Hi.
My vacuum advance looks pretty shabby. The car runs OK but I've always doubted it. I tried the suck test (disconnected the metal vacuum pipe assembly at the carb). It wouldn't hold a vacuum and nothing moved inside the distributor.
I've gone online to source a replacement but the end of mine is threaded to accept the metal assembly pipe. Online ones such as this seem to suggest they're for a rubber hose push on only https://www.ebay.co.uk/itm/126011556997 ... media=COPY
Is anyone able to send me a link of the correct vacuum advance replacement please for a lucas 25d?
Or, is it acceptable instead to use the vacuum advance from the link above and replace the metal assembly pipe with a rubber one (therefore without the cylinder)?
I was going to get a professional to tune the engine as I'm no expert so I'd like to have the parts ready for them.
There is no problem with using the push on vacuum advance unit. You have a push on connection at the other end at the carb.
The metal canister should be mounted vertically as it is a flame trap. The pipe to the vacuum advance unit should be at the top and the pipe to the carb at the bottom.
If you ring Distributor Doctor he can sell you a vacuum advance unit that is threaded. The diaphragm inside perishes. I have never got them to operate with a suck test but I have used a brake bleeder vacuum pump which also tells you what pressure the vacuum advance is operating at.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Yes, the trap was mounted vertically, on my engine, in a dedicated bracket secured by one of the front cylinder cover nuts.
However, I now use a plastic pipe with push on connectors at each end.
If I recall, and until the vacuum advance unit was replaced, I utilised the screw on end after cutting the pipe and pushing a rubber tube onto the end of that copper pipe.
I still use the bracket and a suitable rubber grommet to support the pastic pipe.
I must have a good suck because it moves for me without a vacuum device.
olonas wrote: ↑Sat Feb 17, 2024 11:43 am
Yes, the trap was mounted vertically, on my engine, in a dedicated bracket secured by one of the front cylinder cover nuts.
However, I now use a plastic pipe with push on connectors at each end.
If I recall, and until the vacuum advance unit was replaced, I utilised the screw on end after cutting the pipe and pushing a rubber tube onto the end of that copper pipe.
I still use the bracket and a suitable rubber grommet to support the pastic pipe.
I must have a good suck because it moves for me without a vacuum device.
I’m not too fond of the taste of oil!
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Thanks for all your replies. I've messaged the distributor doctor to ask about a threaded version. If this is much more than the powerspark vacuum advance from ebay am I right in thinking I could cut the metal pipe, say 6" up from where it joins to the vacuum advance therefore removing the threaded end. Then use a section of new rubber tube to connect the now cut metal tube to the push on vacuum advance end? That way I'd retain the flame catcher. Hope that makes sense. Thanks for your help.
The thread on the vacuum unit that connects to the metal vacuum pipe is 5/16 UNF 24 tpi. You might be able to thread it yourself if have have the correct die and the plain pipe end is a suitable size.....
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
jammmorris wrote: ↑Sat Feb 17, 2024 12:01 pm
Thanks for all your replies. I've messaged the distributor doctor to ask about a threaded version. If this is much more than the powerspark vacuum advance from ebay am I right in thinking I could cut the metal pipe, say 6" up from where it joins to the vacuum advance therefore removing the threaded end. Then use a section of new rubber tube to connect the now cut metal tube to the push on vacuum advance end? That way I'd retain the flame catcher. Hope that makes sense. Thanks for your help.
Yes, but you don't need to cut as much as 6" away, just enough to remove the threaded nut. Then you can connect the rocker end of the pipe to the dizzy vac unit with a suitable bit of tubing - like this: https://www.morrisminorspares.com/ignit ... pe-p831074
As Phil points out, the 'flame catcher' should be upright and in the way that he states. The pipe is normally routed round the front of the rocker cover and secured by a little bracket as described by 'olonas'.
That’s the pipe. I think the OP is looking for the flying saucer vacuum unit for the distributor.
Stephen
Ahh, my mistake, though it does illustrate the point others have made about the correct positioning of the flame suppressor.
I do wonder about the need for it. My car doesn't have one.
The classic Mini stopped fitting them around 1968..., I don't recall any of my early cars of other brands having them, Ford or Vauxhall. I wonder if they just realised they weren't worth fitting?
Vacuum advance units.....
Well, I've had a few new ones from dealers and Fleabay and the majority are cr4p , if you're used to sucking eggs it's easy, just suck on the pipe fitting and without letting go, cover the pipe opening with the end of your tongue... you'll be able to feel the vacuum holding onto your tongue.
The better the unit is the longer you feel the vacuum... you can also see the mechanism move..
Expect a 60% failue rate with new units ( cheap chinese? ).
Sleeper wrote: ↑Tue Feb 20, 2024 7:59 am
Vacuum advance units.....
Well, I've had a few new ones from dealers and Fleabay and the majority are cr4p , if you're used to sucking eggs it's easy, just suck on the pipe fitting and without letting go, cover the pipe opening with the end of your tongue... you'll be able to feel the vacuum holding onto your tongue.
The better the unit is the longer you feel the vacuum... you can also see the mechanism move..
Expect a 60% failue rate with new units ( cheap chinese? ).
John ;-)
The advance units from Distributor Doctor are very high quality UK made.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Its very important to know where we can get good parts and avoid the poor repro's. Very frustrating to fit a replacement part and find out it doesn't do the job - which could lead you to hours faffing about investigating other potential causes if you assume the replacement is good. The good Doctor is a little more expensive than some places but at least you know his spares are the business.
Thanks for your replies. For interest I've spent a few days back and forth speaking with the distributor doctor. I gave him the serial number from my dizzy. Turns out it's from an Austin A60. He said if I'd have just gone for an ebay 'Lucas' badged 25d replacement vacuum it wouldn't have been any good. He was so knowledgeable. He's supplying a reconditioned vacuum advance, new springs and a replacement cam to match the curve for a Marina engine. In line with what other replies in this thread said it is more expensive but I'd have just been wasting my money trying to swap it over with incorrect or cheaply made parts. Now all I have to do is swap them over!
Thanks.
jammmorris wrote: ↑Wed Feb 21, 2024 6:19 pm
Thanks for your replies. For interest I've spent a few days back and forth speaking with the distributor doctor. I gave him the serial number from my dizzy. Turns out it's from an Austin A60. He said if I'd have just gone for an ebay 'Lucas' badged 25d replacement vacuum it wouldn't have been any good. He was so knowledgeable. He's supplying a reconditioned vacuum advance, new springs and a replacement cam to match the curve for a Marina engine. In line with what other replies in this thread said it is more expensive but I'd have just been wasting my money trying to swap it over with incorrect or cheaply made parts. Now all I have to do is swap them over!
Thanks.
Excellent news. Martin Jay really knows his stuff. You pay for the quality of the parts and for his knowledge.
Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.
Interestingly some Marina distributers did not have a vacuum advance. It was excluded to help cure a crankshaft rumble.
Before 1974 the distributer was a Lucas 23D4 or 25D4. Post 1974 the distributer is a Lucas 43D4, Lucas 45D4.
The 1275cc H.C. timing should be set to 14 degrees B.T.D.C. stroboscopic @ 1000 rpm and 9 degrees B.F.T.D.C. static.
The centrifugal advance should be 18 - 22 @ 4000 rpm.
The serial number of the H.C. distributer is 41372 & L.C. distributer is 41234.
Any modifications carried out to the 1275cc 'A' series i.e. carb or head may invalidate the timing setting quoted above and below and taken from the Marina workshop manual AKD 7555 (sixth edition) and Ital supplement AKM4580.
The Marina/Ital 'A' plus distributer Lucas 45D4 (or Ducellier) was different in that it had a different means of fixing the distributer to the block and was serial number 41864 (Lucas) & 525294 (Ducellier).
The centrifugal advance was 24 - 28 degrees at 5200rpm.
As an aside - if you have a Marina or Ital 1275cc engine fitted it is best to have a Marina/Ital workshop manual to hand. There is far more detail as regards repairs, settings and adjustments in the Marina/Ital workshop manuals than there is in the Minor workshop manual.
Thanks Phil. Martin mentioned that the Marina didn't have a vacuum advance but he didn't know why so I'm sure he'll be interested to know. I have a Marina manual I use alongside the Minor workshop manual.
Thanks for providing the settings. Once I've swapped the parts over I'm going to pay for a professional mobile engine tuner to do a long overdue set up. Hopefully he'll get it as close as possible to how it should be.
Regards.
