All fixed - Number 1 plug wire position on the distributor

Is the number 1 plug wire position on MGB distributors always the same in relation to, for example, the top side dist. cap clip? Does it depend on the distributor installation position? Are there two 180 degree opposite possible positions due to the distributor being able to insert in one of two positions.....or are there 4 possible positions during installation?

Also, if the plug wires were in the correct order (1,3,4,2) but off by one position on the cap, will the car even start? Or perhaps, if off one position clockwise or counter-clockwise, would it start one way but not the other?

Thanks,
BH

The distributor drive can go in multiple ways. Its geared.
The distributor will go into the drive only one way (offset dogs).
The cap can only go on correctly (ears and cut out for electrics) only one way.
Wires can go on in 16 combinations, only one is correct, but will start in a couple and run poorly.
RS

the disttributor can only be installed in the correct position---not 180 out--the cross key is offset to one side of the shaft. the engine will start and run poorly if one or more plug leads are positioned incorrectly--put it in and adjust to TDS rotor (if you have one)should pe pointing to #1. Good luck . safety fast

In answer mto your question about how many ways it will go in: The dizzy itself will onlt go in ONE way. If you look closely at the bottom of the dizzy, you'll notice that the key in the bottom is offset ever so slightly offcenter.

BUT, if the drive gear has been removed, that will go in in any position 360 degrees.

YES, it does matter WHERE they are.

YES, most MGBs have the number one cylinder firing position at about 1 to 2 o'clock position.

This will never change UNLESS someone has disassembled the engine OR the dizzy drive gear.
So, BH, rather than going any further, lets first determine WHAT is wrong with your car, and then we can go forward.

Just tell us what its doing.

There are ways that we can determine whether or not your car has been put together the right way. Its pretty important that it is put together the same way that the manual wants it to be done. Some people on here will argue this fact, saying it doesn't matter, but when you are off on assembly, and then you correct it by moving the dizzy drive gear, or the dizzy itself, then adjustability can be hampered, diagnosing things can be harder for the novice.

One quick way to determine if everything is right, is to get the number one piston at TDC on Comp Stroke, and see where the dizzy is, and if it corresponds to the dizzy cap.

Tell us what your car is doing, and we'll go from there. Get your digital camera ready to post some pics.

B

The car was running great.......73B roadster. ......however:

After having the heater valve dump antifreeze all over the distributor the other day the car ran fine after closing off the leak. However, the next morning it ran awful so I pulled off the dist. cap and cleaned out the antifreeze that had gotten inside. It's been sitting for several days with the cap off drying out.

Unfortunately I was careless when I pulled the cap and didn't take note of the number 1 wire position. I installed it at the 1 o'clock position, which is just to the right of the distributor cap clip, which is pointing straight up. From there I went counter-clockwise with the wires.......1,3,4,2.

The car is running........but rough. I tried moving all plug wires one position clockwise and the car wouldn't even start. I haven't tried moving them 1 position counter-clockwise to see what would happen.........thought I'd ask for advice here first.

That's why the issue came up. Learning more about how the car works along the way would be a nice side benefit to solving the probably minor problem.

BH

If you did not remove or even move the distributor, then assembly will be correct if rotor is pushed on all the way and cap
is located correctly. Set the engine at TDC and confirm rotor is pointing at #1.
Also check and clean points.
RS

Ooops..........sorry...........it has a Pertronix ignition.
BH

Always carry some moisture displacing spray like CRC or WD to spray on /in cap,,wires ect.
in some climate situations the cap will sweat on inside also.

Bill sound like your drive gear is 180 out. It happens alot on rebuilds. Try starting the number 1 plug at the 8 o'clock position and see what you get.
Bill

ya what Bill says is possible, if and only if, the yahoos putting the car together put the drive gear in, in the wrong position. This DOES happen because when the follow the manual, they don't look closely at the drive gear and they don't realize that it is in upside down, or when they install it, the #1 piston is not on the compression stroke, it would still be all the way up, just not on the comp stroke. It happens!!! Like Forest says!!!!

NOW, this is assuming they actually installed it properly, just off 180 degrees. Since you moved it forward one, and backward one, and neither worked, it would make sense that its 180 out, BUT, that's NOT 100% for sure. Who knows what the yahoos did.

What we usually see here though BH, is that YOU are making a mistake on the firing order. Go make sure. Its really easy to confuse the wires sometimes, Follow them closely.

Now, If this doesn't work, then you're gonna have to find TDC on the comp stroke #1 and then install the wires accordingly.

ALL of this is assuming that you didn't fry something with your little rain shower. But, lets make sure of everything before going down that road.

Can you post a couple of pics of the wires, the cap, and the rotor.

B

Get the distributor in. Turn the crankshaft until #1 piston is at TDC and wherever the rotor is pointing is #1, arrange the wires in the cap from that point to match the firing order. This is not always correct but it will work every time, no muss, no fuss.

I bet you just bumped the dizzy body around when you cleaned it.

The drive gear don't jump out and turn around all by itself when it was running fine before the leak.

Isn't the rotor going to be pointing at either the #1 or #4 position depending upon whether the #1 piston is in the compression or exhaust stroke when the engine is turned to TDC?

I could pull the valve cover and when both front valves are closed with the timing mark showing TDC, that should put the rotor at the #1 firing position....correct?

BH

That's correct BH, but it's easier to connect the leads as JD said.

If it runs, you've got it right, if it doesn't then it's just a question of swapping leads.

Saves having to lift the rocker cover and risk leaks on refitting.

Well everyone.....thanks for the input and lesson on the ignition system.

This morning I started by draining the coolant (wish my radiator had a drain plug). I replaced some some overdue hoses and put in the new heater valve from the Beehive. Other then the mess on the floor it was a pretty easy project.

When done I warmed up the engine to check for leaks. It was still up on the front ramps and still running lousy.......would barely idle.

I turned it off, did a little cleaning up, started the car again (still barely running) and backed it off the ramps. I managed to get the choke at a point where it would just idle so I let it stay there so it could warm up and I could check for leaks.

After about 5 minutes of cleaning up I noticed it had started to run smoothly. Can't say why.......just all of a sudden I had my smooth running engine back. Perhaps it just finally dried out enough, or perhaps as I say below the WD-40 had something to do with it.

I will say that I learned a little from this experience. First was that I'll side with the guys that say not to spray WD-40 on the distributor components. I did that before seeing some of the other comments. First I fear it is flammable and second it is a water repellent coating, which means it might leave enough material on the parts to cause resistance to the spark getting to the plugs.

Second, thanks to all of you I now have a much better understanding of what is going on in that part of the ignition system. It is weird that the engine suddenly started to run right again........but hey..........it's an LBC !!!

Thanks for all the input!
BH

Glad you got it sorted.

When my heater valve dumped, WD-40 got me home. But what happened next is the lesson I took away from this.

After pulling and replacing the cap a few times, it wouldn't run at all. Problem was I had inadvertantly dislodged the little graphite button up inside the center of the dizzy cap. This is the electrical connection between the top of your rotor and the connector and ultimately the wire out to the coil.

Live and Learn!