Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Vacuum tube and where to put it.

I have a 1982 4/4 1600 with a cross flow Kent engine. Foam air filter in place of the massive cast unit.

I would like to know if anyone knows the correct place to plumb in the distributor vacuum. I have had a few running issues recently (revs drop when hot, unstable idle etc) and I am making sure everything is plumbed in correctly. I may have completely botched it up when taking the original air housing off. I am used to British bikes!!!

I think there are two places it could go, one is a tube coming out directly underneath the autochoke, the other is a strange coupling that comes out of the manifold, just below the flange where the carb meets it. This second outlet has a junction, one tube goes to a plastic box attached on the side of the engine and the other was hanging free!

Have I connected the correct outlet to the vacuum, or is there a better choice?

Just to follow up, I have added a photo and the top tube is the one the vacuum is currently connected to, and the one just below it with a kink at the top is the second one I was referring to to.

Can't really tell from your photo, but...

The vacuum tube is a small bore tube that starts on the inlet manifold and goes to the can on the side of the distributor.

With that understood, you ought to get it right. Certainly should be no kinks in it.

from the sound of it rather than the photo, the lower one probably. It should come direct from the manifold (it'll have some 'suck' when running) . never saw one that came off the carb body. Martyn's right... no kinks or it won't work!

You can probably just make it out from here. Seems the plug you're currently connecting too is blanked off on mine....

My vacuum line as a fitting directly to the carb.

The connection at the carbs has been blanked off on mine since I've had it. Never had a vacuum tube connected and never had a problem.

~iw

The unstable idle should be nothing to do with the vacuum advance, or the lack of it, should it?

If it is sucking some air through a faulty tube or connection it may have an effect.

First off, I've no idea specific knowledge of Kent engines.
However; two distinctly types of vacuum connections exist, ported connections and [you guessed it] non-ported and they exhibit totally different characteristics.
A ported take off will be adjacent to the inlet butterfly on one of the carbs/chokes; at very small throttle openings the velocity of the passing air is relatively high - hence - it pulls a disprortionally high vacuum, at mid opening the air speed drops hence the vacuum will drop.
Non-ported is taken off a 'mid point' somewhere on the inlet block, regard it as an averaged vacuum, it doesn't respond so peakily to small openings but equally doesn't fade on mid steady state openings. Non-ported take offs are used by some distributor vacuum units, they are also used to provide the vacuum to servo brakes.
Which one a Kent engine, or your version of the engine / distributor needs will be down to the workshop manual.
As a thought - your alignment of the various tubes maybe perfectly correct, a more likely cause of the problem may well be the vacuum unit itself, after 45+ years of a hot petrol/air mixture the rubber diaphragm will probably have died.
My suggestion would be to try sucking against the vacuum unit to see whether the base plate on the distributor actually moves or not.
If you are going to get a replacement unit, they are not universal, go to [say] Burtons or someone who knows Kent engines as different years, models and spec of engine will have had different distributor spec's and different vacuum spec's.

Gents, sorry for not saying thank you sooner, but I have been beavering away at work and not been able to get to my computer. So thanks for the advice and I will give it some thought and attention this weekend.