Sump studs size and thread

[Parazine]

+1 on Helicoils. Available at reasonable cost these days from ReCoil:

Recoil® | Wire Thread Inserts & Thread Repair Kits (recoilshop.net)

[Howard Wright]

Hi 

+1 from me.

Make sure you seal the helicoil in with Loctite as well as the sump bolt.  A few of the stud holes are not blind and oil finds its way down the threads.

Cheers

Howard

[Austin in the Shed]

My advice is if you have the engine out and working on the sump is if the first couple of threads are pulled,or the bolt is a bit loose in the thread when checking is just fit a thread insert. It's much easier than trying to do it in situ.
The worst situation is when someone has previously tried to drill out a broken bolt and the hole has run and or been bodged.

[Ruairidh Dunford]

I use large quantities of stepped studs and helicoils, every year.

Both work equally well, if fitted correctly, in my experience.

[dickie65]

My experience of helicoils for the sump is you need to use a Helicoil plug tap to stop the inserts being threaded into a tapered thread as left by the normal taper tap. This is due to the holes in the crankcase being quite shallow.
A plug tap or bottom tap can be made by getting another tapered Helicoil tap and shortening it without overheating it.
I am sure others have views on this.

[Austin in the Shed]

You can use an m8 plug tap.

[Steve Jones]

Firstly, Helicoils used correctly every time. I've used them for years in all sorts of applications and they do exactly what they designed to do. Re-Coil kits are not expensive and you only, really, need five sizes at most to treat most things on a Seven. However, after that (and I'm sure I might get the wrath of some) but I don't use the traditional sump set screws any more. 1/4" BSW double ended studs, Loctited into the crankcase (with Helicoils if needed), steel washers and a 1/4" BSW Nyloc nuts are now my method of choice. Coupled with a silicone sump gasket, leaks from the sump area are a now thing of the past and the sump is easily removable (although why you'd want to is a subject for another thread ) and re-fitted.

Steve

[Charles P]

 Coupled with a silicone sump gasket, leaks from the sump area are a now thing of the past and the sump is easily removable (although why you'd want to is a subject for another thread ) and re-fitted.

Steve

I do the same Steve, but my one suggested modification is that with an alloy sump it’s best to shave 1/8th off both front flange corners. If you don’t then removing the sump with the engine in the car may become difficult, as I found when I needed to do this in the Wiscombe paddock between first and second practice 

Charles

[Alan]

Ah, youth and enthusiasm, I’d have gone home.

[John Mason]

I have decided to go along the route of oversized bolts as there are only two threads too repair and I intend to do the job with the engine in the car. I will be using a silicone gasket. As to youthful enthusiasm that’s how the threads were stripped in the first place. My son is to strong for a light job.

John Mason.