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[jawa-enfield]

.Inland model, don't know if that makes a difference.
I want to mount a manifold and because of the thickness of the connecting rubber there's no space for the nut, so i am searching for 2 hex-bolts with tje corresponding thread..

The nuts are non-metric.
Does anyone know which of the English-treads is used for the inlet manifold?

[Wheaters]

Another thread pattern used by RE in unexpected places was 26 tpi, British Standard Cycle thread.

A place you can check on an Indian iron Bullet is the threads in the vertical frame studs holding the rear brackets of the seat. Try the existing nuts on there to confirm if that's what they are.

[jawa-enfield]

You mean these ones?

Good tip to sort it out, am searching for days for the 4/16 BSC.. what if they are not!!
Thanks!!

[jawa-enfield]

The nut from the inlet manifold fits on this bolt!!
So i was looking for the wrong thingy all along?

[jawa-enfield]

But if i look for 26 TPI hex bolts i do not get hex bolts?
Maybe google translation is wrong, what are these kinds of bolts named in English you need an Allen-key for?

And is TPI the same as BSF?

[stinkwheel]

A hex bolt has a hexagonal head to take a spanner.

I suspect you are looking for socket head cap screws which have a hexagonal recess for an allen key.

TPI means Threads Per Inch.

26TPI is usually a British standard cycle thread -often abbreviated to BSC or BSCy. It's historical. Most of the old british motorcycle manufacturers originally made bicycles so the chassis parts tend to still use BSCy.

BSF is usually a different number of TPI but there can be some overlap between the systems. One will often screw into another one for a few turns before becoming stuck.

5/16 x 26tpi is a cycle thread.

You will REALLY struggle to find socket head cap screws with a cycle thread. I have two suggestions. One is to by some other 5/16" bolts with a different thread and a long plain section on them. You can cut off the threaded part and buy a cycle thread die to make your own fasteners.

The other is to fit M8 thread inserts to the head and use M8 fasteners.

Both options take about as much time, effort and money.

[Wheaters]

Looks like my theory was correct.

What you need are sometimes called Allen screws or bolts.

Rather than searching on the usual online auction sites you might have to try a specialist.

“https://www.custom-fasteners.co.uk/“ might be able to help but please try Hitchcock’s first, seeing as we are hosted by them.

[jawa-enfield]

Anmd TPI, is BSC and CEI?
i will look..
Yes, the translation says the thingies for an allen key are hex bolts and a hex key is the same as an allan key but that doesn't work out.

It tapping a M8 thread possible?

[Davedup]

If our hosts can't help try nookys nuts, he's really helpful

http://www.nookysnuts.com/

[stinkwheel]

Anmd TPI, is BSC and CEI?
i will look..
Yes, the translation says the thingies for an allen key are hex bolts and a hex key is the same as an allan key but that doesn't work out.

It tapping a M8 thread possible?

No TPI is how many turns of thread there are for every inch. It is a measurement of the thread pitch.

5/16" is 7.94mm so too close to drill and over-tap an M8 without making a real mess of things. So then you'd be looking at M9, which is probably just as difficult if not more difficult to obtain. If I was going for a metric conversion, I'd use an M8 timesert type thread insert where you drill the hole oversize, tap it and screw a threaded insert into the hole to take it back down to the desired size.

BSC is "British Standard Cycle Thread" which is a system of thread sizes of particular size and pitch (in the same way as you have metric course and metric fine thread sizes or Whitworth or Unified threads). CEI stands for "Cycle Engineers Institute." thread system, which is measured differently but again is a type of sizing standardisation.

Historically before there was BSC, there was chaos, each manufacturer just made their own threads and it was the case that each nut and bolt had to be kept for the particular hole it was going in on the particular machine it was fitted to. If you lost one, you'd have to make a replacement.

As I say, I have always known the type of fitting that takes an allen key as a "socket head" or "allen-head".

The "Hex" referrs to a six-sided hexagonal shape. I would usually referr to a standard hexagonal bolt head as a hex-head Another term for an allen key is a hex-key but that is referring to the tool that undoes the fitting, not the fitting itself.

Isn't English fun? Don't let the French tell you it's all about metric either. Even they use 9/16" x 20tpi threads on their bicycle pedals which is a very odd thread size first used for this by the Wright brothers (yes, those ones).