1970 Hood / Wiper Grille Screw Size ?

[Juliet P.]

I received this e-mail from a '70 Registry member but don't know the answer. Can someone please help? He's unable to post to the board due to technical issues. Thanks, ~Juliet

Wondered if you can tell me something or if you know who knows. You know on a 70 coupe there is the grill that goes from side to side at the back edge of the hood just in front of the windshield wiper door. It is held on with 6 screws. Do you know the thread size? I want to retape the threaded area below that these screws thread into and have not been able to find that. I expect it is a 10 32 or 10 24 or something like that, just want to be sure I use the correct size tap. Don't know if the orginal screws are sitting in a mass of screws I have or where they are.




1970 Corvette Registry

[David N.]

Re: 1970 Hood / Wiper Grille Screw Size ?

Juliet,

My 1969 uses 8 phillips head machine screws #8X32- 3/4 inch long. I have also cleaned up the threaded holes with said #8X32 tap with cutting oil applied to prevent breakage. I suggest that if the tap meets more resistance than expected, that you back the tap out a half to full turn or two then continue turning in the tap just like cutting new threads in an unthread hole.

Member 19639
David Nims

[Juliet P.]

Thank you. *NM*

[Jim T.]

Re: 1970 Hood / Wiper Grille Screw Size ?

Juliet the 6 screws you mentioned are not just run of the mill type Phillips. The head of these screws is different for most Phillips head screws.

[Terry M.]

Re: 1970 Hood / Wiper Grille Screw Size ? *TL*

I guess I am going to have to look, but I thought they were fillister head phillips screws, but I am working off the top of my head, and I shouldn't do that.
BTW: Be very careful in chasing the threads. If you break the tap off in there you are in deep trouble. Use lots of lubricant - that is an aluminum based casting and mineral spirits is one acceptable lubricant. Oil is not the best cutting fluid for aluminum. Go slow and back the tap out often.

[Jack H.]

Holding....

my 'backup' set of correct/original cowl grille screws and comparing with a set of 'correct/reproduction' grille screws. Interesting....

The originals are 5/8-inch in length, 10-32 with Phillister hex head, black oxide finish and THREAD CUTTING tips. The reproductions are 3/4-inch long, 10-32, black oxide WITHOUT the thread cutting tip feature.

Might explain why underlying grille mounting holes tend to get wallowed out.... If in a hurry to re-install and you cross thread a thread cutting fastener in an already threaded hole, one can 'chew' out the hole's existing tap.