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MG MGA - TDC

How can I mark Top Dead Centre accurately enough to be able to time the car? I propose to put electronic ignition in the car, but I can’t until I can guarantee that I can identify TDC. I have a mark on the pulley put nothing to mark it up to on the engine.


Garreth
Garreth

I've never tried this on an MGA, but the method is as follows. You put a special tool into the spark plug hole that is essentially just a "stop". It hits the top of the piston near TDC and keeps it from rising further. Now, by hand, turn the engine over clockwise until it hits the stop. Mark the spot. Now turn it over Counter-clockwise (or anti-clockwise, depending on whether you're British or American) until it hits the stop again. Mark the spot. TDC is exactly half way between the two marks.
Steve Trovato

Garreth,
I have the luminition electronic ignition on two MGA's, but they don't care where TDC is.

So I'm guessing your going for Full distributor less ignition, with optical crank pickup. This kind of thing right?

http://picasso.org/mjlj/?q=node/2

The above method works well, only on No 1 or No 4 cylinders though. I break an old spark plug and remove the inners then screw that into No 1 and insert a fine poker.
As described Steve, rock the engine back and forwards, you'll get there.
Take some pic's and post them when you get your kit fitted.
Good luck
Cheers <MARK>
Mark Hester

Take a look at the Supercharger BBS (click subjects on the headers of this page) and look at the EDIS thread - lots of stuff on tooth wheels and sensor mounting (it's where all the performance nuts hang out!)
dominic clancy

Dominic,

If you find yourself in Geneva with you supercharged A, give me a ring.

Cheers <MARK>
Mark Hester

Garreth,
Take number one spark plug out and wad up a piece of paper towel. Push it tightly into the spark plug hole. turn over the engine by hand and it will pop out the paper when you reach nearly TDC. Then using a long wire, place it into the spark plug hole as Mark describes. When the wire ceases to rise and starts to fall, you are there.
mike parker

Remove the valve cover and rotate the engine by hand. Watch #4 cylinder valves. When the valves are rocking,(exhaust just closing and intake just opening)
Now turn the engine until the long pointer is in line with the dimple on the crankshaft. Now #1 is at T.D.C.
Jim.
Jim Jensen

This thread was discussed on 24/05/2006

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