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Dumb question about vacuum advance pipe

Posted: Mon May 28, 2012 1:58 am
by Fingolfin
Lots of dumb questions from me tonight! :lol:

My question is this: how does it hook up to the carburetor? Knowing where on the carb it hooks up would be nice too, though I think I already know that (threaded hole on trailing side underneath accelerator lever). Also I'd be interested to know what route it takes through the engine bay.

I should make clear: Mog's vacuum advance pipe is sort of rubbery and flexible, and isn't the metal type. I suppose I should ask if that's normal. :roll:

Re: Dumb question about vacuum advance pipe

Posted: Mon May 28, 2012 8:34 am
by MarkyB
Is it a push fit on the distributor?
Mine is a small bore plastic tube with bits of rubber tube pushed on both ends to connect it.
On the carb end there is a small brass tube with a bulge to retain the pipe.

Re: Dumb question about vacuum advance pipe

Posted: Mon May 28, 2012 4:20 pm
by katy
Look at the pictures on the thread: "948 manifold on an 1100"

Re: Dumb question about vacuum advance pipe

Posted: Mon May 28, 2012 9:20 pm
by Fingolfin
Huh! Well that's not what I've got. Here are some photos to help illustrate what I'm on about.

The front of Mog's carburetor seems to have the spot from "948 manifold on an 1100" occupied by the accelerator levers:[frame]Image[/frame]
This is the tube, at the end:[frame]Image[/frame]
And at the start (it doesn't appear to be a push-on):[frame]Image[/frame]
This is the hole in the trailing side of the carb I thought it might go in:[frame]Image[/frame]
It seems to be similar to ESM part no. VAC101E, except without the rubber boots. I just can't see how it can connect (and get a good vacuum) with the carburetor. :roll:

Re: Dumb question about vacuum advance pipe

Posted: Mon May 28, 2012 10:01 pm
by bmcecosse
Your carb and dizzy are fitted up for the copper pipe vacuum system. It will be v difficult to adapt the plastic pipe.......

Re: Dumb question about vacuum advance pipe

Posted: Mon May 28, 2012 11:43 pm
by Fingolfin
Curious! It was fitted with the plastic pipe when I got it -- I've changed nothing here. :o I suppose I ought to order the metal one, then, or look for one on the electronic bay. ESM's part no. VAC101, the metal pipe, doesn't appear to have a screw-in connector with it, so I'm still wondering how the thing connects to the carb, and whereupon.

Re: Dumb question about vacuum advance pipe

Posted: Tue May 29, 2012 8:15 am
by mike.perry
I have H1s and a pair of H2 carbs with no vacuum pipe fittings, probably for use with a non vacuum advance distributor such as the DKYH4A

Re: Dumb question about vacuum advance pipe

Posted: Tue May 29, 2012 4:23 pm
by Fingolfin
I'm pretty sure the vacuum advance pipe was hooked up somehow. I know Mog's dizzy has got the advance system (obvious in the photo above), and the car wouldn't run terribly well without proper advancing, would it? It ran pretty well before. The trouble is I've forgotten how it went together, and for some reason I don't have a good photo of it before I took it apart.

Would it make any difference to know that this engine, gearbox, dynamo, and probably dizzy and carburetor are from an MG Midget (I think)? I can't imagine it would, but I thought I'd mention...

Re: Dumb question about vacuum advance pipe

Posted: Tue May 29, 2012 9:32 pm
by bmcecosse
You can use the plastic pipe - but you will need to get air tight connections at each end.....otherwise it will just be cosmetic..... There must have been some sort of connection into that threaded hole in the carb?

Re: Dumb question about vacuum advance pipe

Posted: Tue May 29, 2012 10:41 pm
by mike.perry
The 948 and 1098 Midgets used 2 x HS2 carbs not H2s.
My twin H2s are on a 5 port i/e manifold

Re: Dumb question about vacuum advance pipe

Posted: Sun Jun 03, 2012 4:41 pm
by Fingolfin
Well, I've got sort of a bodged solution to the problem, but I believe it will work. I had a spare metal vacuum pipe, but it had a blockage inside (couldn't blow or suck through it), so I cut off its carburetor end with an inch of pipe to spare, and connected it to the plastic pipe with some tight-fitting rubber that is apparently specifically for vacuum purposes. Here's the rubber hose; you can just see where it connects to the old metal pipe.[frame]Image[/frame]
Old photos show the vacuum pipe running under the battery box, so that's where I ran it this time. Any comments?

Re: Dumb question about vacuum advance pipe

Posted: Sun Jun 03, 2012 5:16 pm
by bmcecosse
The test is to suck from the carb end - does the dizzy baseplate move back and forth? And then of course - it just needs a good air tight connection at the carb.....