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MG Midget and Sprite Technical - timing chain change

While i have the engine out i went to change a noisy timing chain it was a one piece so had to remove cam gear when i went to refit new chain i discovered that there were no timing marks on crank drive cog. Manual not much use so can you refit cover and pulley and line up to TDC then on the front plate there is a punch mark which i have lined up with the cam pulley mark.see pics


mark 1500 on the road Preston Lancs

cam marks


mark 1500 on the road Preston Lancs

tdc i assume these are correct and is there anything else i should check.


mark 1500 on the road Preston Lancs

just checked and with all the marks as above dizzy just past no4 and valves 1 & 2 are rocking on open and closed and valves 7 & 8 fully closed, with my limited knowledge this seems correct?
mark 1500 on the road Preston Lancs

Erm... sounds OK I think Mark. Not sure if understood your OP correctly though.

If you didn't remove the cam or disturb the dizzy, if you check your timing (using a timing light) and it still hits 10 deg BTDC (assuming it was set up to factory spec originally) then you are good. i.e. you have three things linked together wrt timing. crank-cam-dizzy. If the cam-dizzy relationship has not been disturbed you can use it to check the crank-cam relationship by virtue of the ignition timing.

Does that makes sense to anyone else other than me?! :-D

Malcolm
M Le Chevalier

been checking archives and found this

Set valve clearances at 0.050", (1.27mm) on valves 7 and 8.

Turn engine untill both rockers are depressed and are just touching the ends of the valves. At this point the camshaft is at the correct rotation for top dead centre for no 1 cylinder at the beginning of the firing stroke.

Check timing marks.

If timing mark is at 0 deg, then all is well. This is because standard timing on a midget 1500 is inlet opens the same angle ( 18deg) before top dead centre as the exhaust closes after top dead centre.(again 18deg)

so i set cam to this and put crank to zero and fit chain i am assuming that this is correct
mark 1500 on the road Preston Lancs

According to a well known book there are timing marks on the sprockets.

I must admit that I did not relish this part when I replaced my tensioner so was relieved when the chain checked out OK and left it alone.

Hope the pic helps.

Cheers, Dave


Dave Squire

thats ok if everything is original no marks on my crank just on cam gear wheel.
mark 1500 on the road Preston Lancs

I don't suppose the crank sprocket is on reversed is it? Can it be fitted reversed, with the mark then hidden from view?

As they're all the same, maybe someone with a 1500 could inspect a (spare) sprocket for you, and give you the exact position of the timing dot?
Lawrence Slater

Looking at moss site it looks like it will only go on one way, it dose say in the haynes manual that some do not have any marks.found this in the good book set it to tdc and lined up pulley mark to zero and fit chain.had to turn cam gear wheel to line up exactly apparently acording to spitfire site it can be fit in 4 positions to give slight 1/4 cog adjustment.



mark 1500 on the road Preston Lancs

Hi Mark,


I had this dilemma when I rebuilt my lump after 4 years. In the end I think I worked it out from the marks on the rear of the cam wheel.


I think there was a slot in the cam that lined up with the old oil mark on the wheel?


Seems to go ok, so it must be correct!


Regards Steve
SR Smith 1

Is the illustration 5 posts back correct for a 1500? I would set it up just like that; it's clear where the dogs are in relation to each other, the centre line and their sprocket teeth.

Turn the engine very carefully, though. I don't know anything about 1500s, but on a 1275 the big-end bolts can hit the cam lobes if it isn't correct.

Nick and Cherry Scoop

no thats for a dfferent engine this is 1500 with timing marks


mark 1500 on the road Preston Lancs

no thats for a dfferent engine


mark 1500 on the road Preston Lancs

If desperate have you tried phoning Triumph people, such as Jigsaw Racing for advice? (Or Canley Classics?)

Cheers
Mike
M Wood

I'd strongly recommend that anyone keeps well away from Jigsaw Racing - the guy used to be a meat butcher and has transferred to being a car butcher
Nigel Atkins

to be more positive -

the guy I'd ring about Triumph stuff is John Yarnell of JY Classics - http://www.jyclassics.co.uk/
Nigel Atkins

This thread was discussed between 27/10/2014 and 13/11/2014

MG Midget and Sprite Technical index

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