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MG TD TF 1500 - distributor timing/firing order

Hi All

It has been a while since I have asked any questions as the car has been running really well. Unfortunately the manifold gasket blew out this weekend and I replaced it today but when fired up it had a small miss. So....pulled all plugs and cleaned and reset them then pulled the distributor cap and checked everything and ensured gap was correct on points. While doing this I did notice that the plug wires sequentially go to the plugs ( 1 TO 1, 2 - 2, 3-3 AND 4-4) so I set them for a firing order of 1-3-4-2 and it wouldn't even start. Checked again and while it should have been correct I had to set them back to 1234 to get it to run????? While it runs just fine and has lots of power (all relative) what have I done wrong that would result in this???

Thanks
Brian
Brian Smith (1950 TD3376)

The rotor turns counter clockwise. One is in the front of the engine.
Dave Braun

There are TWO positions when the timing mark is at TDC and the piston is at the top of its stroke, end of exhaust and end of compression. The rotor should be pointing at the lead to the piston at the top of the compression stroke.

So, if it isn't firing correctly rotate the leads from the distributor cap round 180deg.
Ian Bowers

Thanks for the comments. The problem is that the engine runs just fine...but it shouldn't. Once I switch the wires to the 1-3-4-2 configuration it will not run.

Starting at the front of the engine (#1), the plug lead comes from the #1 position at the distributor, this same pattern follows up to #4.

This one has me stumped but I am thinking that I should just leave well enough alone. I run a steady 40 lbs oil pressure and 180 degrees, only just touching 190 on a very hot day and pulling up a long hill but immediately goes back to 180.

Dave, the rotor is marked with an arrow and I have confirmed TDC on compression so have allowed for this.

Ian, as above.


Brian
Brian Smith (1950 TD3376)

Hi Brian,
Could you post a picture of your dizzy and leads in its running condition.I can't think of any way it should run 1 2 3 4.
Ray TF 2884
Ray Lee

Brian, if you really want to sort this out more info will be needed...whether the problem is with the car or how you are viewing it..because the conditions, as you describe them, cannot exist. perhaps i misread your post, but if not, the car cannot run with a firing order of 1-2-3-4. regards, tom
tom peterson

Just came in from the garage and can confirm that position 1 on the dizzy goes to #1 cylinder, position 2 goes to #2 etc. Tried changing it to 1-3-4-2 and it turns over but does not fire, replaced to the way I had it and it runs smoothly.

I know, it is impossible but it runs that way so I am just going to leave it. If someone has a possible idea I will gladly listen. I have been working on MGB's and MGA's since the late 60's so am familiar with the concept but am stumped as to why this engine is different. I tried taking some pictures but they just aren't clear enough to post so hopefully my description will work. The dizzy turns counterclockwise and the rotor has an arrow.

Thanks for the responses.

Brian
Brian Smith (1950 TD3376)

Brian, it's really nothing mystical. Essentially, you have timed the engine 180 degrees out on the timing mark. Then you inserted the distributor 180 out.
If you pull your distributor out and reinsert it so that the rotor is pointing to cylinder #4 you will now be in a 1-3-4-2 configuration. Bud
Bud Krueger

Brian,

Something is wrong...

You either don't have an MG engine in your car but rather an engineering marvel since NO four cylinder engine that I'm aware of can use, or has ever used, a 1, 2, 3, 4 firing order OR you're looking, doing, interpreting or otherwise misconstruing what you're looking at.

Please post a photo of what you have and a video of your engine running...I'm truly interested since I've searched the internet and cannot find a single *inline* 4-cylinder engine that, because of balancing purposes, uses anything but 1,3,4,2 or 1,2,4,3 as a firing order.

http://www.howacarworks.com/basics/the-engine-how-power-is-created
Gene Gillam

Like Bud said ...or you have a very strange crank & cam! Can't imagine that unless there is a mount for a paint can on it somewhere. ;-)!
David Sheward

If a special cam and stock crank, wouldn't the crank have to rotate 360 degrees for 3 to fire after 2, and for 1 to fire after 4?? That would be a really shake, rattle and rolling motor. The crank would have to be very odd also? Custom made? Anything is possible, but I would like to see pictures and video also!
George Butz

To dispel any thoughts to the contrary, it is an early mg td engine and is totally stock in configuration. Cam was replaced a couple of years ago (stock) and crank is the original. I like the comment that Bud has made and will look into this but I have put a few thousand miles on this car with the engine in this configuration so my interest is purely because it is "different" than the others and shouldn't run like it does.

As for a video....I will explore the technology and see if I have what it takes and then try posting to YouTube. May have to rely on my kids to help out. Took it on a run last Sunday, three hours each way on the highway and will be doing another run on Saturday to the best British pub on Vancouver Island and perhaps in BC. This is a lunch run so not drinking and driving!

