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MG MGA - Vacuum advance in dizzy

I just noticed that the vacuum advance spring has come disconnected from the sliding plate in the dizzy of my '59 1500. I can't seem to find any picture of what is used to keep the spring on the peg. The spring has a loop that slides over the peg but there is nothing to keep it from riding up and off the peg. I assume there should be some sort of horseshoe clip or ???

Thanks,
Dave
David Ahrendt

No clip, just the stiffness of the spring. If this has happened it could be that the spring has gone week or out of shape as they can with age, or the advance plate (that the points mount on) is not moving freely causing the spring to pucker up when trying to return the plate to the non advance position. Denis
Denis4

Pictures of early and late advance mechanisms are here:

http://home.comcast.net/~eastmanb1/MG/MGA_distributor_work1/Dizzytest_simple1.htm

Bill
Bill Eastman

Oops, just notice you asked about the vacuum advance. Not sure why I'm having trouble reading the posts lately.
Bill
Bill Eastman

Come on Bill, you just wanted to show off your project! Superb stuff it is too!
Neil McGurk


Thanks for the info Denis.

Does anyone know who sells internal parts for the DM2 distributor? The usual suspects seem to only carry points sets, caps, rotors, just the tune-up stuff. Anyone selling the sliding plates, weights, springs, etc.?

Dave


David Ahrendt

Dave
From my experience playing around with ignition advance curving, I wouldn't recommend just trusting to get the desired result by installing the "correct" or "recommended" springs and weights. It seems to be a bit of an inexact science at best, and a lot of spring tweeking at worst! Even the cam (with the max advance degrees marked on it) can sometimes have been ground to different degrees. Beware. Unless you have a test rig like Bill's (mine is much more Heath Robinson!) you won't know what you are getting until it's on the car. Probably a job for the specialist? If on the other hand you are more of an expert than I am giving you credit for, apologies, and please ignore all of the above!
Bruce
Bruce Mayo

Dave,

I agree with Bruce that reverting to standard spec isn't necessarily the best course, especially if you have tweaked your engine. Even the difference in modern fuels makes the old advance curve potentially obsolete.

If you do want a professional job based on your own engine spec, here's the guy (though he's in the UK):

www.distributordoctor.com

Malcolm
Malcolm Eades

Dave. You need to contact Jeff (Schummer?) about this. He is a long time MG owner who has gone into distributor rebuilding as a formal business. His website is: http://www.advanceddistributors.com/ and several people on this BBS have used his services then posted about the high quality of the work done. In addition, John Twist is in the process of reopening his University Motors, Ltd and should be able to provide the same services.

Les
Les Bengtson

This thread was discussed between 15/04/2010 and 17/04/2010

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