Cam cover nuts? which kind?

[Pistacchio sprint 72]

Hello,

On my 1972 Lotus elan Sprint, I have on top of the cam cover, seloc washers then nuts. Stupid classic ugly nuts, open on top.with a plastic collar at the end of the threading.

Now I see on ebay dome nuts. closed on top by a round section.... chromed or sort of.

Can you advice me what was used by Lotus originally? I have seen both on photos.

I have recently discovered that my cam cover was not painted in the correct colour regarding the brand of carb I have, so I would not be surprised if I had to change the nuts on top of it!

Thx

[CBUEB1771]

Stupid classic ugly nuts, open on top.with a plastic collar at the end of the threading.

The stupid classic ugly nuts (nylok) are the correct nuts.

[RogerFrench]

Dome nuts are for pansy cars, not real ones. They can also be a real PITA to get to fit properly. To begin with, you need a spring washer for locking, and that means yet another plain washer on your seloc, 'cause you don't want the spring gripping on that.
Then sometimes they "bottom out", i.e. the top of the stud meets the inside of the nut before it's properly tight. I've even known them come apart - the dome splits off the nut when you tighten it. You have to measure carefully.
I'd like to suggest you buy nice new plated far-from-stupid nylock nuts. Then it'll look like it's been assembled by an engineer.

[alan.barker]

nyloc with plain washer and a little silicon sealer. Please don't tighten much only a little and forget the torque wrench

[Europatc]

+1 on that

[reb53]

Dome nuts ?
Good grief, do you want it to look like an old Jag XK engine ?
Hang on though, rumour has it that that was where Harry Mundy got his inspiration....

Ralph.

[john.p.clegg]

and going further on that....

you'll have to machine either the studs and/or the nuts (domed stainless are nice ) to get a good fit...maybe if you take it one step further by adjusting the stud lengths you can get the correct torque figures..

John

[Pistacchio sprint 72]

Lol !!! thanks for your advices!!!!



I don't want to do any style mistake!!!!

[CBUEB1771]

and forget the torque wrench

Not sure about that, most people tend to over-tighten when not using a torque wrench. The torque specification for the 1/4 UNF fixing nuts for the cam cover is 7 ft-lb (1 kg-m). I bet that most of us over-tighten these unless using the proper torque wrench.

[alan.barker]

imho if you use a torque wrench with the original cork gasket you can go round and round the nuts with the torque wrench until the cows come home

[CBUEB1771]

imho if you use a torque wrench with the original cork gasket you can go round and round the nuts with the torque wrench until the cows come home

I understand your point, I take about two "laps" around the studs just snugging the nut. Usually by the third "lap" I get close to 7 ft-lbs on all of them.

[nomad]

7 ft lb's would be highly dependant on how worn your nylock nuts are. I just go till my arthritic wrist click's!

My nuts have little rubber backed washers under them that are getting pretty tacky. I would think they would be a good addition to prevent oil leaks. So is there a source?

Kurt.

[rcraven]

Regarding rubber backed washers, have a look at this thread http://www.lotuselan.net/forums/lotus-twincam-f39/need-picture-close-cam-cover-t32771.html#p220933.

[prezoom]

I abandoned the original sealing washers used on the cam cover studs, and decided to make my own. I took a round of 1/2" diameter aluminum, on the lathe, bored a 1/4" hole in the center, counter bored with a 3/8" end mill creating a cup to a depth that would accommodate a Viton "O" ring, 1/4" ID by 3/8" OD, and then parted off the cup. The "O" ring is captivated within the aluminum cup, so it will not expand beyond the cup. Completely reusable and they do not leak or weep any oil, as the "O" ring is much fatter than the original, and thus more flexible, providing a much better seal around the stud and against the cam cover when the nut is tightened. Not original, but cured the problem and is not readily noticeable.

Rob Walker
26-4889