Brum exhaust manifold bolts

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Brum exhaust manifold bolts

Postby Russell » 12 Sep 2017, 19:46

Anyone know where to get exhaust manifold bolts for a '58 Brum, like these...

WP_20170912_20_13_48_Pro.jpg


Also what thread is it? so I can get a tap to clean up the holes.

One other question, the middle bolt hole is a lot shorter than the outer ones, is that normal ?
Russell
 
Posts: 65
Joined: 07 Oct 2009, 22:02
Location: West Yorkshire, UK

Re: Brum exhaust manifold bolts

Postby scott596 » 13 Sep 2017, 09:13

Russell, this is a bodge, what you should have is 3X studs in the barrel, the centre hole in the exhaust manifold has a large hole and requires a special shouldered nut for location because the outer fixings are slotted and might not centralise without this nut. I have stainless studs available but I must warn you I have come across all sorts of thread combinations for these so be wary that the wrong thread might have been forced into your barrel . Alan Noakes. scottworkshop@hotmail.co.uk
scott596
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Posts: 121
Joined: 31 May 2004, 17:01
Location: Lincolnshire

Re: Brum exhaust manifold bolts

Postby Russell » 13 Sep 2017, 09:47

It is possible that the “bolts” I have are actually studs with nuts seized on the end? The “nut” part does have a shoulder with a captive washer on it. When I bought the bike the two outer "bolts" were like this. The central one was a stainless steel stud and dome nut (no shoulder), with a different thread, that looks to have been forced on and now doesn't tighten. The central hole does look wider, but is also not as deep as the outer ones?

Cheers
Russell
Russell
 
Posts: 65
Joined: 07 Oct 2009, 22:02
Location: West Yorkshire, UK

Re: Brum exhaust manifold bolts

Postby Russell » 16 Sep 2017, 18:22

I've managed to separate the nut from the stud, so they are studs. I've tried measuring the thread of the stud, and the closest I can find is 5/16 BSCY, does that sound right?
Russell
 
Posts: 65
Joined: 07 Oct 2009, 22:02
Location: West Yorkshire, UK

Re: Brum exhaust manifold bolts

Postby scott596 » 17 Sep 2017, 08:54

Russell, one thing you learn with Scotts is that there is no right and wrong, as I said I have come accross all sorts of thread combinations, in most cases the casting will be tapped either BSF or BSCY, the studs I make have both these threads on them so you can either use a bsf nut or a bscy nut, as you know already the centre nut is special and will have to be made to suit. Alan Noakes. scottworkshop@hotmail.co.uk
scott596
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Posts: 121
Joined: 31 May 2004, 17:01
Location: Lincolnshire


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