11/32 drill bit is what you use if you are tapping for a 3/8-16 hole. However, most heli-coil kits work by drilling and tapping to the next biggest size. The heli-coil will have that bigger size thread on its outside and the smaller thread you need on the inside. Those are how the heli-coils we use at the plant work..not sure if they are all like that.

 

The next size up? Not sure what that means.

This type heilcoil has the same pitch as the thread being repaired meaning you need special heilcoil tap with a larger diameter but the same pitch. That is why the tap comes with the inserts. That tap will define the drill size. The numbers I posted are from the heilcoil manual.


There are much heavier thread repair insert. This is a common insert used in industrial applications.
3/8-16 Inch Internal Size, 9/16-12 inch 36753580 - MSC

 

woh stainless,,, kool. an they knew who i am,,, musta bougth something from them.

 

uh oh dont leave us for hollywood now crabby lol


Please dont make me panic guys. I have the 95 LT1 and the bolt size is 3/8. I ordered a helicoil kit from amazon yesterday. Drilling a bigger hole was what i originally thought i had to do to get the OEM size bolt in, which i hope is not the case since i dont feel to comfortable doing that. Below is the link to the exact kit i bought.


https://www.amazon.com/Helicoil-5521...%2F8++HELICOIL

 

You need to drill out the hole with a 25/64" drill bit, then tap the hole, then install the insert. Don't forget to use oil when tapping. Take a deep breath, go slow, and you'll be fine.

 

I spend about $1000 a month with them on my company card. I pay about 60% of the prices you see and free shipping Honestly even with the discount they are over priced. I can find most stuff cheaper online. MSC is just so easy to use.


rs657f

Do you have access to a drill press? If you can make a tap block it would make the process less touchy.

Tons of videos on youtube

 

I wish I had a drill press and a garage at least lol thats my next goal. I received my helicoil kit in the mail. It definitely isnt the one in the link but it will work. I see the tap is way bigger to create the 3/8 thread. Ill go get the bit and give it a shot this weekend.

Thanks for all the help again guys

 

The better Heli-Coil® kits come with drill bits
R1185-6 includes X drill bit, $26 at Grainger

https://www.grainger.com/product/HEL...Query=r-1185-6

DON'T FORGET to break off the install tab at the bottom of coil after installing.

 

Thanks everette. The link didn't work but I did get my helicoil in the mail the other day.


I was reading I should use red Loctite on the coil when inserting. thoughts on that?

 

It wouldn't hurt.