Triumph 1300 exhaust manifold studs

[jagnut66]

My 1300 engines exhaust manifold didn't come with any studs fitted to connect it to the exhaust front pipe.

No problem, I'll just order some new ones along with a few other bits and bobs.

The new studs arrived, I'd ordered 4, as I had one missing from the 1200 manifold, so I thought I'd fix that whilst I was at it. 

The 1200 manifold accepted it's new stud, along with some thread lock, no problem. I will do a trial 'tightening' of a 'fixing' onto it to make sure it holds and if not I'll replace the Loctite with JB Weld (if anything the hole felt a little 'enlarged').

Onto the 1300 exhaust manifold and guess what,,,

My new studs are too big for the threaded holes in it(!?!).

My replacements were listed as being correct for this application, so I was at a bit of a loss.

However, I wasn't going to let this slow the project down, so, having first checked they matched up with the size of the holes in my new front pipe's flange, out came the drill and the Imperial tap and die set.

NF24 at 5/16" is the studs thread size, the holes in the manifold required enlarging with a 7mm drill bit first, then I re-tapped them. The studs wound in nicely on the first go, again with some thread lock for good measure.

Job done.

Which just leaves me wondering why they were the wrong size in the first place......

Best wishes,

Mike.

Edited June 1, 2023 by jagnut66

[Josef]

Maybe you were filling out the nearly invisible remains of some old studs? Regardless, easier having some metal to drill out than a giant hole from stripped out threads!

[jagnut66]

15 minutes ago, Josef said:

easier having some metal to drill out than a giant hole from stripped out threads!

Good point.

I couldn't see any evidence that there was any 'remains' in the holes though, they looked clean but that isn't to say they weren't 'prepared for sale' by the seller I bought it from. 

In truth, who knows. I just wanted to see if someone else had come up against this problem.

Best wishes,

Mike.

[johny]

One thing for reference, I dont think either thread lock or JB Weld will withstand the temperature of an exhaust manifold for very long....

[Peter Truman]

I've Helicoiled them in the past to get a good thread, recently on a Spit 1500 twin exhaust manifold.

[Gary Flinn]

That's a good idea with the Brass Nuts, they should come off ok if you ever need to change the exhaust downpipe🙂

Gary 

[jagnut66]

10 hours ago, Gary Flinn said:

That's a good idea with the Brass Nuts

Thanks.

I've always used them, originally where the exhaust and inlet manifolds bolt onto the head but also, in recent years, for front pipe joints as well.

As we all know, steel nuts simply rust and / or seize on, which can lead to the air turning blue.........

I will still fit washers as well.

Best wishes,

Mike.

Edited June 2, 2023 by jagnut66

[jagnut66]

13 hours ago, johny said:

One thing for reference, I dont think either thread lock or JB Weld will withstand the temperature of an exhaust manifold for very long....

Hopefully it's unnecessary with the freshly drilled and tapped 1300 manifold anyway, just a little bit of 'belt and braces' on my part. 

My concern will most likely be the 1200 manifold, where the stud was missing in the first place and the hole is a little on the large side. Thread lock is in use at present but this is the one where I was anticipating resorting to JB Weld on. So any alternative (heat resistant) recommendations will be welcome.

Best wishes,

Mike.

 

[johny]

Well JB weld is about as good as youre going to get with heat but an exhaust manifold is asking a lot....

[jagnut66]

On 02/06/2023 at 07:40, Peter Truman said:

I've Helicoiled them in the past to get a good thread, recently on a Spit 1500 twin exhaust manifold.

Just in case, can you recommend a good kit for this?

Best wishes,

Mike.

[Colin Lindsay]

On 02/06/2023 at 20:23, jagnut66 said:

Hopefully it's unnecessary with the freshly drilled and tapped 1300 manifold anyway, just a little bit of 'belt and braces' on my part. 

My concern will most likely be the 1200 manifold, where the stud was missing in the first place and the hole is a little on the large side. Thread lock is in use at present but this is the one where I was anticipating resorting to JB Weld on. So any alternative (heat resistant) recommendations will be welcome.

Best wishes,

Mike.

 

Put a bolt through it. I always regarded it as a bodge until needs must with my 13/60, one of the manifold threads was getting tenuous and no amount of tapping would restore it to my satisfaction. I just bought a set of bolts, same thread as the studs, screwed one down through the manifold, then fitted brass nuts on the end. The bolt head will hold it in the manifold and the nuts will screw off down below allowing the exhaust to drop off, if ever required. So far, so good.

I also bought uprated studs off eBay, those sold by other 'reputable' retailers just collapsed when any kind of force was used on the nuts, and together with good phosphor bronze nuts things went together superbly.