I’ve used the 61C Cragar SS on my 69 Barracuda Formula S but with long studs. The lug nuts recommended are conical seat 60 degree, Anyone using these wheels and lug nuts on a car with standard lug length. I want to use on my stock 68 Barracuda but afraid there is not enough lug nut to lug engagement. Seems like these things would come loose. Also these are the drilled 5X4 bolt Cragar.

Thoughts or experience with this?

I've ran crager SS wheels on my 69 swinger for a long time and you need to use the special lug nuts that counter sink into the wheel itself. Don't think over the years I can remember any long studs on a 4" bolt pattern rear end as at that point we would upgrade to a larger bolt pattern as well as other axel's. Maybe something like summer brothers etc. Never had a problem with the correct lug nuts that were supposed/supplied to use with the cragers. Not familiar with the 61C part ?? Probably a manufacturer number ??
Also you say these are the drilled 5x4 bolt circle. Not sure what you mean by that. Did someone drill them or the manufacturer ??
I can post a picture of the specific lug nuts later if needed.

Good luck

These wheels aren’t unilug as we are used to in the past. I’ve had too many issues over the years with them coming loose, even after being torqued to spec. Cragar manufacturer now supplies non unilug, drilled versions. Round whole, not egged.
Yes. Could you please post a picture of that lug nut when time permits.

i believe those lug nuts are the "bulge seat" style, similar to what is used on new[er] factory aluminum wheels.
as for thread engagement, i like to see at least 1 1/2 times the stud diameter. so for the factory size of 7/16, [.437] it would be .655. a little more wouldn't hurt, but with a closed end lug nut, you need to be sure the nut has enough thread, and is deep enough internally, so as to not bottom out on the stud before being properly torqued.
when i have doubts on something like this, [even after measuring the internal thread depth] i get an extra nut and trim the end off on the lathe, or drill through the end of the nut with a drill slightly smaller than the thread, thereby being able to see just exactly how much thread engagement i have.

Basic engineering standard for steel thread to steel thread is 1 to 1. Half inch (1/2") bolt/stud to half inch (1/2") nut you have to have 1/2" of thread engagement MINIMUM

I like Moparx's 1 and 1/2 times the diameter also.

1 to 1 is the minimum for steel bolt/stud to steel thread (nut)

2 to 1 for steel bolt into aluminum thread.

3 to 1 for steel into magnesium thread.

The lug nuts come with a specific washer that must be used along with the nut.
Heard that they are on backorder at the moment. Hope this helps.

Unilugs use a cam shaped washer, not the same washer as B10 is talking about.

That style of lug nut you have to also watch to make sure the lug nut when fully installed does not stick out past the wheel on the backside. Most mag wheels are thick enough, but worth looking at.

Lug nuts with the shoulders should not poke thru the other side of the wheel..check the length.