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MG MGA - distributer position

Looking through the archives recently my eye caught on a thread regarding the position of the distributer that was said to be with the axis of the vacuum unit near vertical or even at the 11 o clock postion. I've always had mine at nearer the 2 o clock position. Checking with Clausager the photographs are not clear but they do suggest that the vacuum units are indeed near the vertical. Is there a generally accepted correct position for the distributer and does this give advantages over other positions?
J H Cole

Picture may help


J H Cole

When the distributor drive gear was installed it was inserted 1 tooth off. You have turned the distributor around to the right to compensate. There is no real need to change the installation except to make it "right". If you do change it you will have to re bend the vacuum advance tube and it may break if you are not carefull. To reset the dist drive gear you bring the engine to TDC on # 1 and remove the distributor. Underneath the distributor, held on by 2 flat head machine screws, is the piece that retains the drive gear. Take a 5/16 fine tread bolt about 4 inches long and screw it into the center of the drive gear. Using the bolt as a tool pull the gear just far enough to turn it so the slot points to the 11 o'clock position when reinserted, probably one tooth to the right of where you are. Then reassemble and set timming.
The picture shows the drive gear in position and the retaining piece and the screw that holds it in.


R J Brown

The retaining piece is held on by one flat head screw as pictured not 2 as I stated.
Oops can't edit after you hit Submit.
R J Brown

Thanks RJ but why can't I just rotate the distributer 45 degrees anti clockwise to the next spark position and then swop the leads around to conform to the new sparking sequence: ie ensuring there is a spark going to No 1 at tdc or have I by then lost the 1:3:4:2 sequence.
J H Cole

The shop manual provides slightly different instructions for refitting the drive gear. #1 on TDC on compression stroke with pully notch lined up on the long timing pointer. Turn the engine back to 7 degrees (between the two short pointers). Enter the drive gear with the offset slot below horizontal with the large offset uppermost. As the gear engages, it will turn counter clockwise. When fully engaged, the slot should be pointing approximately at 1:00.

Since you will be unable to see the final result (assuming the engine is still in the car), I would put a mark on the bolt used to hold the gear that matches the slot and use that mark as your 1:00 reference.

Reinstall your distributor and retime the engine.

Barney's site has a really good description of the process. See:

http://mgaguru.com/mgtech/ignition/ig103.htm

Good luck and don't drop the gear into the sump (that happened to a "friend of mine.")

Don Carlberg
Don Carlberg

It would be 90 deg to the next lobe (would it not?)and that would be too far. It should be pretty easy to do as RJ says. Either way you would still need to reset the timing.

If it's running well, I would be tempted to leave as is, at least until the next points change.

Neil
Neil McGurk

Neil, yes of course its 90 degrees not 45 and as you rightly say this would be too much of a rotation. I will have to go back and reset the drivegear as described above.
J H Cole

Don's warning is very valid. Last year I tried the process with the drive gear on my spare engine before doing it on my installed engine. It is still in the bottom of the sump! At least it won't rust there.

Steve
Steve Gyles

Engines are stupid they don't care where the gear or cap or wires are as long as the spark is at the right time.There are many ways to put it together and still run. Your situation shows this. The only reason for change is to do it right. A non standard installation would work. It really is a simple procedure to correct the situation properly. Changing the position of the wires would also work.
R J Brown

Don is correct the slot is at 1:00 postion. To avoid dropping the gear use as long a bolt as possible for the tool. The pictue I posted is of a block without the crank and is wrong. See Don's note above. That is what I get for using just my memory and not reading the book.
This book is for both A and B the installed picture in bottom right is from a B and is at 2 o clock.


R J Brown

This thread was discussed between 17/01/2008 and 18/01/2008

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This thread is from the archive. The Live MG MGA BBS is active now.