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MG TD TF 1500 - Dwell Angle

I've been quietly going through the tuning routine on the TF1500.

First stage was static timing followed by strobe timing a 3,000rpm. Typing correction fluid in the notch is a great help!

This was the first time I used a dwell meter. The main observation was that I could not get a steady reading, either at tick-over or 3,000rpm. It did give regular clear readings howewver around 54 in amongst all the noise.

So, my questions are:

1) should the meter give a steady reading and if so what suggestions for achieving this, or is it a sign of a failing coil, condenser or some such.

2) presumably the dwell angle is decreased by opening the points (they are currently at .012), and increased by closing them. Is this correct, and how sensitive is it to small changes.

As usual many thabks for your help and knowledge.

IanB
Ian Bowers

Ian, I can only help on #2. Scan my recent post here about engine cutting out and you will find the resolution was my point gap! It was about .016. Don't ask me how it got that way? I changed it to .014 and the cutting out went away immediately! So, yes, it is VERY sensitive to small changes!!

About 6 weeks till you-know-what,
Ed
efh Haskell

I'll address #1 - the steadier the better. If there is a lot of movement the distributor bearings are probably worn, and you could profitably have the dizzie rebuilt. In the US, Jeff Schlemmer of Advanced Distributor offers excellent service and re-configures your weights and springs for optimum performance with modern fuels. I can't help you with a UK rebuilder.

Tom
t lange

Ian, are you using a digital or analog dwell meter? I've seldom seen stable dwell readings on digital dwell meters. Perhaps I just haven't seen a good one. Bud
Bud Krueger (TD10855)

Hi Ian - when I purchased my TF1500, one of the items that was totally worn-out was the distributor.

One area of weakness on the 1500 distributor and the later TD/TF distributors is the fit between the upper "bowl" of the distributor and the shaft that houses the spindle and the associated bushing (it is actually a bushing rather than a bearing).

A worn bushing or a loose upper "bowl" can cause that dwell to jump around.

As Tom mentioned - Jeff is our expert over here. Might be worth sending it over and having it rebuilt.

My distributor was so worn out (and the bowl so loose) that Jeff was unable to do anything with it. He said he couldn't believe that my car even ran!

I have since purchased a correct on on Ebay and was very fortunate to have it be one in excellent condition.

Good luck Ian,

Jeff

Jeff Delk

Ian,

Fear not - all is repairable! Dwell angle is around 55 degrees, new sintered bronze shaft bush can be inserted, and if bowl is loose 2BA grubscrews can be put into tapped holes in the bowl to restore grip. Check out advance /retard springs and pivots, repair/ replace as needed.

See Archives re static timing - forget the existing TDC notch and advance around 1/4" on the c/s pulley to make new mark.

Good luck,

John
J C Mitchell

Thank you all for the helpful and intelligent answers.

It is a digital dwell meter, so I will try it on the TDII which has a distributor rebuilt by Jeff Schlemmer and see if the 'noise' is still there. If not it will go over to him this winter.

I did set the static advance around 5deg as the starting point, and then noticed with the strobe that the advance at 3,000 rev was a little erratic. There was another few degrees advance when the revs went up to 4,000.

I think I will reface the points (again) before gapping to see if there was any spiking/erosion on the face.

All seems to be pointing towards a rebuild!

IanB
Ian Bowers

J. C. Mitchell Your description of 2BA screws to fix a loose bowl on a distributor interests me. Can you make a sketch of just how they are to be installed. And put it on the thread.
TIA.
Bob
Bob Jeffers

Ian,

I'm on the same path you are and I bought a 2nd-hand analogue dwell meter a couple of weeks ago. It showed my setting of the points with a feeler gauge gave 35 degrees, so I closed them slightly and got 58 degrees. To answer your question, it is sensitive to very small changes. The running was better after the change, so it does seem to make a difference. The reading was absolutely steady on the meter, BTW, but there is a new dizzy on the car.

- Tom.



Tom Bennett - 53TD 24232

I have an old dwell meter, but haven't used it in 40 years....
Where should I connect it to read???
Thanks
Edward
E.B. Wesson

Edward:

Mine was a two-wire meter and I have a +ve earth TD.

I simply clipped the -ve terminal of the meter onto the connection from the coil to the distributor (no need to disconnect anything, just piggy-back it onto the terminal on the coil) and the +ve to a suitable ground.

Mine also reads RPM when you flick the switch on the meter to do so.

I'm assuming for a -ve earth car, you'd connect the opposite way around. I also understand there are 3-wire meters, but I can't recall how they are connected. I do know there is information in the archives on how to use one of those

- Tom.

Tom Bennett - 53TD 24232

Tom
Thanks ...I also have (+) earth, and my meter is two wire....
I'm going to try it.
Edward
E.B. Wesson

Hi Bob,

Thanks for your interest re. fixing loose bowls. I can't send a sketch unfortunately, for despite being computer literate for around 12 yrs, my scanning need is very limited, and I'm still relying on my old Epsom 760 printer, sans scanner!

I've not had a need to do the fix myself, but the method is to insert 4 Allen type grub screws axially into the 'narrow' lower part of the bowl, which then takes up the play. I understand that originally the bowl was squeezed onto the shaft housing, but it is hard to replicate this without a specialised clamp/press. It might be better to start with smaller grub screws, eg 4BA, to allow for tapping errors etc, and later enlargement/correction.

I don't know where I picked up this tip, but I see no reason why the axial screw approach wouldn't work; anyone tried it?

Cheers,

John
J C Mitchell

Hi Bob,

Here's a picture of one side of my distributor after being repaired by Jeff at Advanced Distributors.

Dave



Dave Runnings

Thanks J C Mitchell and others. I have a dist. repaired by Adv. Dist. and I have another that is loose. So I will investigate the placing of screws to correct the problem with the loose one. Then I could get it repaired by Jeff also.
Thanks anyway,
Bob
Bob Jeffers

Hi Dave,

It seems that Jeff uses the same method I referred to! Thanks for info.

Cheers,

John
J C Mitchell

Ian-
The UK's equivalent of our own Jeff Schlemmer is "Distributor Doctor". Click on this: http://distributordoctor.com/distributors.html
Stephen Strange

I have bought red rotor arms from him, and it is certainly cheaper than shipping in to the UK from the USA (I am not sure whether they actually originate from the 'Doctor' or not).

Come the winter and time to avoid the salt on the roads, he will be the first port of call to see if this is a job which is in his remit.

Many thanbks

IanB
Ian Bowers

This thread was discussed between 06/08/2011 and 09/08/2011

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