richyo
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 posted on 6/6/06 at 01:15 PM |
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NPT Tap
I managed to drop my inlet manifold and snapped the water inlet pipe (X-flow engine). I believe its 3/8 NPT thread but am unsure as to what type of
tap to get. A quick look on the net made me even more confused.
Can anyone confirm that a 3/8 NPT tap is what is required ?
Cheers
Richyo
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David Jenkins
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| posted on 6/6/06 at 01:24 PM |
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It's probably 1/4" or even 1/8" NPT - it goes on the bore size, not the outside dia.
I had a similar problem ages ago - are you trying to get the old one out? They do tend to corrode and seal themselves in. I just kept drilling bigger
and bigger holes until I reached the base diameter of the thread (the narrow bit!). I could then pick out the remaining bits with a sharp pointed
hook.
I think I got a replacement fitting from Burton Power. Worth talking to them, as they know these
engines back-to-front (and the normal way round, too)
David
[Edited on 6/6/06 by David Jenkins]
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nitram38
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| posted on 6/6/06 at 01:48 PM |
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A little tip for removing broken steel studs/pipes from aluminium.
Use a mig to build up a nice weld on the top of the stud, then weld a short bar to the weld at 90-45 degrees.
The heat from the weld and the bar angle should enable you to unscrew it.
Rock the bar back and forth a few times to free up the thread. If it breaks off, just weld again. It will come out.
Never use easi-outs. They always break and then they are un-drillable.
I have used the weld method for years and never failed to remove steel from aluminium.
[Edited on 6/6/2006 by nitram38]
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viatron
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| posted on 6/6/06 at 02:48 PM |
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Is it a standard manifold? ie GGAV carb? or twin sidedraughts?
Mac
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David Jenkins
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| posted on 6/6/06 at 03:13 PM |
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Another way of getting rid of the old steel connector is to soak the area in a solution of boric acid (although it's an acid, it's not
dangerous - it's considered about as risky as table salt). It's available in chemists, especially the old-fashioned ones (it used to be a
treatment for minor wounds and burns).
It rusts away the steel but leaves the aluminium untouched - also a good technique for getting broken taps out of brass or aluminium items. Bit of a
slow process though...
David
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richyo
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| posted on 6/6/06 at 03:22 PM |
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Thanks for the replies guys
Its a standard inlet manifold for a DGV Weber
I'll try the drilling and picking first as I can't weld and don't have a welder
Richyo
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David Jenkins
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| posted on 6/6/06 at 03:32 PM |
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Just go up in small size increments, and take your time.
You could also try heating the manifold with a torch, to see if that helps to free it up - but not too hot, as aluminium melts without warning! Rub a
bit of soap or washing-up liquid near where you're heating the piece - if the soap turns black, you've heated it up as far as you can
safely.
Once the insert starts to move it'll come away easily, due to its tapered shape.
David
[Edited on 6/6/06 by David Jenkins]
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Hellfire
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| posted on 6/6/06 at 05:44 PM |
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If you have a problem getting hold of an NPT Tap... a 3/8" BSPTr taper is the same nominal size as an 3/8" NPT all the differences are in
the thread nomeclature ie thread angle, effective diameter and top and bottom radii/flat. Nothing a bit of PTFE tape won't solve. Hope this
helps...
Steve
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