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MG MG Y Type - Timing chain

Hi all

We had a weekend away in the Y, along with 7 other club members. [The whole idea of the event was to use your [older] club cars - apart from ourselves in the Y and the event organiser in his similar aged Holden, the rest were all in what I call modern, the youngest early '70s.]

Getting to the point, the car played up, and I'm wondering if the timing chain has jumped a tooth. No amount of adjusting the carby achieved anything. It popped and back fired, lack of power etc. Started on the way out when we still had about 50 miles to go, and all the way home for another 120. Did I mention we were travelling across the central highlands of Tasmania to boot? Could also be points, plugs, fuel supply (don't think it is that].

I have yet to get out and check things out; last night I was too tired to bother, and tonight I have to head out again.

Any clues on how easy/hard it is to replace or reset a timing chain in situ if that is the problem?

John Turner
Tasmasnia
J B Turner

Hi John,
Start with the plugs, one or more are probably black, fouled up and not working. Don't replace with the standard plug - go one hotter in the heat range.

If it's not plugs, check the plug leads, then the cap, and so on, working your way back to the coil & points.

Once you have found the ignition problem, go back a setup your carby from scratch again, this time fitting lean needles and the float level 5mm below the bridge. You can also check your needle valve is not leaking at the same time - which can cause rich running & fouling of plugs !.

Enjoy the experience.

Tony
A L SLATTERY

I agree with Tony, John. Do all the simple stuff first.

I would even go one stage before Tony and swap out the distributor rotor arm for a new one. If yours is begining to fail you may be getting a degraded spark. If that isnt the cause then you know you will have a spare in the glove box.

You really dont want to start worrying about the timing chain. If it had been that then you would probably have slipped another tooth on the 120 mile trip home.

Paul
Paul Barrow

Just remember that 90% of carburettor problems are INGITION. I have never seen a timing chain jump timing on an XPAG type engine. I would suspect the condensor long before anything else.Also check the upper bushing in the distributor body as if it is badly worn you have all sorts of intermitent problems.My tf would not idle on #4 cylinder at all yet run fairly decent at speed. It was play in the bushing that allowed the point cam to wobble.
darnoc31

Thanks for your advice, it's much appreciated. I pulled a plug when I got home, but forgot to take it to work today as getting a hotter plug was one of the things I had in the back of my mind. Did that on my '25 Willys Knight a couple of years back when nothing else seemed to work - not only fixed a rough engine but gave me more power up the hills - needed it as the engine is still original as is the rest of the car.
Will let you know what I find when I get to it. Thanks again.

John
J B Turner

Got some new plugs today to replace the ones in the car. Was curious to know what everybody else uses around the world, and if any particular plug has proven to be better than any other (if at all).

For the record, the car had NGK type B6S fitted, and I have now got a set of NGK BP5S. The lower the number, the hotter the plug.

Out to the cold shortly to fit same and start checking a few things.

By the way, has anybody got a spanner like the picture below? A mate needed one for his SU to adjust the adjusting nut without having to undo things, so he made two while he was at it.

John

J B Turner

Hi John

Moss and many other outlets sell them as SU Carburettor spanner/wrenches either on their own or as part of a larger carburettor servcing kit with other stuff. That is where I got mine a couple of years ago.

Paul
Paul Barrow

Hi John, I'm with Darnoc on this one. I would suspect that with the sudden onset of problems that the condensor would be the first item on my check list.
Terry Y2866
T J Ciantar

The NGK equivalent to the standard Champion L.10.S (or L.82.C) is B6HS. Fouling of “Standard Heat Range Plugs” is a common problem with unleaded fuels – especially driving “around town” & cold starts.

I adjusted the float correctly and changed the needle for a leaner type. Even then, the mixture was too rich, even with jet all the way to the top. After a few hundred miles, the plugs were fouled at the gap with much black carbon deposits. The engine started hesitating.

In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber. For NGK, the lower the number, the hotter the plug.

So I swapped my B6HS for B5HS and the problem is clearly much more under control. The tip is now much cleaner and brownish, as it should be. Engine temperature (which was unusually cool) is more normal and performance is a bit snappier too.
Gilles Bachand

I had a series of problems with various rotor arms braking down, after now changed to the red rotor arm as advertised in SF, there has been no more spitting and mis-firing. Bryan
B Mellem

This thread was discussed between 12/06/2012 and 14/06/2012

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