Stupidly ruined a manifold - fixable?

[eltax91]

Hello all

I am restoring a Range Rover classic with the 4.2 v8. I blasted and painted the manifolds and then decided it might be a good idea to remove the studs and replace them. 2 came out no problem but a 3rd snapped flush.

I flipped it over and drilled out from the back. The stud is an m8. Without realising I wandered off centre, thought ‘no problem it’s very hard metal, I’ll drill and tap a new m8 thread, it’s forgiving enough to be a mm or two off’

Then for some stupid unknown reason I went up 0.5mm drills at a time and due to tiredness/ stupidity I drilled it out to 8mm rather than the correct tapping drill *for* 8mm.

So, is this now scrap or is there a way out? I have a plethora of tools, can weld etc. have never done a helicoil which could be an option?

Fill it with weld and then drill and tap a fresh hole?

Scrap it and cost myself a chunk out of my budget?

If you don’t have an answer, feel free to flame me for being so daft.

Edited by eltax91 on Sunday 3rd November 23:18

[Smokey Bear]

Maybe I’m missing something but is there any reason you can’t use a nut and a boot there?

[eltax91]

Smokey Bear said:

Maybe I’m missing something but is there any reason you can’t use a nut and a boot there?

Nope. You aren’t missing anything. A friend just WhatsApp’d me the very same thing. I was totally over thinking it.

Nut and bolt it is!

Edited by eltax91 on Sunday 3rd November 23:47

[hidetheelephants]

A helicoil would work assuming your hole is in the right place; the drill size for M8 is larger than 8mm.

[E-bmw]

eltax91 said:

Smokey Bear said:

Maybe I’m missing something but is there any reason you can’t use a nut and a boot there?

Nope. You aren’t missing anything. A friend just WhatsApp’d me the very same thing. I was totally over thinking it.

Nut and bolt it is!

Edited by eltax91 on Sunday 3rd November 23:47

Sometimes you just get too close to see the obvious easy answer.

[hidetheelephants]

Is there clearance for a nut and bolt? Some cast manifolds are very tight and won't take a nut and bolt without a lot of grinding and you still need to get a spanner onto it.

[eltax91]

hidetheelephants said:

Is there clearance for a nut and bolt? Some cast manifolds are very tight and won't take a nut and bolt without a lot of grinding and you still need to get a spanner onto it.

Will be checking later, but yes I think there is clearance for a socket/ extension bar

[Peanut Gallery]

If no room for a nut and bolt, how about a "keensert"? - Drill out to 11.5mm..
https://uk.rs-online.com/web/p/thread-repair-inser...

[normalbloke]

Smokey Bear said:

Maybe I’m missing something but is there any reason you can’t use a nut and a boot there?

Is that a Canadian accent I hear there…

[eltax91]

Thanks all

Nut fitted, clearance checked - can get a socket on and a spanner on. So should be ok

[donkmeister]

Tired and/or frustrated, grabbing a drill and finding one's hand-held x and y axes aren't quite up to spec. Yup, been there.

I find in such scenarios it's handy to live nextdoor to a former machinist who puts up with one's nonsense.