MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Static Timing Rebuilt Distributor

Time to install a recently rebuilt distributor (with new pertronix Ignitor) in my 1976 1500. I took a shot at dropping it back in place in the same orientation as when I removed it, but the timing is so far out that that it won't start. So, I need to understand the process of static timing better. While I have read about this in the archives, there are some basics that have been left out that I need to know. What I am hoping for is a series of steps that include all of the simple things that I might not know having never done this. I understand the firing order (1,3,4,2) in counter-clockwise sequence and the relationship to the spark plug wires. I'm less sure of the importance of selecting the correct starting point on the distributor cap (does it matter which terminal is designated No. 1 as long as the wires are connected to the plugs in the correct order?). I also need to understand the process of turning the engine (by wrench, in gear or out, etc.) to get to the starting line. I'm fine with dynamic timing once I get the rough work done. Thanks.
Steve
S. G. Mauer

my friend Dave fitted a Pertronix thingy to his VW Camper, it immediately refused to start even though it was fitted in-place as if using the points

We had to swing the dizzy about 30º or 40º to get the engine running

and when I fitted the MG Metro dizzy to my car I had the same thing happen

try turning the dizzy clockwise (I had to) 20º or 30º as a base setting

It doesnt matter IMO where the sparks happen with regards to the cap, just that the sequence is right from the firing point

I think the Haynes book tells you enough about the due process of setting up from the start, but I think that without the opening and closing points to operate a test light you would be better doing it "on the swing" as described above

hth
Bill

< I took a shot at dropping it back in place in the same orientation as when I removed it >

Are you sure? Have you tried rotating it 180 degrees?

R
Richard 1979 1500

I can echo Bill's comment above; when I replaced the points in my Mallory with a PerTronix a few years ago, I began by carefully marking the position of the rotor by placing a small straightedge along the rotor, and making a small pencil mark on the rocker cover.

With the PerTronix unit in place, I worked with the distributor until the rotor was aligned very near its previous position. And of course the car refused to start. Turns out the relevant bit here is that the firing point of the PerTronix is different from the firing point of the points, relative to the rotor.

So I was able to rotate the distributor until I was close enough for the engine to start. I then fine-tuned it with my timing light, and all was ducky.

Best of luck, by the way! My engine hasn't missed a beat due to ignition faults for a long time now.

-:G:-
Gryf Ketcherside

The fastest way to get the timing close is to pull out a plug, reattach the lead and lay it on the block,stick your finger on the spark hole and crank the engine with the ignition on. Swing distributor till the 'pop' and spark are coincidental.
f pollock

Two things important to timing correct, both extremely simple.

Right time
Right place (plug)

Right time is the first.
Turn the engine so that the TDC notch on the front pully is at the TDC mark/pointer (or if you want to static time it then set it to the correct static timing mark. If you simply want to start the engine and time it dynamically with the engine running then TDC will start the car easily).
Remove the lead from the dissy cap that is connected to the coil (sometimes refered to as the king lead, should be called the coil lead) Place the bare end of this lead to almost touching the engine. About 30thou would be good you will see the spark jump this gap shortly! With the dissy loose and the ignition switched on rotate the dissy by about a total of 90 degrees back and forth. during this rotation you will see a spark jump the gap between the coil lead end and the engine. The dissy needs to be set at a point that the spark occurs when the dissy is rotated CLOCKWISE.

So with the time now correct, now the place needs setting

Remove rocker cover and check the rockers 1 and 2. If they both have free play then the engine should be firing on number 1 plug and rockers 7 and 8 should both be tight with no free play. IF rockers 1 and 2 do not have free play and thus rockers 7 and 8 do then plug number 4 should be firing.

Once you have established which plug should be firing remove the dissy cap and check which post the rotor arm is pointing towards. This should be pointing to the post with the firing plug connected to it.
With that established look at the dissy cap from above and if number 1 was firing then anti clockwise from number 1 should be as follows 1 3 4 2. If number 4 was firing then it is simply 4 2 1 3.

I hope this is easy to follow

Robert (Bob) Midget Turbo

Steve. Organize an assistant and a timing light (stroboscopic). While doing this, put the battery on the charger so you start with a fully charged battery.

Connect the timing light to number one cylinder and the battery. (I assume you will be using the more modern style of timing light having the three connections.) Have the assistant crank the engine over on the starter while you observe the timing marks and rotate the distributor. When you are somewhere between twenty five degrees advanced and zero degrees, the engine should start. Fairly wide range of timing when all you are doing is starting the engine and allowing it to idle. When the engine starts, have the assistant run the engine up to the proper speed used for dynamic timing for your car and set the timing exactly.

If the engine is not wanting to start, move the distributor until the timing is showing 10 degrees before top dead center (BTDC) on the harmonic balancer. This will have the timing in a position that it will start while you diagnose and correct the cause of the not starting problem.

Much easier to use this method, when using an electronic points replacement system. Fully as easy as the older style of static timing when using points. Dynamic timing is about all that I use anymore, including on initial start ups.

