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I have had an ongoing problem with the manifold bolts loosening up on my 51. The problem children are the difficult to get to ones, in the back. I've got some interference wrenches, which should help. Question: should I use Loktite or lock washers under the nuts?

All tips will be appreciated.

I'd vote for lockwashers over locktite. Would be concerned that locktite would weaken with the heat. In my last life, we always used heat on the "permanent" or green type locktite the factory used so we could break the bond and remove the part. I'd wonder if the same would happen on the car since it would be so close to fairly high temp.

While it isn't quite authentic it would look pretty close so maybe worth using one of the distorted thread type locknuts instead of the regular nut. They seem to be available in what I believe is the correct size.

USe stover (not sure if that is correct name or Not) nuts. The top of the nut is kind of like a caslte nute but is squeezed oblong. Usualy used on critical compnents subject to high heat or other rigorous conditions.

THe problem with lock washers and locktite is the heat. Lock washers are or a spring steel type metal and loose tension under heat. Loctite melts.

The only other option is double lock nutting IF there is enuf thread left to get another nut on to jam against the original nut.

google.com/search?sclient=psy-ab&hl=en&site=&source=hp&q=stover+nut

Those nuts are for SERIOUS situations. They will NOT shake loose!!!

I'll check with the local fastener store to see if they have the Stover nuts. thanks

If they're 3/8-24 most likely any SBC supplier will have them. I think they are used on the exhaust pipe to manifold connexion.

Sometimes used on rear axle flanges of some cars.

If you don't find them locally McMaster has the distorted thread or Stover nut in 3/8-24 and several styles. Personally, I'd go with the centerlock style.

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I would switch to brass nuts with locktab washers.

Those locking nut things may play havoc with the old metal in your Packard. Today's metalurgy is a lot better and takes more punishment.

See pic in HH56's post above It's the oval lock type i prefer. Note that the center punched type (second in pic) come in two different varieties. One variety has a kind of a plastic peg insert that can only be seen from the INside of the nut. I wouldn't use that type due to heat.

Also note that the threaded part of the stud BELOW the nut mite be rusted and therefore any tightening of the nut is only forcing the threads ot the extent it only feels tighter than it actually is. IF condition of threads on the studs is unknown then use a couple of flat washers under the nut to shim it out just enuf to be able to pick up a few extra threads for tightening. OF course that only works if the stud is long enuf.