OK, this is an obscure one, be warned... I was cleaning the engine on the '92 classic yesterday trying to see where my various oil leaks are, and while scrubbing I saw a disintegrated vacuum line fitting. It was the vacuum line coming off the vacuum advance unit on the differentiator. Trick is.... the vacuum line ran across the motor to a "T" fitting (also shredded) which branched off to... the thermostat?? There are TWO vacuum nipples on my thermostat, neither of which has been hooked up in God knows how long (the rubber fitment was split which made it LOOKED connected when it wasn't. From the "T", the vacuum line goes into the LH wing. People on the MiniFinity (UK) forums are telling me it's part of the emissions control back form when my car was a SPI engine (I tihnk - there's evidence the motor was converted to a single carb from SPI) - they say the line runs to a charcoal cannister in the wing, and if I now have a normally aspirated car I can disconnect all but the vacuum advance on the dizzy. Trick is, there's NO WAY there was any vacuum pressure in that line for, again, God knows how long and the dizzy seemed to work fine, plus if the line's connected to something in the WING and not off the engine how am I getting vacuum pressure for the dizzy advance? It's very odd... To top it off, I can't find a thermostat detailed in the Haynes Book of Lies that has any sort of vacuum nipples on it, so I can't tell if I need the "T" fitting or if I can delete it, nor what it does or if I should cap the nipples or even replace the thermostat housing with something without holes in it. Can anyone help?
My experience says a vacuum diaphragm from a distributor would go to a port on an inlet manifold. Without that you are going to get very little if any vacuum advance & that will result in a car that is missing a lot of its performance. You are going to have to figure out what parts are from the old EFI setup & pitch them far, far away.
Yeah, that WOULD make a lot more sense... I'm surprised the thing runs AT ALL. Is there a diagram somewhere in the B.O.L that outlines where I SHOULD connect the vacuum advance on the dizzy? There's literally nothing I can find in the Haynes book other than "you need to inspect the vacuum system". Ah, Haynes... you rascal! PS - found this thing on MiniSpares - this seems right as I have a '92 originally... Can't tell what this doohickey DOES though: http://www.minispares.com/Product.aspx?ty=pb&pid=32783&title=
Hey... is THIS where I need to hook the vacuum advance line for the dizzy? I found this broken-off vacuum line fitting underneath the air filter plastic housing, on the top of the carb: I pulled the rubber bit off and found this nipple - definitely looks like a vacuum fitting to me: As per the MiniFinity UK forums, if I'm running a carb (as opposed to SPI), all I should need hooked up is the vacuum advance for the distributor. I can't find anything on the actual inlet manifold that looks like a vacuum fitting, but it APPEARS as of this might be it. Thoughts?
Sweet! I wonder how much performance I've been missing all these years? I'm 98% certain that line's NEVER been connected properly...
You may not find any improvement after you hook it up, as it works in conjunction with the centrifical advance in the dizzy. They may have set the initial timing far enough ahead to compensate.... Also, the SPI may require a different curve (for emissions reasons mostly) that hooking it up may decrease performance, or cause it to run "funny". That could be why the vacuum post was plugged. The best thing to do is put a timing lite on it and see where it's at now, then find out how much it should have - both initial and total, and see how it compares now, then you'll know where to go from there.
It wasn't plugged, it was just hooked to what looks like part of the old SPI emissions system. Will hook it up and see if the car performs/feels any different.
i know that little vac line did a number on me...i was leaving my complex one afternoon and the rubber 90 deg connector for that vac line fell apart and it turned the engine into a sputtering mess...its amazing how one vacuum line could cause the sucker to freak out like that
What's weird is that my car has always run perfectly well without it... Always starts right up, idles fine, etc. People have said that my engine feels a bit underpowered for a 1275, but I just figured it was just... the way it was. UPDATE: I hooked the unit up this morning and the car started right up and SEEMED to have a bit more pep. Of course, after about a mile I melted straight through the vacuum line (neglected to zip-tie it away form the block... doh!) so I didn't have a proper test, but I'll drive it at lunch and report back. One of the UK guys suggested sucking on the line to check the vacuum advance on the dizzy - if the diaphragm is hosed (which might be why the previous owner connected it up the way he did) I'll be able to keep sucking air through the hose, indicating the advance needs to be replaced. It's possible, I'm told, that the vacuum advance might have failed and the old owner adjusted the idle, mixture and/or timing to "work around" it... I'll check the vacuum later today.
Funny you should mention that Matt. That is a memory I have of Eric. When ever he was done rebuilding a distributor he'd suck on it to make the vacuum advance move. I always laughed at the sight of that. Heck still do..... :lol:
Dude, if that's your thing, there ARE special web sites... :blush2: Drove it a few miles and it seemed fine - still idling great and seems to pull a bit harder (wishful thinking? possible...) I have the bonnet open to cool things off before I start sticking my hand in to disconnect that vacuum line on the carb for the "suck test".
Glad it seems to run better. I've been thinking that the vacuum lines running to the thermostat hosing may have been for some sort of temp sensor. Until the coolant got to the magic temp no advance. Just a SWAG on my part.
According to some of the UK guys, all that's needed is a straight connection from the intake to the vac advance unit. Anything else beyond that is late-model emissions control and only goes to a charcoal filter in the wing. Not sure WHY the thermostat is in need of emissions control but... (shrug). FYI - here's the part on the thermo housing - not sure what it's FOR, but this is definitely it: Mini Spares - Product - MAQ10002 - SWITCH THERMOSTATIC VACUUM FITS IN THERMASTAT HOUSING It IS listed as a thermostatic "switch" so maybe you're right... But if I connect straight from the carb to the advance, I'll get vacuum advance 100% of the time, yes?
Yes by all mean bypass that strange deal on the thermostat housing. Going from that port on the base of the carb to the vacuum advance on the distributor is how I would do it. I was just wondering out loud what the heck it was. ut: :crazy: Running a car hot does help its emissions. Used to be that a 160 or a 180 degree thermostat was the rule. Not anymore with modern engines.
I was just gonna pull it off the next time I flush the coolant. The last owner also did the "gob of silicone in place of a proper thermostat housing gasket" trick, and I was going to put a proper gasket on. While I've got it off I was going to delete the switch if I can - if not, I'll just replace the housing with a simple one.
The thermo switch should just be a pipe threaded fitting, so an appropriate brass pipe plug with some teflon tape on the threads should do the trick to replace it. If you take your dist cap off while you draw on the vacuum line you should see the points plate move, if so the vacuum advance mechanism is working correctly. No, you won't have vacuum advance "all the time", only when you have vacuum, and the movement of the advance plate is proportional to the amount of vacuum. So under hard throttle (little to no vacuum), you'll have less advance than when you're at light load, small throttle opening, high vacuum conditions - unless what you have is a vacuum retard distributor. I don't know if Mini used those, but a lot of mfr's did in the early emissions days....some used both vacuum advance and retard - those had two nipples on the advance mechanism, one on the front and one on the back, and the vacuum signals came from different sources. Again, I don't know if Mini used those or not. When you draw on the pipe note which way the plate moves - if it's the same direction as the rotor turns, it's a retard type, if opposite of rotor direction, it's an advance type.
If you ever drove a car with vacuum wipers you would understand how vacuum works. Man those things were something. :crazy:
When you shifted gears they would almost fly of the windshield and then stop as soon as you accelerated again....I don't miss them:frown2: