Vacuum Advance.

[Guildbass]

Well, during the course of fiddling, an d checking timing (horribly retarded), I noticed removing the vacuum advance pipe made no difference to engine running so I popped the distributor cap off and gave the pipe a suck... Yep, just draws air and the dizzy back plate doesn't move.

Ordered a new one from ESM which duly arrived.

I needed to set the points gap and fit this new part to the distributor so it made sense to me to get the distributor out.

First thing I did was get the engine crank handle, go under the front until I could see the timing marks and rotate the engine to the top dead centre mark (the taller 'spike' on my '68.

Then with the cap off, took a reference picture showing where the advance/retard vacuum nozzle was pointing and where the rotor arm was set.
Unplugged the wire going to the points

Removed the dipstick so I could get a 7/16th socket in there, slackened it off, and the distributor came straight out...Excellent.

The vacuum advance on the type 25 includes the vernier wheel adjustment and is actually held in place by that rotating wheel.
On the original there is a tiny circlip type piece on the end of the threads to stop the wheel coming all the way off, so that needs to be prised off and then the wheel can be turned until it leaves its threads and the whole assembly then just pops out.
The new one goes in and the spring goes on the adjusting wheel side to pre-load the wheel.
You HAVE to use the adjuster wheel that comes with the new unit as the threads are different. Also, there's no retaining circlip
What I FORGOT to do was wind the adjuster in half way to give me adjustable advance and retardation... Damn!.

Adjusted the points to 15 thou, offered it back up with the angles about right (from my photo), wiggled the rotor arm and in it went.
Now, back under the car, rotated the engine until the crank pulley mark was at the 8 degree before top dead centre mark ( between 2nd and 3rd 'spike'). Then after reconnecting the points wire, ignition on and rotate the distributor until the points opened with an audible electrical 'crack'. as soon as I heard the 'crack' rotated it back a smidge, (about enough so the snout on the end of the vacuum rotated back about half an inch. Nipped up the clamp, put the cap and vacuum pipe back on, started it, and checked with the gun...Absolutely spot on!

Put it all together and went for a run. Adjusted mixture to err very slightly lean and went into Tisbury for sweets and petrol. They have 100 octane ethanol free there....
Never noticed before but these engines have a definite sense of 'coming on the cam' at about 60 (?) in top.
Still trying to get all the sounds organised too. ... Induction noise.... or main bearings....No one knows...
Tomorrow, its brakes...Again...

[svenedin]

Good job. I would have purchased the vacuum advance from Distributor Doctor as these are absolutely the same as the original.

Stephen

[Sleeper]

" just draws air and the dizzy back plate doesn't move.

Ordered a new one from ESM which duly arrived. "

Did you " suck test" the new one , I've seen faulty new ones...

John ;-)

[Guildbass]

Good job. I would have purchased the vacuum advance from Distributor Doctor as these are absolutely the same as the original.

Stephen

Ah well, ... To be honest, the less I have to do with ignition timing the better so it's getting some kind of electronic 'fit and forget' soon. I like originally but some things ARE better than they were!

[Guildbass]

" just draws air and the dizzy back plate doesn't move.

Ordered a new one from ESM which duly arrived. "

Did you " suck test" the new one , I've seen faulty new ones...

John ;-)

I did indeed, and even checked the old one again once off. The new one maintained a 'vacuum' so it stuck to my tongue, but moved the plate in a very satisfying way!

I still can't get over how incredibly flexible and torquey the engine was when the timing was 10 degrees AFTER TDC though, as it was when I got the car. It went so well
... It was only the engine noise above about 60 mph that gave me pause. There's more top end now, and a willingness to rev, but I miss it pulling from 10 mph in top...You never needed to change down

[myoldjalopy]

How long are these things meant to last anyway? I have never had to replace one but maybe modern replicas are liable to failure? I guess anything from the Dizzy Doc would be good quality though........

[svenedin]

How long are these things meant to last anyway? I have never had to replace one but maybe modern replicas are liable to failure? I guess anything from the Dizzy Doc would be good quality though........

There’s a rubber diaphragm inside that eventually either goes hard and won’t move or perishes. The last decades I think.

Stehen

[Guildbass]

How long are these things meant to last anyway? I have never had to replace one but maybe modern replicas are liable to failure? I guess anything from the Dizzy Doc would be good quality though........

I never thought they.d be a thing that fails but at the end of the day, it's got a flexible diaphragm in it exposed to the atmosphere. ... Not something I've ever checked other than to see one move the points platform.
However, if it was thst uncommon no one would be making a new replacement part, so.....

