MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Small springs in 25D distributor

Hi,
I noticed that the shaft in my 25D distributor
wobbled. It seemed that the cause was that one
of the spring holding the weight (for mechanical
advance?) was damaged. I checked Moss motors
catalog. Unfortunately, the spring was not
available. Is there a way to find them? Do I
have to by a whole replacement distributor?
Please advise.
Junji
Junji Sugisawa

The spring shouldn't cause the shaft to wobble. It could/would cause an incorrect advance curve. A wobble in the shaft is probably caused by a worn bushing in the distributor housing. You may want to give Jeff a call at Advanced Distributors.
http://www.advanceddistributors.com/

Clifton
Clifton Gordon

I am with Clifton concerning the shaft.

If you are looking for the springs, don't try the Moss MGB catalogue but the Moss TR3/4 catalogue. There they have listed a spring set for the D25 there, that contains a number of differend springs that fit the MGB dissy too.

Ralph
Ralph

I'm with Clifton regarding Jeff at Advanced Distributors. First, your distributor needs to be re-bushed. Second, you need new springs - but WHAT new springs? Jeff will set your dizzy up with springs that will give you the best mechanical advance curve for today's fuels and for whatever other engine mods you have or anticipate.

FWIW,
Allen
Allen Bachelder

Hi Clifton, Ralph and Allen,
Thank you for your prompt advice! It was really
helpful to know that the wobble wasn't due to
the spring. I'm going to contact to Advanced
Distributors. Also interesting to know that
Moss lists the spring only to TR3/4 catalog.
Junji
Junji Sugisawa

BTW, don't forget that the two springs are different thicknesses and lengths, and the thicker is *supposed* to be loose on its pins and the other tight.
Paul Hunt 2

Hi Paul,

I think longer spring should be loose and the shorter on
should be tight, is this correct? I noticed the shorter
spring in my distributer was damaged. The shorter spring
was not holding the weight tight. I initially thought
that was a reason why the distributer shaft was loose.
I used word "wobble", but that might be misleading,
the shaft seems to have few degree of slack in rotating
direction. The shaft does not shake. Is there
possibility that simply replacing the small spring
fix the problem? Or should I contact to Advanced
Distributors to be safe?

Thanks,
Junji
Junji Sugisawa

Junji,

the D25 was used on B's up to 1973, if i remember it right.
Your dizzy should be 35 years old by now and it is a good idea to contact Advance Distributors for an overhault or exchange. It is not only the shaft that can wear, the advance mechanisem and it's bits are also prone to wear after a long time of use and you have to dismantle everything and check it before you know what needs fixing.
Changing some parts that look o.k., does not realy help, you need to know the engine data and you should be able to use a test bench for checking and setting.

I run tests with a number of D25 and D45 dissys on my test bench and would not agree that a dizzy that can be installed to your enginge would automatically be the right one.
Talk to Jeff, it will safe a lot of time and money and give good results to use his service!

Ralph
Ralph

If the rotor i.e. the top part of the distributor shaft has *rotational* free play then that is indeed caused by a slack 'initial' spring, and is very common on old distributors. Whilst sending it away and getting it rebuilt and recalibrated to the original specs can be done at a price, it is arguable that those original specs are irrelevant with today's fuels. If the distributor is otherwise sound I'd be tempted to just tweak the spring to take up that slack (that is what the likes of John Twist do anyway with the springs that *are* available).
Paul Hunt 2

Hi Ralph and Paul,
Thank you for your comments. Yes, my distributor's
shaft has rotational free play. Otherwise, it seems
solid. I'm going to play with the initial spring
first. If that does not work, I'll send my distributor
to Advanced Distributors. I have more time than money
(in relatively speaking manner), so I would like to
try less expensive solution first.
Thanks,
Junji
Junji Sugisawa

Junji,
What year is your car? More often than not, the AMOUNT of advance is worng, as id the rate of advance and the primary (light) and secondary springs (heavy, loose fitting) are both fatigued substantially. Installing a new primary spring will help with idle for sure BUT installing the wrong spring can possibly give you a hesitation or pinging. Don't get me wrong - anything's going to feel like an improvement over what you have now. A rebuild will cost far less than a replacement though, and work more reliably!
Jeff Schlemmer

Hi Jeff,
I (actually my friend) noticed this distributer
problem when we were searching for cause of
my car not idling well. The short spring
was damaged, so it was not tight. I think that
exactly matches to your comment. My car is 67 MGB.
Thank you for your advice.
Junji
Junji Sugisawa

The primary in the 40897 distributor is VERY light and cannot be corrected by tightening it with a pair of pliers. Its just way too light. Contact me via email and I can work out a great solution for you - cheap, maybe just temporary, but truly functional.
Jeff Schlemmer

Just the other day I drove a B equiped with a 123 ignition. I was very impressed by the low down torque, seemed to be a lot more than other B's. No pinking either. Engine probably standard, since there was a "roof rack" on the bootlid.

If I was to spent a lot on my dizzy, I would consider 123. However I'm a diy type, so that makes it a different equation.

All imo,

Laurens.
Laurens CGT

'Engine probably standard, since there was a "roof rack" on the bootlid'

Eh? Run the logic behind statement that past me.
Paul Hunt 2

I'm with Paul - there's a "roof rack" on my bootlid but my engine is certainly not standard. Even my distributor is recurved!
David Overington

It was the overal appearance of the car (and the owner) which led me to believe that he would like to spent time in the country site having a picknick out of the suitcase transported using his boot rack. I don't see any other use for the device (and drive a GT anyway) ;-).

I greet you all smoking a pipe and keeping myself warm in my tweed jacket (not) ;-)!
Laurens CGT

This thread was discussed between 10/03/2008 and 18/03/2008

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now