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The thread thread

Submitted by paul_standeven on Thu, 30/06/2016
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Heavy Twins

On a Dominator timing cover, there is a threaded hole below the oil pressure relief valve. It was originally for a feed pipe to an oil pressure gauge in the petrol tank. I need to know what thread this threaded hole is.

Also, as an aside, are the open type registration plate brackets as used on bolt-up featherbed frames (1951-54) available?

Paul

Submitted by ian_richtsteig on Fri, 01/07/2016

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Paul,

Usually whitworth unless modified by someone.

Yes, sorry chaps!! I only checked one timing cover quickly and it was helicoiled to 5/16 whit. I checked several others yesterday and they were all 5/16 BSF

Submitted by ian_cordes on Fri, 01/07/2016

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I am pretty sure it is the same as the thread in the cylinder head oil feed holes. Try one of the banjo bolts in it.

Submitted by phil_hannam on Fri, 01/07/2016

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On a Dominator timing cover, there is a threaded hole below the oil pressure relief valve. It was originally for a feed pipe to an oil pressure gauge in the petrol tank. I need to know what thread this threaded hole is.

Try 5/16" BSF......... as noted by others...same as the top rocker feed banjo bolts. Avaialable from RGM, Norvil, A/Norton etc at about £5 each.

P/N 067696

Norton-Commando-Dominator-Rocker-Oil-Feed-Pipe-Banjo-Bolt-5-16-06-7696-UK-MADE

Submitted by paul_standeven on Sun, 03/07/2016

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Yes, it's a 5/16" BSF thread. I tried the rocker oil feed, a known BSF stud and a bolt. Since the bike uses mostly Whitworth or BSC, it's odd to use BSF here. It must be a standard item adopted.

Paul

Submitted by phil_hannam on Mon, 04/07/2016

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Threaded Holes - Aluminium Heavy Twin Heads.

All threaded holesare Whitworth form (with 55 degree thread angle).

Dominator, Atlas & Commando - forthe 3 head/barrel studs - 3/8 BSF x 20tpi

Atlas - headsteady centre stud hole - 3/8 BSF x 20tpi

Dominator, Atlas & Commando - intake rocker cover stud hole - 5/16 BSF x 22tpi Dominator, Atlas- 2 oil inlet on top of head - 5/16 BSF thread x 22tpi Commando - 2 oil holes on side of head + 3 headsteady bolts -5/16 BSF x 22tpi Dominator, intake port manifold - 1/4 BSW x 20tpi

650, Atlas and Commando-intake port/manifold - 5/16 BSW x 18tpi Dominator, Atlas & Commando- rocker spindle cover plate screws (pre 66-short) - 1/4BSWx 20tpi

Dominator, Atlas & Commando- exhaust rocker cover studs- 1/4 BSW x 20tpi

 


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