Z'd is crap so want to eliminate any popential failure, lol!!

Make up your own mind :)

 

http://www.300zxclub.com/showthread.php?t=93357&highlight=cometic