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MG MGA - Timing Marks in different place?

I looked underneath and there are no timing marks on the timing chain cover below the main belt wheel.

However when I was poking around from the top I found a line of five pointers painted yellow close to the top of the main belt wheel. I'm assuming these are a different type of timing mark. I'm posting some photo links. Can anybody tell me which is TDC or what the increments are?

Thanks.

http://i53.photobucket.com/albums/g64/tbm66/IMG_0372.jpg

http://i53.photobucket.com/albums/g64/tbm66/IMG_0376.jpg
Tysen

Tysen-
It's a late MGB cover; the topmost pointer is TDC, and they are 5deg BTDC increments. However, either you must have the corresponding pulley, or there must be a non-stock mark on the original pulley in the correct location for this cover. Check carefully that whatever mark is present is really at TDC, or you will be chasing your tail forever!
FRM
FR Millmore


Tysen,

TDC isn't always indicated by the external marks lining up. The mechanical arrangement inside the engine may be slightly different then when it left the factory.

If you put the #1 clyinder at it's top dead center (exactly !!) and it's on the firing stroke (distributor rotor about the 2 0clock position)the engine is then at TDC. You can then re-mark that on the external bits. (You may notice it's not exactly lined up with the timing indicator.)

Your new marks will be the basis for your timing from then on.

You can set your initial static timing using the distance on the timing marks teeth as a guide. I believe they are 5 degrees each but not sure exactly.

From there you can use a dial back timing light to set it as you like.(Using your new and guaranteed accurate mark as the TDC (0) point.)

I believe most people go for around max 30-32 degrees of advance (vacuum line off and plugged) at 3000 rpm.

Hope this helps,

Tom
Tom M

This thread was discussed on 01/07/2006

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