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I noticed today that the vacuum advance hose was split, it is the very small bore type with push on 90deg. elbow ends that go from the small bore of the hose to the larger bore of the dizzy/manifold.

Now I had some silicon hose about 4 or 5 mm bore, so i put that on the manifold/dizzy.....................The dizzy instantly became noisy.............. can't get my head around why. As soon as I remove the silicon hose the noise goes, if i put the original very small bore hose back on [ now with no split ] there is no noise, silicon hose back on..... noisy again.

Is it allowing to much vacuum to the dizzy? What happens inside the dizzy to make the noise.

This is on a 2.5 pi engine with 22d6 dizzy.

    Any advise is most welcome, cheers......... Andy.

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the vac unit only rotates the contact plate a small amount to advance it mainly when cruising ,it also holds it in place
i can ony suggest you tyake the cap off and such (by mouth) the tube and see just whats moving, the close coiled spring hooked over the base plate pin  is all that connects the vac to the base plate,  there must be some wear or movement causing the moving plate to pitch and make some irrregular contact , also check is there any side play in the cam spindle ??? due to a worn base bush ????
the size of pipe or how its connected has no real bearing on how it works apart from it shouldnt leak       Pete

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Thanks Pete.

It appears to be because the vacuum at the front take off is fluctuating between 6 and 10hg at idle. See my post in Big saloon section.

If I swap to the rear take off its ok.

The smaller pipe must dampen the fluctuation.

                   Cheers --- Andy ---

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