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I’m trying to find a set of ‘73-‘76 hood grille nuts (GM part no. 9420621) NOS or good used. They have rubber cushion inserts on the underside. I haven’t come across any repros and the replacements sold by the usual suppliers are acorn nuts that look nothing like the correct part. Here’s what the originals look like:
That’s where I got the photo. Two concerns: the one example shown is pretty rough-looking and it wasn’t clear whether there was more than one for sale. I’d like to find a set without the rust. Thanks for trying to help.
Very close. They are described as “thread cutting” and are to be used with “smooth studs”. I’ll take a look at the studs on my hood and see if the threads on them appear to have been cut by the nuts when they were installed. If they are a standard thread — say 3/16-20 — then these nuts might not work. But I’m betting they will. Thanks for finding these, and thanks for introducing the term “thread-cutting nuts” to my vocabulary.
Very close. They are described as “thread cutting” and are to be used with “smooth studs”. I’ll take a look at the studs on my hood and see if the threads on them appear to have been cut by the nuts when they were installed. If they are a standard thread — say 3/16-20 — then these nuts might not work. But I’m betting they will. Thanks for finding these, and thanks for introducing the term “thread-cutting nuts” to my vocabulary.
A trick I learned is to set the nut over the stud, then turn it counterclockwise (lefty) slowly applying slight pressure. You will feel a click. This is the threads lining up with the nut. Slowly start to tighten. If there is little resistance, you’re following the existing cut threads. If not, you’re cutting new ones.
A trick I learned is to set the nut over the stud, then turn it counterclockwise (lefty) slowly applying slight pressure. You will feel a click. This is the threads lining up with the nut. Slowly start to tighten. If there is little resistance, you’re following the existing cut threads. If not, you’re cutting new ones.
I’m not an authority (NCRS judges feel free to weigh in here), but I believe that you may lose originality points for using acorn nuts under strict judging if the thread cutters turn out to be the right part. Anybody out there have a completely untouched original ‘73-‘76 and care to comment?
I think the black stuff isn't a rubber gasket but some kind of sealer. It should call it out in the Assembly Manual.
By Jove, you are right. I went back and pulled this quote from the site linked above by n2h2o2
You are buying one (1) NEW assortment. This assortment contains forty five (45) (see sizes below) zinc plated thread cutting nuts with mastic sealer that can be used on Buick, Cadillac, Chevrolet, Oldsmobile, Pontiac & GMC vehicles.
One were original acorn nuts. I was missing one is why I ordered the set
If you are the original owner and your car has never been repainted, that’s a really helpful input. Otherwise there’s no way to know if your acorns are original without some more authoritative info. I’m not sure that this minor detail is worth anymore back-and-forth. As Bob Dylan sang, “you go your way and I’ll go mine.”
According to Section 8 "Hood and Vent Grille" on page 77 of the 2018 3rd edition NCRS 1973-1974 Corvette Technical Information Manual and Judging Guide, "Six (6) black phosphate-plated acorn nuts secure the underside of the grille". Fig. E 8.1 on the same page shows them.
According to Section 8 "Hood and Vent Grille" on page 77 of the 2018 3rd edition NCRS 1973-1974 Corvette Technical Information Manual and Judging Guide, "Six (6) black phosphate-plated acorn nuts secure the underside of the grille". Fig. E 8.1 on the same page shows them.
Fran Giacoma
Thanks, Fran. That’s an authoritative confirmation of Mikey857’s input about the acorn nuts (at least for the ‘73-‘74 model years — no reason to believe the ‘75-‘76 are any different). It seems that the original black phosphate nuts are discontinued (https://www.corvettecentral.com/c3-6...-pieces-343045) but chrome facsimiles can be had (https://www.motorcityvettes.com/exte...-set-1973-1976). Nothing a spray can can’t fix.
Hood Grille Nuts
