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. 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. 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. I decide to see what the other head will do. Again, the 2nd bolt I try to turn to the initial 70' spins. 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.

I don't have solutions to your problem - but a 4.0 aluminum v8 sounds like a perfect 914 motor. Especially since it's a US motor - should be easy to get parts, etc.

I'd get the correct kit from Timecert

GM repair kits

Thanks Mike. I was aware of that kit (although I thought that was a GM pat number). Getting the kit has been more trouble than expected.

Assuming I can get the kit, would you engine guru types do them ALL?

QUOTE (aircooledboy @ Nov 7 2005, 12:39 PM)

Thanks Mike. I was aware of that kit (although I thought that was a GM pat number). Getting the kit has been more trouble than expected. Assuming I can get the kit, would you engine guru types do them ALL?

might as well.

do you want to see more head gaskets and pull the head if another one turns????


so do em all

From what you described already, I would go ahead and do them. Aluminum is horrible for threaded holes. If they are good threads now, they probably won't be later. I usually find that if you feel resistance as you are removing bolts that are threaded into aluminum, there is a good chance the threads are damaged.


Andrew

The guy I sit next to at work just did all of that research on a Caddy with a Northstar that he got CHEAP! He considered doing the GM recommended (as you have now discovered) timecert repair, but ended up selling it off and still making a nice profit.

Do it right, once.

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. ?

I have not used Heli-coils in high strength applications. Strength should be OK though. In fact, aluminum is strong enough. The issue is when there is any slight seizing as the bolt is backed out. I think Heli-coils have a greater tendency to back out than time certs when you remove bolts that are slightly seized to the insert.


Andrew

I can't asnwer that definitively as I've not seen a Timecert prior to installation or seen the process used to install one. I'm told that they "lock" into place somehow. Having used helicoils on the other hand, I do see where one might give you trouble while trying to torque head bolts.

They install pretty much the same was as a helicoil, but use a more sophisticated tool for the actual insertion. The other issue here is that the threads are recessed about 3 inches into the block. With a standard helicoil it has to be threaded down the entire length, which is pretty much impossible in the 2 holes on each side which are also surrounded by a hollow alighnment dowl. That is what actually got me doing some reasearch on the question in the first place.

My common sense (limited as it maybe ) tells me a helicoil probably isn't well suited to a high torque application like a head bolt. I'm just not real excited about spending north of 500 for a tool kit I will use once to do the job.

Yes, I know: CSOB.

I looked at a $400 kit to do one timcert in my 2.7 case so I know how ya feel.

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. ?

I guess you didn't see the 2nd kit TimeCert sells

It's made "just" for HeliCoils

helicoils are ca ca, there is a diagram in one of Carrol Smiths books (Prepare to Win) or in Bruce A Performance Handbook showing the difference between Helicoils and timcerts. I cant provide a scan of the info now since I am away from home (living in a hotel BITES)

The timecert tool threads the insert into the hole, then when the insert bottoms, the tool continues turning on the inside of the timecert, and expands the insert, locking it into place.