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MG TD TF 1500 - Re-orientating Distributor

My distributor is probably oriented in the worst possible position. I'm not worried about the LT lead, as with a Petronix, the connector is protected by a rubber cover. My issue is the cap clips are both blocked. One by the breather pipe, and one by the tach drive.

As I have read that one may install the distributor in any orientation, what steps need I follow to re orient? As I already know which wire is #1, can I just line up the timing notch and arrow when #1 is at the top of it's stroke, re orient the distributor by lifting and turning, re-engage the shaft and tighten the nut (Late TD), and make final adjustments with my advance timing light? Or, am I delusional :-)

Here's a photo of my situation:



L Karpman

All that matters is that #1 fires a the right time. So remove the distributor, rotate the body but keep the rotor cap pointing in the same direction as before when you re-insert. Now your distributor cap will be rotated along with the wires, so you need to move the wires over so that from the outside, they are in their old locations. In other words, #1 wire should once again be over the tip of the rotor cap.

The end result is that the rotor cap and #1 wire are exactly where they used to be, but the distributor body has moved. And of course the order of the rest of the wires remains unchanged, with #1 as a reference.
Steve Simmons

Thanks Steve. Just to be clear, when I lift the distributor I remove the cap without rotating the disributor (I can't remove the cap with distributor installed) and note the position of the rotor tip. Rotate the distributor to it's desired position but keep the rotor tip oriented to the same direction it has been. Reinstall the distributor. Reinstall the cap. The old #1 wire is now moved to where it used to be over the rotor tip, and the 3-4-2 follow suit - correct?

What also concerns me is where I end up after readjusting the timing. I don't want to get the distributor to my desired location and then end up, after rotating it for timing, right where I started from.

I want to END up with the clips at the 10 and 4 o'clock positions, or at 9 & 3. I figure if I rotate it so the clips are at 10 and 4 o'clock, then when rotating the distributor anti-clockwise to re-time I end up somewhere between 10 & 4 and 9 & 3 o'clock. Looking at my picture, what would you suggest the orientation of the clips be when I reinstall the distributor PRIOR TO re-timing?

Thanks again for you help, and I hope I got your instructions right!
L Karpman

LK,
First I would remove your tack drive and get the cover off. When you have removed the cover and MARKED the ROTOR and BODY of the distributor with a felt tip marker. So you can get to this exact relationship position again. You then remove the distributor upwards - which may well move the rotor a tad as the drive gear is dissengaged from the cam gear. Raise the dissy just enough to disengage the gear on the bottom and you can then rotate the body with the rotor whereever you like. Clockwise or anticlockwise. The engine position has not changed so the timing will not be moved. IF you put back the rotor and body with the marks lined up as before. You have now repositioned the body with the rotor of the dissy and have not changed the timing position.
All wired go to the same places you had them before. The only thing that has changes is the gear tooth that is meshed with the cam drive.
You can mesh the gears to get the dissy position you want or as very near to it as allowed by the next tooth mesh. Just remember the dissy Rotor will rotate a little as you reengage the teeth and lower it onto the cam drive gear. So watch the pen marks - that is your correct timing point. They have to be in the same position to each other as when you started this procedure.
Then you won't have to retime the car when done. It should fire right up. However it is always good to check with a timing strobe light if you have one. Or use your ear to get the smoothest running point.
Hope this helps
I am just doing the same thing as I have removed my cam followers and had to remove the dissy to get the tappet chest cover off.
Rod

Rod Jones

Thanks Rd. Problem is, I can't move the tach drive rear enough as its needed rearward movement is blocked by the distributor clip. I tried that last night just to see if that was possible.
L Karpman

LK,
Have you tried to undo the bolt that holds the Dynamo? Remove the belt from the pulley and swing it towards you to give you the room you will need.

Good time to clean & re-grease the gearbox for the Tach too :)

Did you get one of those segmented fan belts suggested by Dave DuBois? It really helps save the rear oilite bearing on the Dynamo when kept slack. Well worth the effort if you don't have one.

Just a thought.

Rod
Rod Jones

I should have mentioned that when using the method I mentioned, you want to rotate the body in 90-degree increments. If you start with the rotor cap at 11-0'clock then it will still be at 11-o'clock when you are finished with the job. But the distributor body will have rotated 90, 180 or 270 degrees. That way, assuming you started with one spark plug lead directly over the rotor, in firing position, one plug wire lead will still be located directly over the rotor cap, in firing position. But it will be a different lead than before, so you need to move the wires 90, 180 or 270 degrees to compensate for the cap and body moving.

If you rotate by an amount not divisible by 90 then you will have to re-time the engine to get the timing back where it was before you started. I would definitely check the timing when done because you may not get the body moved a precise 90-degrees.
Steve Simmons

I don't have easy access to a distributor at the moment, but I'm not so certain that there are 4 or 8 eight teeth on the cam gear. I suspect that it's six. I'm not so sure that you can plan on movements in 90° increments. I could well be wrong. Bud
Bud Krueger

Perhaps it is me who has this all wrong??

I do not think you have to rotate the dissy in any particular degrees of movement. Any position where you can get the teeth to engage between the cam and the distributor will be fine. The only major point to remember is if you made a mark on the body of the dissy with a corresponding mark on the rotor to give you an exact relationship position and they are in that same position when the distributor is back in. Wherever you rotate it to. It will be the same timing position that you had before.
If the rotor was positioned at the location for Cylinder No1 ignition wire. Then that wire is still going to go to cylinder No1 after you have re-positioned the Dissy. Nothing has changed but the rotational position of the distributor. The only proviso is you do not change the position of the Engine internals while doing this.

