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MG MGB Technical - Can't loosen ditributor nut

Silly question but I have a 79 B with 45DE4 distributor and I can't get a wrench on the nut of the locking clamp that must be loosened to rotate the distributor. Any advice would be appreciated. Seems to be a 7/16" nut.
Tom Gillett

If its seized and you cannot remove it , why don't you undo the nut holding the distributor fixing plate to the block and pull the lot out and then free it out of the car?
Both of these nuts/bolts can seize if there is a water weep from the heater valve situated above the distributor - I know cause it happened to me!
AdrianS

If you mean you can't get a spanner on the nut (or rather the head of the bolt, isn't the nut square and captive?), rather than you can but it won't move, it does need a slim ring-spanner, I use a ground-down one for these, and the clamp plate bolts as well as the heater tap bolts. It's very easy to overtighten the clamp bolt, and distort the shoulder on the alloy body of the distributor, then it starts jumping out. You also need to make sure that after having twisted the distributor in the clamp plate - or having removed and refitted it - the the distributor body is fully seated in the clamp plate. With the clamp plate bolted down to the block this ensures the distributor drive dog is correctly seated in the drive gear. If it isn't then tightening the clamp plate bolts will push the distributor out of the clamp plate, but maybe not all the way so you don't realise it until you crank the engine and it jumps out altogether.

If making small adjustments to timing then it's better to slacken the two block bolts and twist the distributor plus mounting plate using the scope offered by the slotted holes in the plate. You may need to slacken one of the clamp plate bolts in any case in order to allow the clamp to open up.

The vernier adjustment on the 25D4 distributors makes even significant changes in timing so easy.
Paul Hunt

Yes. it should be 7/16" AF.

You *should* be able to get a combination spanner on it.

What is preventing you getting a spanner on it? Is there something in the way?
Dave O'Neill 2

Sorry, I wasn't very clear. My problem is that I can't get a wrench on the nut and, if I do, it looks like I will not hae room to turn it now that the oil filter is in place. I can plainly see the nut but no wrench I have let's me get a grip on it. I'll try grinding one down.
Tom Gillett

In the past I've only had to remove the dip-stick to wield the spanner on the clamp bolt, as it sticks mostly upwards and is only angled a little towards the front of the engine.
Paul Hunt

The trick on the heater valve bolts is to use a C shaped obstruction spanner, makes the job really really easy!

dominic clancy

you learn something every day. never heard of or seen an obstruction spanner before.

but for my birthday got some of these...just arrived this morning.

http://chicagobrand.co.uk/product/3-piece-imperial-set/

can't wait to try them out. saved quite a bit importing them from USA. $27 price tag and they charge £50 in UK, not even £ for $, criminal! Graham

Graham Moore

Everyone needs a distributor spanner in their tool box (see photo)! These make undoing/tightning the distributor set screws a dream and are dirt cheap to make. Buy an el cheapo 7/16" spanner from your local car parts store ~$1 , cut in half, bend and weld to an old screw driver. To make even easier fit grind a bit of metal off the cheeks of the spanner. If your screws have been over tightened you can clamp a set of vice grip pliers to the handle to give you extra leverage.
Mike

Mike Ellsmore

Graham-Those Chicago brand spanners are neat;which US distributor did you use? Michael
Michael Beswick

Sorry don't know what the fuss is about! Awkward yes but not difficult. decent, slim spanners as opposed to the cheapo things with too much metal to compensate for their poor quality, are all that is needed.
Allan Reeling

This is what obstruction spinners look like



dominic clancy

"Sorry don't know what the fuss is about!"

Ditto.
Paul Hunt

Fuss is about making life easy - MGAs are a little more cramped than Bs to work on.
Mike Ellsmore

Getting at the lower nut on a heater valve is a PITA whether on an A, B or any other B series application. Unless you use an obstruction spanner, then it is a piece of cake, no need to disconnect anything else at all.
dominic clancy

"Unless you use an obstruction spanner"

A slim standard works for me. However the first time I replaced the heater tap I found the recesses for the bolt heads were shallower on the new one than the old, so I had to grind a bit off the end of the ring.
Paul Hunt

If you're looking for a miserable bolt to get to, try to get to the fuel injection pump bolts on a MB 300D. Next to impossible! RAY
rjm RAY

"Don't know what all the fuss is about."

I'll go with that, likewise heater valve.

I've just changed the direct tandem servo on my lhd B. My wife thought I'd left her.
John Bilham

This thread was discussed between 13/07/2014 and 18/07/2014

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