VX 1600 Weber DCOE carb to manifold mounting

[andi4eyes]

On my ex Grads VX1600 car the Webers are attached to the inlet manifold using studs that use nuts on both ends. When I look for images and for parts online I can only find studs with UNC threads on one end and UNF threads on the other end to thread straight into a tapped manifold (I assume). No need for a nut on the manifold side.

Did the manifolds on the VX1600 come with threaded holes on the carb side? If so mine was potentially drilled out.

I am currently a thousand kilometers from my car and won't be back for a month so I can't check if my studs are the UNF/UNC kind.

Reason I'm asking is that one stud was replaced with a counter sunk(!) bolt. I assume that happened when a stud went missing and no correct part was at hand. I would like to correct that as soon as I'm back with the car.

[OldAndrewE]

I have no experience of the Vauxhall engines but all the aluminium manifolds I have ever come across have had studs threaded in the manifold (UNC).  I can see no need for a studs with nuts on either end and would have thought that without a tapped hole a suitable length UNF bolt would be a better option

The other possibility is that you do have tapped holes in the manifold and the nuts are on the protruding stud to lock it in place.  The one bolt may have a stripped thread

[andi4eyes]

Thank you for your reply Andrew.

The other possibility is that you do have tapped holes in the manifold and the nuts are on the protruding stud to lock it in place.  The one bolt may have a stripped thread

That is a possibility. It will probably remain a mystery until I'm back at the car to pull one of those studs and that bolt.

[Baggiebird]

I had a 1600 cc live axled Vx as my first Caterham back in 2001.  The holes for studs in the manifold were certainly not tapped. I know because I fitted some new rubber isolation rings during my ownership.

Something unusual that happened to me was a loose air filter mounting nut/washer which the engine somehow managed to ingest and it led to a bent valve, new pistons and head work.  I enjoyed doing it but wished that my use of threadlock and locking nuts had been more focussed!

The tale (and one about a broken engine mounting bolt in France) is somewhere in the blatchat archives no doubt!

[andi4eyes]

Thanks for your reply Baggiebird.

I will keep the air filter mounting hardware in mind and will apply some threadlock next time I'm with the car.

You don't remember the dimensions of the studs I assume?