- Joined
- May 26, 2001
i have seen this before myself. I do believe that the heads do lift in some way or another. I generally see this happen on the center cylinder. I think that due to the 8 bolts per heads allow the head to flex and lift in that area. .........................
In my 20+ years of working on these turbo Buicks, I have replaced many hundreds of blown head gaskets, lots of these from detonation, but in my humble opinion, many others from too much cylinder pressure.
My thinking is like what is said above. Maybe if the term "deformed" is used instead of "lift", that would be more easily accepted?
The most common place for a gasket to fail is out the top or bottom of the head where bolt/stud spacing is greatest. If it fails mid-way between the fasteners, does not seem to me that this is NOT a lack of clamping force, but too much cylinder pressure pushing, lifting, deforming or doing whatever you want to call it.
My heads are torqued to 70 ft-lbs and have never blown a head gasket in almost 1000 runs. Due to other issues, I have trashed a few pistons. This shows me if clamping force was not sufficient, even with 6 bolts per cylinder instead of 4, I would have blown a head gasket.
Another of my opinions is that lots of failures are due to lack of re-torquing, after assembly, break-in and then a few heat cycles. If no more than stock boost is ever going to be applied, then maybe re-torque would not be necessary - but simpler to be safe than sorry. :biggrin: