Difference between hex head bolts and 12 pt head bolts???

[sparkoid]

Just rebuilt my 1.6na.  Bolts that came out of it were the old hex head bolts.  I ordered (and used) a new set, what showed up is the 12pt; same thread, same length, just 12 pt.

Noticed the Bentley has different torquing procedures for the hex vs the 12 pt.  (The hexes get a 3 stage torque sequence to 66 lbft, the 12pts get a 2 stage to 44 lb-ft, then "a half turn with a breaker bar".) 

I erroneously used the torquing procedure for hex'es on the 12 pts.  Need to do the head re-torque at some point, am wondering if I can re-use the 12 pts, or are they some kind special material?

[theman53]

You should use the procedure for the bolts you use. The 12pt are Torque To Yield or TTY and need more clamp. IIRC you can take them to a certain torque and it is the same. I don't know what that torque is but I was thinking it was around 100ft/lbs. If you don't have that much on them I would redo it as the nature of the bolt will make it leak later. Since you haven't had them to the Yield then you should be able to loosen them one at a time and redo the torque on them...make sure to use the correct sequence.

If you had the bentley why did you use the old bolts procedure?

[sparkoid]

Long story that boils down to a dumb mistake.

[sparkoid]

Was reading another post just now re: ARP studs and MLS head gaskets.  MLS a brand name or generic, ie Multi-Layer Steel?  Any preferred brands out there?

Are studs kinder to engine block threads than bolts?

[745 turbogreasel]

The block threads are not a problem area on 1.6.  You can tighten the head bolts till they all break, and the threads will be fine  Maybe not with the studs, but your head would be crushed long before the stud pulled out.

[libbydiesel]

The block threads are not a problem area on 1.6.  You can tighten the head bolts till they all break, and the threads will be fine  Maybe not with the studs, but your head would be crushed long before the stud pulled out.

??    The 11 bolts are known to crack the 11mm block very easily.  The fact that he has 11mm bolts and the weaker block casting is indicated by the fact that his original bolts were hex.

[745 turbogreasel]

Aren't the 11's  on the 1.5?  11MM has problems for sure.

[libbydiesel]

There were a couple years of 11mm 1.6 blocks. 

[sparkoid]

Uh, unfortunately, been there, done that. 

Bentley says they went from hex to TTY bolts mid year '81.  Mine had 11 mm hex heads.  Over-torqued the first (hex) bolt going back in, pulled the threads clear out of the block, they were still wrapped around the bolt.  Had to time-sert.  Ordered a new set of bolts, thinking I would get hex's, got 11 mm 12 pts.

[rallydiesel]

I would not put any money into an 11mm block.