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MG TD TF 1500 - Advance / retard

My wife says men can't multi-task but I'm having a good go at it. As well as sorting out the brakes, I'm still trying make progress on getting the tuning right and I'd like some advice. Forgive the newbie questions but I'm still near the bottom of the learning curve. I've had a good look through the archives but I can't find quite what I'm looking for, in amongst all the varied threads.

1. Am I correct in thinking that retarding the ignition means rotating the distributor clockwise? If it does, I've been wrong in my assumptions so far, which might explain why I haven't sorted things out.

2. I've got a timing light which has been indicating TDC when the orientation of the distributor body shows the rotor arm is just before 11 o' clock. However, the engine runs dog rough at that setting and stalls when I advance to 10 o' clock. It's only when I twist the distributor clockwise, through 12 and then on to 1 o' clock that it picks up revs and starts to run better.

3. Even at that setting, it's not right, with some rough running and missing still evident. However, I can't rotate clockwise any further, as the chest cover breather pipe gets in the way.

4. I notice in the archives that I can allow for more adjustment by lifting the distributor, so the drive gear disengages, and then rotating it anticlockwise before re-engaging the drive gear, so I'll have a go it that (encouragement from this BBS permitting) tomorrow.

5. If I do that, what reading should the timing light be showing when the timing is right, please? The current reading is 35 degrees with the distributor at the fullest retard I'm able to get (i.e. the 1 o'clock setting at which the engine runs best). It also means I'll have turned the distributor through 60 degrees of arc (between my "reading" of TDC at 11 o'clock and the 1 o'clock when it revs best) which seems a lot of adjustment to me.

I thought I'd set up the distributor correctly by finding TDC and then checking when the points were about to open, but I'm also wondering if I'm just at the wrong segment of the arc.

Thanks again to you all, in advance (no pun intended).

- Tom.



Tom Bennett - 53TD 24232

Tom, IMHO you need to put your timing light away and dig up a plain old test lamp. TDC is when the pointer on the timing cover is in line with the notch in the crank pulley. Unfortunately, this occurs twice per engine cycle, i.e., when cylinder #1 is at TDC and when cylinder #4 is at TDC. The most direct way of determining which is for #1 is to remove the valve cover and see which indication matches up with valves #1 and #2 being loose. At that point the rotor should be pointing at the spark plug wire that is connected to plug #1. You can lift the distributor up and rotate it all you want to relocate the plug wires. Regardless, the engine is about to fire spark plug #1 to power cylinder #1. Now you want to connect your 12v test lamp to your distributor low-tension terminal. Pull the coil high tension lead out of the center of the coil to assure that the engine isn't going to start. Now turn on the ignition and look at the test lamp. Loosen the distributor clamp and rotate the distributor CCW until the lamp goes out. Now slowly rotate the distributor CW until the lamp just comes on. Lock it down. You are now timed to TDC.
Your engine should run reasonably well at that setting, but you will probably;y want to advance the ignition. A common setting is to adjust the timing, using a timing light, to 30 dregrees of advance at 3000 rpm. Good luck. Bud
Bud Krueger (TD10855)

Tom,

For the time being, forget about the timing light. Turn your key off, remove your #1 spark plug, then use your crank handle to turn the engine around while your wife puts her finger over the spark plug hole. She'll feel pressure building when you're approaching the compression stroke for #1. Look at your pulley and the pointer on your timing chain cover...when the markers line up you'll be at top dead center. Remove the distributor cover and make sure your rotor is pointing at the #1 spark plug cable and make sure your points are just opening.

Now, put everything back together then slightly loosen the bolt holding the distributor body in place and start the car. With the car idling turn the body of the distributor either clockwise or counter clockwise until the engine starts to speed up (normally clockwise on our engines). If the engine continues to speed up as you turn the body of the distributor but you hit the rocker cover then yes, pull the distributor out, reposition it and check again that the rotor is pointing at #1 when you're on the compression stroke and try again. Final adjustment is when the engine starts to slow or run ragged after its been speeding up...turn the distributor body back the other way until it runs smoothly then tighten it down.

In my humble opinion the only way a timing light will help you is if you have a variable light. If so, set it at 30 degrees before top dead center (BTDC), start the car and rev the engine above 2000 rpm. Adjust the distributor body until the mark on the pulley and the pointer on the timing chain cover are aligned...you're now in correct alignment and timing.
Gene Gillam

tom, the distributor shaft and thus the rotor turn counter-clockwise. if you rotate the distributor body CLOCKWISE you are advancing the timing. which i guess that means from your number one bullet point that you have been doing it correctly.
from the point you are working from in regard to car knowledge i would not pull out the timing light right now. i would find the compression stroke for number 1 cylinder, align the timing mark for TDC insert the distributor body in the block with the orientation you want in reference to interference with breather pipes and tach reduction drive, etc. see which distributor post the rotor is aligned with. that is now cyl number 1 plug post. you can either reposition your ignition leads to this new distributor position with the knowledge that the firing order is 1-3-4-2 in a counterclockwise order OR slide the distributor back out and rotate the distributor drive gear to a position you think when you reinsert the distributor it will align the rotor with your number 1 spark plug wire. this process may have to be repeated several times to get the rotor in the correct position. if you elect to realign the rotor by sliding the distributor back out and rotating the drive gear, it does not mater if you rotate the drive gear clockwise or counter clockwise.
once you get the distributor in the block, rotor pointing to number 1 cylinder plug wire i suggest hooking up an ohm meter across the points and when they first open tighten the distributor in this position and go out and have fun with your car. it will start well set like this per the workshop manual and will run well. after you get more familiar with the car you can tweak the timing. i think the guys are using 30 advance at 5000RPM
just my two cents. regards, tom
tom peterson

I think we were all writing at the same time. Thankfully we all agreed for the most part...main difference was the rpm at which to use the variable timing light. Since full advance is somewhere in the neighborhood of 2K I don't see any reason to go much above that but faster won't hurt.
Gene Gillam

Gene, you might want to take a looksee at http://www.ttalk.info/Tech/Advance_curves.htm Bud
Bud Krueger (TD10855)

gene, i believe you. i don't have a variable timing light so i pulled that info out of an archive post. thanks for the info. regards, tom
tom peterson

This thread was discussed between 25/07/2011 and 26/07/2011

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