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MG Midget and Sprite Technical - 1500, any ideas ?

I've had my 1500 since last August and done about 1200 miles in it, its only covered 1500 miles in the last 12 years so no use at all.
Last September it started to run on 3,once I'd switched it off for 5 minutes it ran fine, I checked the valve clearances and one was non existent after that it ran fine, fast forward to last Friday the same happened except 4 out of 8 clearances were tight.
Looking at its history do you guys think that because it had its head re faced, seats cut , valves etc in 2008 but its only done 1500 tops its settling down ?
Scott Coe

If it has had the seats recut then it may be suffering seat recession - were unleaded exhaust seats fitted?
Chris at Octarine Services

All the bill says Chris is
Cut seats
Face valves
Face head
Cam followers
Scott Coe

Do you remember or did you notice which four were tight? If it was all the exhaust valves, that would be a strong indicator to it being VCR.

Wang loads of additive through it and hope that it fixes itself whilst continuing to reset the clearances.
Malcolm Le Chevalier

If you are really skilled you can match your cam wear with the speed of VCR so that your valve clearances always remain in spec ;-)


Malc.
Malcolm Le Chevalier

I'm no expert but it surprises me that valve recession could be as quick as that if Scott has only done 1200 road ( Not track) miles in it.

What about cam lobe wear or even has it been assembled with wrong lock nuts in the rockers and they are working loose?
GuyW

Malcolm I don't remember which ones, what's VCR mean and what additive ?
Scott Coe

Duh!

Valve Ceat Recession of course! ha ha.

Once would have been a mistake, but twice shows I am just a bit thick!

A lead replacement addative.
Malcolm Le Chevalier

Malcolm, blame predictive text. I always do!
GuyW

Makes sense now Malcolm , I use a lead additive, castrol master and 99 octane
Scott Coe

The quality of aftermarket components varies such a lot these days. A set of cam followers from a very well known supplier lasted barely 5000 miles. They were incorrectly ground which meant they did not rotate. Swiftune supplied a new set and explained that they went through a careful quality check to ensure accuracy of grind and hardness. Time will tell! None of these components are manufactured in the UK any more.For example billet cams used by Kent Cams,Piper and the like are all produced in Turkey.
Bob Beaumont

About 10(?) years ago I got a water pump and was considering getting the Mini competition(?) one but I was told the standard Spridget one the supplier had was made in Turkey and despite it's price being the same as previous ones the Turkey pump was well made. Apparently (at the time) the Turkey company for reasons I forget were no longer able to make parts for big boats (ships?) and needed work and they were used to working to high standards.

IIRC one from Turkey was £13, Mini special £20, Turkey pump still going strong (that's blown it!).

Let's hope things haven't changed that much.

China used to make things to high standard but then things changed (they learnt western ways of business?).
Nigel Atkins

At the risk of looking an idiot again - I've always thought (remembered?) the Upper Cylinder Lubrication mentioned in the lubrication chart in the good book was referring to an additive to the engine oil - am I wrong?

I know you can get petrol additives and engine oils are a lot different and better today than they were back then, even the ones with the same name like Castrol XL, Duckham Q and all the others.
Nigel Atkins

Upper cylinder lube usually either goes in the fuel or gets metered into the inlet manifold or carb.

If Scott's been using Castrol valve master-lead and it's low mileage there 'shouldn't be valve recession,-- but it sounds like it has

The only reason I can think of is that, it's common practice in some machine shops to cut the valves at a slight(1 deg.) different angle when synchro seating to promote good sealing without having to bother lapping the valves in---44 deg seat-45 deg valve, SO , maybe, just maybe whoever did the job might have got a bit excited and overdid the angle job with too much difference in the angles and the valves are gradually moving into the seats---If this is the cause, it'll settle

I'd run it as Malcolm suggests , just adjust it up every now and then and it 'should' settle down after a few times

willy
William Revit

Cam lobe or follower wear will INCREASE the valve clearance as will a loose rocker shaft.

Has to be valve recession if the gaps are closing.

Don't leave it - too much recession and the head is scrap. You need to take the head off and examine the seats and have hardened seats fitted if necessary.
Chris at Octarine Services

Thanks Willy, I suppose there was a clue in the name but the wrong idea stuck in my mind.

Now at the risk again - do I take it this is where the old Red-X came in?

I think of it as a cleaner because as a kid you'd use it as such or to see how much black smoke you could get out of the exhaust of the old banger you or your mate had just bought.
Nigel Atkins

If the clearances are tightening up it is either:

Valve seat recession,
or
stretched valves,
or
Adjuster nuts winding themselves loose,
or
Valves settling down in their seats.

Now, after 1500 miles it is highly unlikely that you have recession.
Its also highly unlikely that your valves are stretching (unless they are of abysmal quality)
Its also next to impossible for the adjuster nuts to come loose and then have the adjusters wind themselves tight.

In my opinion, you may well have a situation where the seats and valves are settling in to each other.

Its worth noting that if you have retorqued the head it may change the clearances by a very small amount too but no way enough to close up the clearances.

I would make a note of which ones were tight, readjust and drive it some more, check again in 500 miles.

You should find that it all settles down after a few more miles.

Just my twopenneth worth.

Skelly.


Jon Skelly

I suggest checking the head torque and then adjusting the valves. Then drive the car regularly until everything beds in. The cars are very reliable if driven daily or at least frequently.
Glenn Mallory

This thread was discussed between 22/05/2020 and 06/06/2020

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