Brian
Brian Smith (1950 TD3376)

Gene is correct.
It just depends on the distributor rotation, & if #1 is @ the front or rear of the block.
Len Fanelli

George ,
"unless there is a mount for a paint can on it somewhere"

As in paint mixing machine!
David Sheward

Perhaps the distributor cap is a special one (for dummies...), with some internal wiring that changes the sequence, so that the outside connectors run in the sequence 1-2-3-4, even though the rotor follows the required 1-3-4-2 order.

Jesus
J Benajes

Brian.. I bet that it is a flat cap with the wires coming out the side. The internal wiring of that type cap can lead one down the garden path of frustration.
Sandy
DARNOC31

Might the plug wires have those plastic markers that snap right on the wire to indicate which cylinder it goes to??? It would give the false indication of a 1-2-3-4 firing order??? (the marker for cylindar #3 fell off)

STEVE WINCZE

Sandy, it is an old style cap with wires coming out the top.

Steve, only markers on wires are tape with numbers I put on.

I tried a different camera today and have attached a pic. Hopefully it is clearer than the ones I took the other day.

Brian

Brian Smith (1950 TD3376)

That shows 1-3-4-2.
D. Sander

Brian

Just checked the latest image you posted and if what I am observing is correct the firing order with the rotor turning in a counter clock wise direction is 1-3-4-2.

Current HT lead installation is a hotchpotch and should be reconfigured by going back to basic principles;

Ensure the points gap is set correctly,

Rotate the engine so that No 1 cylinder is on the compression stroke at TDC,

Remove all plug HT leads from the cap,

Remove the distributor and fit the cap, mark the distributor body and cap where the HT lead connector in the cap for No 1 cylinder would be at or towards the front of the engine, ensure that the cap attachment clips will be accessible and the points electrical connection will not foul the tachometer drive when you refit the distributor in the engine,

Reinsert the distributor so that the rotor button is pointing towards the mark placed on the distributor with the points open,

Temporarily install the distributor cap and commencing at the mark placed on the cap fit a suitable length HT lead that reaches from the cap to No 1 plug,

Complying with the COUNTER CLOCKWISE direction of rotation of the rotor and the firing order 1-3-4-2 select suitable HT lead lengths to connect between the cap and the plugs in that order,

Remove the cap and rotate the distributor body in a CLOCKWISE direction observing when the points are fully closed. Then very slowly rotate the distributor COUNTER CLOCKWISE observing when the points just begin to open,lock the distributor in this position.

Refit the cap ensuring all HT leads are connected, engine will start and run, final engine timing is a process of what ever settings you normally adhere to.

Very difficult to explain this process in words I hope it is decipherable and you obtain a positive outcome.


Graeme









G Evans

looks like 1342 to me as well. that explains why the engine runs. problem solved. regards, tom
tom peterson

Hi Brian,
unless you are after concourse points, leave it alone.
It works and you will never have your tacho drive short out the ignition as many others have.
Very few things on my car are as it left the factory I just use it and enjoy it.
Ray TF2884
Ray Lee

1-3-4-2. Looks to me like the LT connection is about 2:00, no way it could short out. Leave it alone, drive, and enjoy. George
George Butz

IMHO: Only possible problem I see there is that #1 & #2 wires appear to be a bit on the short side. Dependent on how good you plug caps are could pop-off with engine vibration?
If that hasn't happened ...drive it ...definitely 1342 from what I see.
David Sheward

Brian,
Just to be clear, what numbers did you put on the wires?? Is the picture that you posted taken with the wires positioned when the car won't run or when the car runs fine???

SPW
STEVE WINCZE

I agree with everyone else...that shows 1,3,4,2, not 1,2,3,4.

If that's the way that it runs the best then I'd skip Graeme's advice (as good as it is) and leave it alone - or possibly replace the spark plug wires with some a slight bit longer.
Gene Gillam

Sorry guys, I agree that I should leave well enough alone and continue driving it but I have attached another photo that shows it more clearly. I would love someone to explain what is shown.

Brian

Brian Smith (1950 TD3376)

Brian,

I'll try.

The #1 sparkplug wire on your distributor cap is located back near the vent for the tappet cover. The sparkplug wire is going to the the 1st sparkplug in the engine (front).

Continuing counterclockwise from there, the next sparkplug wire is going to the #3 sparkplug (3rd from front).

Again, ccw from there the next sparkplug wire is going to the #4 sparkplug (rear of engine).

Lastly, still ccw, the sparkplug wire is going to the #2 sparkplug (2nd from front).