[Sleeper]

I've found a 50% failure rate on the cheap chinese items....

https://www.ebay.co.uk/sch/i.html?_from ... =0&_sop=15


Buy cheap buy twice?

John ;-)

[geoberni]

Back in 2018 when I was having 'dead ignition' issues, although that was eventually traced to an intermittent Coil, I found that the Diaphragm on the Dissy was leaking.
I ordered one from the ebay account of a reputable Ign parts supplier.
The hole/thread in the Adjuster was crooked; I had to swap the nut over from the old one
Luckily, it was the same thread and not a mismatch. Photo I took at the time.

20180915_111804.jpg (989.56 KiB) Viewed 461 times

[svenedin]

We know that Far East Lucas copy distributors are being made and sold by the likes of Powerspark, Accuspark and others either with electronic ignition or points already fitted. I examined one of these units and I thought it was dreadful quality. I suspect the replacement advance units are of the same cheap shoddy quality. The only decent parts for Lucas distributors I am aware of are either new old stock or made by Distributor Doctor. In the case of the advance unit there is no point buying new old stock as the rubber diaphragm perishes over time whether in use or not. Distributor Doctor will also rebuild a customer's own advance unit so don't throw them away. Remember the advance unit is meant to be calibrated to operate a certain degree of advance at a certain pressure. You get what you pay for. The Morris Minor is deceptively simple. Little things like this are actually precision parts that must work to specification.

Stephen

[Guildbass]

[. Remember the advance unit is meant to be calibrated to operate a certain degree of advance at a certain pressure.

Stephen
[/quote]
Do these units have different diaphragm stiffness according to the curve required then?... And if so are they marked in some form to distinguish one from another?

[svenedin]

[. Remember the advance unit is meant to be calibrated to operate a certain degree of advance at a certain pressure.

Stephen

Do these units have different diaphragm stiffness according to the curve required then?... And if so are they marked in some form to distinguish one from another?
[/quote]

To be honest I don't really know. What I do know is that there is supposed to be a certain degree of advance at so many mmHg of vacuum. Where I found the figures is anybody's guess. There are books of figures for distributors and so many variations that it is mind boggling. That is why I leave it to the expertise of Distributor Doctor. He asks for the distributor number before he will sell parts so that there is no mismatch. For example, the distributor in my car is a Lucas 25D4 41269 and various different variations of this distributor with different codes but the same basic model were used in the Morris Minor 1098cc.

Stephen

[Guildbass]

Well, after getting the timing sorted I thought I'd give it its first proper run as my errant offspring were meeting up near Cadnam, some 30 miles away and requested my attendance.

So, 7 miles of fast 'B' road, through busy busy Wilton/Salisbury, down the A36 and off into the bushes,

My dad always used to potter along at about 50 mph, declaring 'it would shake itself to bits' at any higher speed.

My 1098 romped up to 60 with barely a brush of the throttle and up to 65 where a front wheel balance issue reared its shaky head, then on past 70 to an indicated 80, or 72 mph according to the GPS which confirmed like many other cars and with those radial 145/80's on the rear, the speedometer is 10% optimistic. Still, not bad and it felt perfectly sustainable.
I did notice a growly front wheel bearing when taking right turns so that needs a deft adjusting up.
Didn't use a spec of oil or water although I did give the mixture a couple of tweaks, no more than half a flat, to keep it clean once properly hot.
they're great little engines, I just wish mine didn't have what I think is a chattering tappet...Which probably means a scored lobe.
it's had 65,000 miles of short journeys with 20W-50 in so heavens knows what the shells look like! oil pressure is still 'lights out' at a very ,ow idle once fully hot...
Oh, those electric oil pressure gauges they have on Amazon and the like, how universal is the A series's oil pressure switch threads, or do i need a special one?

[Bill_qaz]

If you use the search, lots of posts about fitting oil pressure gauge, either T at oil pressure switch or remote mount T piece.

[philthehill]

I would recommend using one of the modified unions pictured below. It fits into the pipe from the block to the oil filter. Fitting and accessing the oil switch is easy.
https://www.ebay.co.uk/itm/166642222294 ... R8Te19_gYw
I have purchased two from the above 'e' bay seller and it is much easier to fit a oil pressure gauge using one of these adapters.
You can drill and tap (1/8 National Pipe Thread NPT) the original union to achieve the same end but for £8 it is not worth the effort.

modified oil union.jpg (125.52 KiB) Viewed 185 times

[panky]

Ditto. Here's one in the process of connecting a pressure gauge on my engine

[Bill_qaz]

Or here is the T into original switch position, not as accessible maybe, although my vacuum advance position doesn't help but it could be repositioned.

20240323_125911.jpg (117.23 KiB) Viewed 145 times