I've bought the thick "Williams Washer" for the other 5 studs, the ones that do not attach intake and exhaust together- they were with the bolt kit from MSA, are lock washers not required on the exhaust manifold or header?

I don't have any lock washers on any of the intake oe exhaust studs or bolts. The only lock washers are on the carb to manifold connections. But I will be watching this thread for input.

No lock washers. Just installed triple webers with new intake manifold and new intake and exhaust gasket and new studs and washers....no lock washers...and none came off the old studs.

I just took the ones off my car on the fourth. No lock washers anywhere for the manifolds. I think they would give a bad torque reading if used.

The nuts used on the exhaust and intake manifolds are essentially self-locking because they are slightly out of round. This is why you won't find lock washers on them. Hope this helps..

I'm going to put 2- M10x1.25 Toyota studs in my cylinder head. 1st bolt under thermostat housing and the last bolt before the firewall. Those were wallerd out big enough that I might not have to drill before the thread tap, exageration but they are threadless about 1/4" going in. I don't think Loctite will be enough on the M8x1.25.

Run the proper size drill bit down the hole by hand before you tap the head to be sure you don't brake the tap off in the head. Then open up the hole in the sprung washers to accept the bigger hardware.

Rainman I've been reading up on "slightly deformed nuts", sounds like the middle of a joke, they say that they work good without lockwashers but only once. Mine are new but someone might find this useful.

What you are saying is correct, somewhat. Deformed thread lock nuts are one shot, you need to replace the nut and stud or bolt if you remove the nut for service work as the thread deformation causes gauling of the male threads which is the locking mechanism.

We have a deformed nut, meaning the thread is slightly out of round, but not so bad as to damage the threads when removed. When you reassemble the nut and stud connection it should go together tightly, meaning you can't turn the nut onto the stud without the use of tools. As long as that is the case you can reuse that hardware, if you can fully engage the male and female threads by hand you need to replace both stud and nut because they are worn out.

Hope this helps.

Ok I have some more info on exhaust studs from my local Nissan Dealer. I carried one of the studs and nut from MSA, M8x1.25, and asked about a M10x1.25 stud and nut. He had some from their 8 cylinder pick-up, #14064-JG30B STUD $1.98, #01223-N0021 NUT $1.06. that matched length wise and the nuts are truly out of round. You can't tighten them past the last 2 threads in the nut without a socket where as the MSA nut would spin all the way down to the shank on their stud. Parts guy said that those nuts were NOT deformed or out of round because they thread down so easy. He said I should mash them with a vice a little to make them out of round or buy the ones he sales. He has been selling Nissan parts since '85 and said that he's never seen a nut you could tighten all the way with your fingers on a manifold stud. Exactly what 5thHorsemann said. I don't think MSA got the right nuts for me, maybe I'm the only one?

Edited July 11, 201212 yr by siteunseen

One could just go and buy such apparently "magical" out of round self locking nuts and use them with the stud of your choice avoiding the dealership. I believe they are just run of the mill conical self locking nuts. Their tips are staked, deforming the end of the conical nut. The entire nut is not "out of round". A favorite supplier of mine is Bel Metric. They have them with and without flanges in either the usual 8x1.25 or 10x1.25 if you use a larger stud.

https://www.belmetric.com/metric-nuts-top-lock-flange-nuts-c-3_54.html?zenid=5pqdalupf8j63msv7pldqra8f6

Nevermind..

Edited July 11, 201212 yr by Rainman