Vacuum Advance?

Post by **Hellfish** » Mon Oct 05, 2009 9:27 pm

We finally got my wife's '58 Minor 1000 with a 948cc on the road and I've been going over the Haynes manual to make sure we haven't missed anything. I noticed that the vacuum advance line is pinched off (and the remainer removed). The car seems to be running fine, but she's only taken it on short drives around the neighborhood so far.

The car was previously owned by a guy who owned and raced British cars, so I *assume* he knew what he was doing and it was probably unhooked for a reason, so I'm hesitant to reconnect it. If I did, where would I connect it? Usually vac advance lines go to the carb, but I don't see where on the SU. What size is the line? What size are the connectors? If BSW I may not be able to find them over here anyway.

Post by **bmcecosse** » Mon Oct 05, 2009 10:38 pm

You should have it connected - and yes - it needs to go to a point in the inlet manifold - sometimes a suitable connection is provided on the carb - just after the throttle plate. Chances are however that the advance unit is no longer working - they only last 10/15 years. New ones are available. To test - you need to suck on the line going to the dizzy - you should be able to pull a vacuum - and you should see the baseplate in the dizzy move round - and spring back again when you release the vacuum. If you can suck air - or the plate doesn't move - new vacuum unit required. It pulls up the ignition timing immediately after the engine starts - so it allows for very littl;e static advance - which makes for easy starting. It is also an economy device - pulling up the timing on light throttle for best running on a weak mixture. Obviously the engine runs without it - but will be all the better for it to be connected - and working!

Post by **Hellfish** » Tue Oct 06, 2009 5:19 am

OK, that makes sense. It seems to run and drive just fine, but is a little rough starting and is a bit fumey (lots of reasons for that).

As you can see, there's no line to suck on, but I might be able to rig something up.

Post by **bmcecosse** » Tue Oct 06, 2009 7:15 am

Early dizzy - later type have just a push-on rubber/plastic pipe connection. You also have a later HS2 carb on there - the push-on vacuum connectioon is just visible in your picture - just above the float bowl screw at 10 o'clock. If it's lying open - it won't be helping matters either! Don't too much of your 'Race' PO so far! Non-standard fuel pump visible behind - doubt it will have a filter!

Post by **Hellfish** » Tue Oct 06, 2009 4:08 pm

I bought an inline filter, so I guess I'll be installing that tonight! Who knows what crud lurks in that gas tank!

Is there a problem with using the early dizzy? I think we have 1-2 spares, but they probably need to be rebuilt.

The PO raced Sprites, I think, and picked up this car for parts, then decided he liked it too much to part out, so he kept it on the farm and occassionally drove it around, but on the farm only. He probably did just enough to get it running for that. He passed away and his son sold the Minor to my wife.

Post by **MarkyB** » Tue Oct 06, 2009 6:01 pm

Well worth getting this sorted.
The car may seem to run OK but it will be much perkier with the vacuum advance working properly.

Post by **bmcecosse** » Tue Oct 06, 2009 11:19 pm

You can get a new vacuum advance unit - if that one is 'past it's best' !

Post by **Hellfish** » Wed Oct 07, 2009 3:35 pm

I think it's way past. I hooked up a line last night and sucked on it as suggested. It didn't budge. As Roy pointed out, I have an early dizzy and a later carb, so the 2 connections aren't exactly compatible. I had some left over plastic 1/8 oil sender line and connected it to the vac adv unit and temporarily connected the other end to the push-on connector at the carb with some shrink wrap. When we finally got the car started (whole other starter problem!) it ran poorly. Very poorly. The motor was shaking and sputtering, an smoke started coming out of the breather in the valve cover (didn't do that before - it's not connected to anything either

). At first I thought that it was the choke, but adjusting that didn't do much. My guess is that the previous owner disconnected the unit because it wasn't working, and then tuned the carb to run without it. It definitely runs a LOT better when it's not hooked up. Any thoughts?

Post by **MarkyB** » Wed Oct 07, 2009 6:27 pm

To get the engine to run OK with nothing in the vacuum tube would mean richening the mixture up a LOT.
Block the vacuum connector with something then turn the jet adjusting nut clockwise (up) to weaken of the mixture again till the engine runs properly.

Post by **bmcecosse** » Wed Oct 07, 2009 9:49 pm

As above - it's obviously been set to run with that extar air leak built-in! This is the vacuum unit you need - http://www.minispares.com/Product.aspx? ... 20UNIT%202... Note - Minispares may not be the lowest cost supplier - I just picked it because it shows the correct picture - and it IS the correct item!