100 Exhaust - torque settings, gasket sealant??

[mbrooks]

I just discovered that my exhaust manifold was loose on the head. On investigation I discovered two studs with stripped threads - PO had tried to get a seal by using washers under the nuts, and in some cases by using steel nuts instead of the correct brass ones.

I now have the manifolds off, and have managed to get all the old studs out by locking two nuts together on the studs [in one case the threads were so bad I had to force a wrong threaded nut on to get the grip needed].

Questions:

1] The manual doesn't seem to have torque settings for the studs into the head, nor the manifolds to the studs - any experience??

2] What if anything are people using for gasket sealant??

3] Are there any differences in the gaskets or studs supplied by the usual suspects?

4] Any other words of wisdom on the job of reinstalling the exhaust and inlet manifolds??

Thanks as always

 

[Dave Russell]

Re: 100 Exhaust - torque settings, gasket sealant?

Hi Mike,

It is nearly impossible to get a torque wrench on the nuts. I tighten them to "all I can pull with one hand on an eight inch long wrench".

The commonly available gaskets usually work ok.

There are a couple of items that will help. Run a large heavy flat file over the flange faces to check for level (no low spots) & correct as necessary.

On the studs that share both an intake flange & an exhaust flange, it is important that both flanges be exactly the same thickness. If they are not, the large washer will not put equal pressure on both flanges & the low flange will have less clamping pressure. The only way that the pressures could be equal under this condition would be if the stud bent sideways which is not likely.

If one of a pair of flanges is lower than the other, put a shim of some type between the low flange & the washer. Unless this is done, you can have the thicker flange tightly clamped & the thinner one so loose that it will leak.

I don't think that sealer will do much good in the long run. Use new studs & brass nuts & new, undistorted washers. Brass is used because it is much less likely to seize on the steel studs. A light coat of moly lube on the threads will help to get proper torquing of the nuts.

Just take time to assure that everything fits as well as possible & it should be good for years to come.
D

 

[jtb55]

Re: 100 Exhaust - torque settings, gasket sealant?

Hi Mike: I have had my head off twice and initally had the sme questions re the manifold and Dave has covered it well. I am posting to note that I also did not use sealant. jtb

 

[mbrooks]

Re: 100 Exhaust - torque settings, gasket sealant?

Thanks both Dave and John.

I have ordered all the new studs, washers, nuts and the gasket and know what I will be doing next weekend!!

Great advice on the flatness check and the shims for any thickness difference. I would have missed that kind of detail.

Mike