OT, NPC: Aluminum block time-certs, Do I do all head bolts on Northstar 4.0? Options

[aircooledboy]

I have been turning a lot of wrenches lately, unfortunately on a 98 Olds Aurora with a 4.0 aluminum block "little Northstar". Had an overheating problem that I finally narrowed down to a head gasket issue.

Pulled the be-och out, got her apart, all checked out, and cleaned up. I get to putting the heads back on, and things go south. (IMG:http://www.914world.com/bbs2/html/emoticons/mad.gif) The head bolts are stretch bolts. 1st torque is to 30 lbs, then 70', 70', 60'. I get the first head on with each bolt torqued to the initial 30 lbs. When I went to do the first 70', the 2nd bolt spins. (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) Pull the head back off, put in a standard time-cert, try again. Get head back on, get all to 30, start to do 1st pass of 70', a different bolt spins. (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) I decide to see what the other head will do. Again, the 2nd bolt I try to turn to the initial 70' spins. (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mad.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/flipa.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) I didn't try any more.

So, 2 questions:
1) should I just bite the bullet and just time cert all the head bolt holes. On the one hand, I don't see and good alternative, but I am just reluctant to drill what might be perfectly good threads out. on the other hand, the head gaskets are $50 a pair, and I have already ruined one set.

2) In doing some research on the net, it looks like GM's kit for this bull caca uses an allegedly different design of insert for the aluminum block than the standard time cert. Does it matter?

An other input is greatly appreciated as always. (IMG:http://www.914world.com/bbs2/html/emoticons/beerchug.gif)

[Mueller]

QUOTE (aircooledboy @ Nov 7 2005, 08:07 PM)

How about strength of time sert v. helicoil. ???? Anybody have experience with helicoils in aluminum? I can helicoil all head bolts for about $40. Time sert kit with enough extra inserts to do whole block = $400-600. (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif) ?

I guess you didn't see the 2nd kit TimeCert sells (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

It's made "just" for HeliCoils (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)