Manifold stud thread size? 350i V8

[ferlin]

Does anybody know for sure the size of the threads on the standard V8 350i cast iron exhaust manifold studs please?
Are they 8mm x 1.25 fine threads?
I would like to buy some new nuts!

[Wedg1e]

3/8" UNC rings a bell...

[adam quantrill]

Cast manifold - do you mean like an SDi one? I didn't think these were ever fitted to wedges but I might be wrong...

Even the SDi ones have standard bolts to screw them onto the cylinder head. They would be UNC and whatever the imperial thread is that's just smaller than M10. Studs would be unusual cos I can't see the manifold coming off with the studs still on there...

[Danny Hoffman]

Very early 350is had cast iron manifolds, I've never seen studs though

[adam quantrill]

Reminds me - the tubular ones fitted to (most) 350i's must be worth a few ponies/donkeys/mules or whatever (over and above the SDi vitesse figures that is...)

[Danny Hoffman]

7 apparently

[ferlin]

yes they are cast iron like the SD1 manifolds which are bolted onto the cylinder heads so that they come off easily but the bottom flange has studs screwed into it. Quite a normal set up really. I will attack it today and try to see what threads I have.

[adam quantrill]

Ahh - the flanges - my guess there would be a standard 1/2" nut but yes try a few different ones. What do the downpipes look like on this setup - do they end up with a sleeve fit onto the centre box section?

[Danny Hoffman]

ferlin said:

yes they are cast iron like the SD1 manifolds.

I did read they used Land Rover rather than SD1 manifolds

[ferlin]

All sorted today. Nuts are 5/16 unf and were difficult to find but I managed to find some lovely double length old school brass ones in a back street garage.
Once I had sealed the front up I could hear some other little puffs. I ended up putting two new clamps on and resealing up a few joints. Sounds lovely again now!

Adam, my Exhaust system is a special because I have an auto box. I have lots of offshore grade stainless push fittings joined through the middle sections. The front right is rigid and then goes into a twin wall stainless flexi pipe on the left with a y piece. This allows the engine to move without stressing the pipework. I have a rear tail box with a home made baffle cos it was too noisy without. As I said it's a bit of a special but sounds ace

[adam quantrill]

Sounds interesting.

Are those nuts the ones with the horizontal slot cut in so they are self-locking? If not put a dab of fire putty on the exposed thread to stop them shaking loose.... I used to have that problem on my P4.

[ferlin]

they were just plain nuts without a slot but double length. Good tip with fire cement.

[Wedg1e]

adam quantrill said:

Are those nuts the ones with the horizontal slot cut in so they are self-locking?

Commonly known as 'stiff nuts'

Made by Aerotite, amongst others.

[Transmitter Man]

Wedg1e said:

3/8" UNC rings a bell...

Correct.

I just ordered Nor-Lock washer set.

Phil
420 SEAC