Helicoil for plenum

[Hannibalzero]

Does anybody know what size helicoil is needed for the 12mm plenum bolts? I've never used helicoil before, but I assume you need to know the exact thread size and pitch.

[BillyC]

Did you strip out the threads in the lower intake? The first time I changed the plugs in my TT, one of the bolts brought the threads out when I removed it. I just tapped it out to a standard size thread (5/16-18 I think). Kind of ghetto, but it works.

[Hannibalzero]

[quote=""thestealth""]Did you strip out the threads in the lower intake? The first time I changed the plugs in my TT, one of the bolts brought the threads out when I removed it. I just tapped it out to a standard size thread (5/16-18 I think). Kind of ghetto, but it works.[/quote]

Yup. I actually have several stipped plenum bolts - one in each car. I thought about tapping, but I've heard helicoil works well in this situation. I figured that would be the easier route to go.

[BillyC]

It's about the same amount of work really. You'll have to drill the hole out a little larger and then tap it for the helicoil...
The stripped hole I tapped out was the perfect size for tapping for a 5/16 bolt, so that is what I went with...plus I did'nt have a helicoil set and I had just bought the car and wanted to drive it.

[Barefoot]

I dont remember the exact size, but I once striped a bolt in my lower intake plenum over a year ago, and heli-coiled every bolt hole on the lower intake plenum. Haven't had a problem since

You do need to know the size, but you could always just take your bolt to the autoparts store that sells helicoils and match it up. the helicoil kit should come with the correct tap and drill bit.