If you start this procedure with the engine at TDC on No1 and index mark the dissy at this point. Wherever you rotate the distributor to with the index marks in the same position you will not have changed the timing.

Will soon find out - when I reassemble my Cam Followers and Rockers this weekend and put the distributor back in. I plan to also move it round a tad to help with ignition wire alignment. So they don’t cross up so bad.
Rod
Rod Jones

Rod,

If you set your timing mark to TDC and the rotor is pointing the #1 plug when you pull the distributor out of the car, when you reposition the distributor to allow you to have easy access to the clips, the rotor needs to be pointing at the same spot it was when you removed the distributor IF you want to use the same plug wires. Yes, they'll have to be moved around the cap to maintain the correct firing order but many owners have them cut to length and you'd have to stretch #1 across the cap if it was now in the #4 position.

Gene
Gene Gillam

Thanks all you guys, and thanks Rod for the dynamo suggestion. Yes I have a segmented belt. This re-orientation project will have to wait a bit until I am satisfied that the carb issue I posted on has been resolved. I believe it has, but until I can test the car under driving conditions I won't know for sure.
L Karpman

Gene,
I totally agree with the comment that the wires will possibly need changing - if the move is radical enough to prevent them from reaching their original locations after the move. That's not a problem in my case as the move is just a small one (36 degrees). Existing wire length will suffice OK.
I was just concerned on the comment that the change needed to be in 90 degree increments?
As I understand it, you should be able to move the distributor to any tooth mesh position as long as you ensure the rotor and the distributor body stay the same relationship to each other.
My distributor has 10 teeth on the bottom. So I guess it is possible to rotate the dissy in 36 degree increments - As long as you rotate the rotor (Shaft) by engaging the correct tooth.
The timing relationship with the unmoved engine (important) will remain the same as it was. Once you line up the marks you made originally. Done by rotating the body of the distributor to suit and locking in place.
It is to be noted that as you lower the Dissy into the block, the rotor will rotate a tad as the gear on the end engaged the scroll gear on the cam. You then need to rotate the distributor to line up your marks correctly. The cap with the wires marked 1, 3, 4, and 2. Will go back (if they can now reachļ) to the same positions as before.
This has always worked for me the past - not that it gets done that often.
The attached pic shows some of the movments possible - that maintains the timing position as it was originally. 4 of the ten possibly positions.

Rod.


Rod Jones

Rod: Are you and Steve at odds here? he says,"remove the distributor, rotate the body but keep the rotor cap pointing in the same direction as before when you re-insert." You say, "They have to be in the same position to each other as when you started this procedure." I'm confused.
L Karpman

The only reason I recommend rotating in 90 degree increments is because there are 4 wires, so rotating 90 degrees will prevent the need to mess around with timing too much. If adjustment is needed it will be very minor. And leaving the rotor pointing in the same position and then moving wires to match keeps the wire lengths correct. I like my wire routing clean and neat, so it's just a convenience thing. There are several ways to skin this cat, this is just the way I've done it on my car.
Steve Simmons

Steve. I think it's MY interpretation of your term "same position." If you agree with the marks and alignment that Rod shows in his photos, OK. I was interpreting "same position" as if currently my rotor is pointing to #1 at the 10 o'clock position, when viewed from the top, and when I rotated the distributor to it's new position I put the rotor back to 10 o,clock and connected the #1 lead there, then it is different than Rod's. That is what is confusing me.
L Karpman

I think LK we have made this way more complicated than it really is. Sorry to have caused any confusion and I am certainly not at odd with you Steve...

When you reposition the distributor and set it so the rotor mark still points to the mark you made on the distributor body. The cap will have moved round with it, as it is keyed to the body. Therefore the No1 post is still the No1 post and the No1 wire will go back to the No1 plug. None of that will change as indeed neither will the timing.
A problem might occur if you have cut the ignition wires to be short and direct (and neat) with the distributor in its previous position - Then they may not all reach their respective plugs with the distributor moved round. No big deal with that, just make a new wire for the short ones if you have to. My Distributor only has to rotate about 36 degrees (one tooth) anticlockwise and the wires actually fit better that way anyway. Everything is more direct without crossovers.
Im sorry if I have not explained this very clearly. The pictures show it better if you imagine the cap in place and the wires going to the same plugs. You have changed nothing but the position of the distributor. Its internals and the engine internals are all in the same position. You have mealy changed the drive point where the distributor connects to the camshaft. This can be in any one of ten positions due to the ten teeth on the drive sprocket. When you move the sprocket round a tooth - the rotor goes with it via the shaft. So the body has to go round with it to keep the timing position the same.
I hope this explains it a little better LK. ļ

Rod

Rod Jones

I tried all positions on mine, two positions I couldn't get the clips open without forcing them and scratching the paint on the push rod cover and the third position, which was 180 degrees put the + wire in the back! I put my distributor in it's original position and installed a new belt slightly longer to move the generator out further and everything is fine, no issues! Problem solved. PJ
Paul S Jennings

Not at all Rod, your method works just fine. I was only offering one of many solutions, the one that I prefer. As noted in my first reply, the only thing that matters is that #1 fires at the right time. Whether the #1 wire is in its original position or a modified position makes no difference. Rotate everything (body, rotor, plug wires) together, or rotate just the body and leave everything else where it was. It makes no difference to the running of the engine!

Larry, you have it right. I left my rotor at 10 o-clock and put the #1 wire there. Rod's method moves the rotor and #1 wire to a different point on the clock.

I always cut my own wire from bulk, and if you do this as well then you can make them whatever length is required to fit any position of the distributor cap.
Steve Simmons

This thread was discussed between 10/09/2014 and 11/09/2014

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