I am back into the 98 Buick LeSabre. For a year the car has idle rough and when it threw a code it would be lean bank. I checked for vacuum leaks but never could find a "ah, there it is". If you look you can see where I posted about seeing the gasket at the throttle body and plenum. Never got a definitive answer on that one. I did convince Dorman to send me a replacement plenum. So here I am tearing it down all the way to the lower intake in case the lower intake is leaking. It should not have been considering the work I did the first time. I used Felpro lower intake gasket the first time and I was not happy with the quality but I used them and got the engine back together. This time I am using Magnum and I like the "looks" of them much better than the Felpro gaskets. However, this is not about gaskets but about torque.

My question is why is the torque so low on the lower intake manifold; it is around 132 inch pounds. I would think the lower intake could take a higher torque than 132 inch pounds. It is important to distort the gasket material to get a good positive seal. That is how it works, you put a squeeze on it, it distorts, flattens against the intake and heads and seals the ports. Now of course the original gaskets had a plastic carrier; could that be part of the reason for such a low torque? How did the engineers arrive at 132 inch pounds for torquing the lower intake?

You would have to ask the engineers, but I suspect much higher than that could distort the intake manifold.

Preventing distortion of the intake is done by torquing in steps and following the proper sequence of tightening the bolts.

There are two types of engineering, real engineering and engineering to satisfy the bottom line. Unfortunately, today engineering is the latter. A prime example is the ignition switch on GM cars.

For reference, 132 in-lbs is 11 ft-lbs

I am a registered professional engineer, and am quite capable of doing the conversion. As far as engineers making errors, I wear a ring on the small finger of my working hand (right) made from iron salvaged from the Tacoma Narrows Bridge as a constant reminder of the potential consequences of errors. If you are not familiar with the context, google Tacoma Narrows Bridge. When my son graduated from engineering I had the honor of presenting him with his ring at his "Calling of the Engineer" ceremony, and it was also made from the same iron. Oddly enough, it is referred to as the iron ring, and every engineer in Canada wears one.

Is there any other wisdom you would like to share about engineers?

Which torque are you using? American or German?

Seriously, if you are using a cheapo click style torque wrench, they are far from accurate at the lower end of the scale. 11 ft lbs on the average 5-80ftlb wrench isn't good to use.

I am an engineer myself so I can BS with the best of them. Let'* talk about engineering, who was the genius at GM that decided you can put a hot metal pipe in contact with plastic that had a coolant jacket behind it?

George Schmidt.