Packard Forum Index » Post-War (1946-54)

Best argument settler on what is correct is the Packard Factory Parts Book. There are no lock washers on the manifold studs.

On a manifold stud hole that goes into the water jacket there is no danger of drilling "too deep", there's only water at the bottom, that is unless there are diamonds hidden there by James Bond.

As some have correctly implied, the block does not get very hot, sealer will work just fine and not degrade. Before metric studs and the internet were available, mechanics drilled to the next size adn retapped the hole. When heli-coils were invented they were often used.

Putting in a metric stud with a metric nut may make a disaster for the next owner who might mix up the nuts and ruin the threads on two studs and two nuts.

I think many people make too much out of a simple repair job.

From the owner of the car in post 6 of this thread he states:
"The nut was barely on the stud, perhaps 2 turns, but rusted in place. And there was no washer"

So i assumed there is supposed to be a washer between the nut and the retainer.

Also from post 3 of this therad from one our more eloquent and knowledgable Packard guru's:

"Exhaust manifolds expand at a different rate than the engine block due to the higher temperatures they encounter, so there must be some freedom of movement, hence the attachment with studs, washers and nuts and the oversized (elongated in some cases) holes in the manifold for the fastener."

Note that he indicates WASHERs are used.

The parts book was no help as it just lists X for the number of washers but the manifold install procedure does state to install the nuts and washers and doesn't list exceptions. Also covers the alignment issue.

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Since the don't mention the retainers at all in the above passage, I believe that is what they are referring to as a "washer".

Bottom line: What is there to keep the nut from loosening??? We're dealing with heat/cooling cycles and vibration conditions on an exhaust manifold assembly.

Possibly the nut carries a SPECIAL part number and NOT a standard-parts part number???

I think the actual shape of the retainer helps to keep the nut in place. Not to many reports of people loosing manifolds because of loose nuts on these engine. Same general design was used for almost 20 years. If someone was really worried about it, a little bit of non-premanant locktite would give some peace of mind.

From everything that I can tell looking at my engines the nut on the manifolds is your standard, fine threaded nut. I've owned straight eights for years, and have never had one some loose.

I've had more than one of the dang studs break on attempted removal, but that's par for the course.

I use brass nuts that came with the car. I don't know whether or not they are original to the car but my guess is that they are. Brass expands more quickly than steel when heated so I suspect that this helps to keep the nut from loosening on the stud when heated. It would also help keep the nuts from seizing to the stud.

I've come across both brass and steel, I would like to think the brass ones are original and the steel ones are replacements from the past. I'd think that brass would be the way to go if you need to remove the nuts for whatever reason.