Distributor Vacuum Unit

[geoberni]

So call me a bit fussy, but while doing some Timing work on the engine (found all the tappets set to about 6-8 thou which could explain a lot of things....), I was wrapping up and just thought I take a quick look at the Distributor...

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I'm pretty sure it shouldn't do that

Anyone changed a vacuum unit recently...?

It is possible the adjusting screw has just become detached, or is it likely busted?

[philthehill]

You should not be able to pull the vacuum advance unit as you have.
I would fully remove the vacuum advance unit from the distributer making sure that nothing falls down into the distributer works and examine for damage/faults.
I suspect that the adjustment rod has parted from the vacuum advance diaphragm body which is not unknown
.
Below is how it should be.

http://www.morrisminorspares.com/igniti ... pe-p831047

As it is currently your ignition timing will be all over the place.

As regards the valve clearances - the 'A' Series runs better with 0.015" clearances.
Do you have a unleaded head? If not the valves may be working their way into the head so closing up the valve clearances.

[geoberni]

Hi Phil
Thanks for your quick response.
Well I got the busted vacuum unit out (the circlip on the end of the adjusting screw was a little beggar) and I've given a suck on the bellows and it leaks like a sieve, so no point in trying to reattach the adjuster!

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Powerspark and Accuspark replacements are around £16.45 on ebay, so I guess that's the place to go, especially as the Powerspark one comes with a 2 yr warranty.

Oh, and to add...
I'd not checked Basil's Tappets and was very surprised to find them so tight. I was expecting them to be somewhere near the book settings, although I was intending to see them at 15 thou because I'd read up on here about setting them.
Basil was changed to a 948 Mini engine in around 2010 as far as I can tell, as in the limited history I have, there's an inspection letter from a garage to support a change of engine with the DVLA. On that basis, the assumption is that it's a Lead-free head.

[Declan_Burns]

Geoberni,
I have my serious doubts that you have a 948cc mini engine in there. I would also doubt that it has an unleaded head.
I would also just replace the vacuum unit and keep the original 25D. The distributor caps on those cheapy distributors are rubbish. I had two failures within a year on those caps.
Regards
Declan

[philthehill]

Whilst you can convert and fit a Mini engine to suit a Minor it would not be cost effective to do so.
The Mini engine was not factory supplied as a 948cc unit.
If you have a 948cc engine fitted I suspect that it is a Morris 1000 948cc engine.
The only way to determine what engine block you have fitted is to quote the block casting number which can be found at the N/S/R of the block.
Again the only way to determine if the cylinder head has been adapted to use unleaded fuel is to remove the head and examine the valve seats.

[ManyMinors]

There is, in any case, no such thing as a 948cc Mini engine..... I expect it is simply a Minor 1000 engine.
I wouldn't worry about an "unleaded head" My Minor doesn't have one and is used almost everyday, running happily on unleaded fuel. It has done for years. I don't use any additives.

[philthehill]

Whilst a Minor 1000 engine will run happily on unleaded fuel and leaded seats it is prudent to open the valve gaps to 0.015" (especially the exhaust valves) and check the valve gaps on a regular basis so as to counteract any valve regression into the head.

[geoberni]

Thanks for the additional replies.
To provide some answers:

I may be wrong about the 'Mini' bit as that was word of mouth from the guy I brought the car from, and as I've mentioned before, he was a self confessed Automotive Luddite who really knew naff all about the engineering of the car, he just drove it; however in the paperwork I have a garage inspection letter saying it's a 948cc Goldseal replacement engine number 8G162 ER56559

I know the 8G designates it as an Gold seal, if anyone can decipher the 162 part, please do.

The car was restored/overhauled whilst with it's 2000-2010 Owner and the engine change documented in 2010.

Sorry if I confused anyone about replacing the distributor, I was just referring to replacement vacuum units on ebay :

https://www.ebay.co.uk/itm/25D-distribu ... SwPCVYBkR8


I can't imagine why the gaps were so small, and consistently so too. I did a Compression test last night (before I found the loose vacuum unit) and all cylinders were around 125/130 psi.

[geoberni]

So replacement vacuum unit arrived; works fine, although good job I didn't need to use the nut that came with it. Might've had a problem getting it to rotate in the slot, seeing as it is a bit off true....

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