The firing order is thus 1, 3, 4, 2

By the way, this is a picture of a different engine than the 1st one you posted.

Gene
Gene Gillam

Actually the same engine, just a different angle. Thanks for your explanation.
Brian Smith (1950 TD3376)

OOps... same engine but the first one was an older picture. My mistake, I have since changed it to stock configuration for tappet cover and rocker cover.
Brian Smith (1950 TD3376)

Hoax?
Mort Resnicoff (50 TD-Mobius)

No Hoax, I drive this car a lot in the Summer. The restoration process can be found at;

http://members.shaw.ca/briantsmith/

I didn't realize that I had two pictures of the dizzy side of the engine and took the first one I came to.

Brian :>(
Brian Smith (1950 TD3376)

Brian, I don't see what the problem is. Both pictures you show have the firing order as 1342. Do you have a picture of it actually running with the "1234" order?
Cheers, Hugh
H.D. Pite

I have a TD so I don't know if this applies to a TF but it looks like the dizzy is just 180 degrees about and so maybe the rotor is also 180 about or something to compensate.
Jud
J K Chapin

Brian,
Almost all the distributors I have seen on the T series look like this. When you insert the distributor into the engine block you have a choice of any (360 degrees) orientation you choose. The plug wires are usually like mine and are sized for this orientation.
Yours is the same firing order but twisted about 120 degrees CCW.
At this point it is your choice. Leave it alone if it runs well or reset it as described above.
Mort

Mort Resnicoff (50 TD-Mobius)

If you are re-setting the distributor and/or cap orientation there are several olocations worth missing.

One places the rearwards clip against teh fume pipe from the tappet place and makes it difficult to re-latch.

The second places the low tension lead close to the same pipe and can short.

The third pplaces the low tension lead close to the reduction box on the end of the generator, again leading to short and a failure to fire properly.

Looking at the engine I prefer the oprientation with the clips at 10 and 4 o'clock, and the low tension lead at 7 o'clock.
Ian Bowers

Mort

Thanks for the picture. My leads do not follow yours. Mine do not go 1-3-4-2 like yours so I will check out like Bud says as I have definitely got something wrong. We drove 3 hours down Island and 3 hours back today on the highway and it ran great but I would like to get this straightened out now. Your picture was worth a thousand words!!!

Brian
Brian Smith (1950 TD3376)

Think we need a new picture showing cap & plugs.
Fist pic sure looks correct to me.
Send one ...a bit hard to tell what cyc they are going to.
David Sheward

Brian,

Even though your photo looks different your leads do go 1, 3, 4, 2.

Read what I wrote and follow your leads.

Gene
Gene Gillam

Brian, the orientation of the distributer is immaterial provided the wire leading to #1 cylinder is firing near the top of its compression stroke (which it must be for your engine to run). If you incorrectly label the rear cylinder as #1 and the front one as #4 you will still need the same sequence of 1342.
How about a picture of the distributer that you drove down island with? I looked at my calender and it is not April 1st!(LOL)
Cheers, Hugh
H.D. Pite


Set the # 1 8the front piston) on top of its compression stroke, set the distributer in the disired position. Then the lead to # 1
cylinder is where the rotor is pointing.
Then you set the other leads CCW (seen from the top. The Lucas info on direction is seen from the underside of the distrubiter.

Thoralf Norway TD 4490
Thoralf Sorensen (TD4490)

Brian,

From your picture that you posted [#15 back up the page] - you show the correct firing order - hence you engine runs OK

1-3-4-2 Distributor turns in the anticlockwise direction as seen from above.

You are fine as is. Should not be an issue.

Rod.

R. D. Jones

Can't get any clearer than that, Rod.
Gene Gillam

Whoa, did I have a major seniors moment!!!! We put a lot of miles on the TD in the past few days and I left it sitting in the garage with the bonnet sides up while I had to travel in my other mode of transportation for a meeting.

Today, with clearer mind and fresh eyes I looked again, what do you know 1-3-4-2.

I apologize for even starting this thread but I would like to thank everyone who responded and maybe....just maybe, it might help someone else. I have been working on and restoring MG's since the late 60's so should know a lot better and wish I could explain why I didn't see it before. Maybe my navigator should be worried...

Brian
Brian Smith (1950 TD3376)

NO worries Brian,
At least for me, it was good exercise!

I'm an "audio guy" so spent much of my life counting to "2". (check 1-2, check 1-2)
Mainly we do this because everyone knows on "3" you lift. Heck with that, I'm too old to lift.
(wow ..I can still count to 4!)

Just do me a favor ...don't come up with something where I have to count beyond 15 ...I run out of digits.

Cheers ;-)
David
David Sheward

This thread was discussed between 17/07/2013 and 23/07/2013

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