Les
Les Bengtson

On the positive side today started out around 20 degrees and warmed up to over 50 degrees. Less positive was the fact that I still haven't been able to start the midget. I was able to get the timing close by pushing the car in gear until it was around 10 degree BTDC (Timing pully mark at 10 degrees BTDC with rotor arm pointed at plug no. 1 location on distributor cap). I have good spark (coil lead to engine block verified), but can't seem to get more that a few rough just about to start sounds followed by a loud backfire. In fact the most consistent thing it is doing now is backfiring. I have rotated the distribtor 30 or 40 degrees in each direction without success. Does backfireing (loud explosion type sound out of the tailpipe) provide any clue to my problem? Thanks as always.
Steve
S. G. Mauer

If you have a timing light, you should be able to see where the timimg is whilst cranking.
Dave O'Neill 2

Sorry. I didn't mention that I did use a timing light to verify that the timing was at least in the neighborhood (the light showed about 280 rpms while cranking so it was strobing slowly, but the timing notch was visible roughly in the center of the marking scale). I also heard sounds that I think might have been weak attempts at out of sequence detonation--like when an engine is missing, but much more feeble. The backfiring was anything but feeble --loud and sharp.
S. G. Mauer

Double check you have the correct lead for No1 it sounds to me that you may be 90deg out - Don't ask why i say this ! the sound you describe brings it all back.

Richard.
richard boobier

Moving the dissy backwards and forwards to start an engine is silly. You must simply time it CORRECTLY as described above. Once this is done then you know that is then not the problem.
Also you should set the plug leads CORRECTLY again as described above and it will also not be a problem.

However listening to your description you seem to have these wrong. And if so it is generally because the firing order has been set clockwise and not anti clockwise in which case cylinders 2 and 3 will need reversing.
Robert (Bob) Midget Turbo

Steve. My website, www.custompistols.com has a tech article on ignition timing you might find useful. It starts with setting the timing marks after watching the intake valve open and close, then follows through on how to static and dynamic time the engine. If you follow through in a logical sequence, you will find out if you have the distributor oriented properly. I agree with Richard and Robert--something sounds like it is out of sequence. Make sure the distributor is fully seated before doing anything else. Then start with watching the valves open and close and go from their. Takes a short time to do the job properly.

Les
Les Bengtson

Well, how many voted in favor of the distributor being 180 degrees out? As soon as I quit being stubborn the problem was solved in minutes. I struggled to get my mind around the idea that the rotor arm could be aimed either at the firewall or at the radiator (180 degrees apart) while the TDC notch on the balancer was at the TDC marker. In fact, my results were similar to flipping a coin and having heads come up ten times and getting tails on the eleventh. Ten times the rotor pointed one way and on the eleventh it pointed 180 degrees. I then changed the spark plug leads accoringly and it fired right up. Timing from there was routine and the car is running great. Thanks again for the help.
S. G. Mauer

Hi,

Getting in late on this but, just bought a Pertronix Flamethrower Distributer with the Flamethrower Coil.

Same as the original posting, cranks won't start. Kinda like my wife at times. No spark, have 12 volts to the coil. Plug wires are on the cap clockwise 1,3,4,2. I have set engine at TDC, rotor to #1 plug but nothing.

What do you mean by rotate the Dist 180 degrees, turn in over? It sounds crazy but I'm desperate. Pull it out and turn it upside down?

Help!
DG Haynes

DG,


My understanding is there are 2 ways to rotate a dist. 180 degrees

1. pull the dist. out of the engine rotate the rotor exact oppisite from pointing to spark plug number 1...(aka. the rotor is pointing at Number 4 lead on the dissy cap.)

2nd way

from the dissy cap to the spark plugs

1-4
2-2
3-1
4-3

in other words the firing order is 4-2-1-3

I have never had to do this, I have no experiance with it, but from what ive read, thats my understanding

good luck

Prop
Props Black Hole

I think that what Prop is trying to say is:
at the distributor-
1/ take the plug wires at 12:00 and 6:00 (like a clock)
and swap them
2/ take the ones at 3:00 and 9:00 and swap them

This works easily for the plug-in style caps-
for those with side-exit caps just take the plug wires off of the sparkplugs and swap #1 with #4 and swap #2 with #3. You won't be able to hook them all up this way (at least one will be too short) but will tell you if this was the problem.

Bill
Bill Masquelier

What do you mean by no spark? Is there no spark through the coil wire and plug wires? If not, then you have a problem with the low tension circuit.

I installed a Flame Thrower distributor and coil 3 weeks ago and found that the (+) and (-) posts on the new coil were opposite from the original coil...make sure you have the red lead from the dist. connected to the (+) post and the black lead to the (-) post.

A quick test to verify the distributor is sending a signal to the coil, is to use a test light...connect the aligator clip to battery negative and touch the point of the probe to the (-) post on the coil, crank the engine and if the light goes on and off ( it will flash quickly ) then the distributor is sending the signal to the coil correctly.

Also make sure you have good crimps on the terminals on the ditributor to coil leads...I've had bad terminal crimps wear me out while troubleshooting more than a few times.

If you have spark through the coil wire, but not the plug wires...there is a problem with the cap or rotor. I know the cap and rotor are new, but stranger things have happened.

Good luck

Dave
DL Rhine

If anyone wants a simple explanation of the ignition system on Spridgets and how to set the timing from scratch then use this link
http://www.mgcars.org.uk/mgcc/midgetreg/workshop.shtml
Then simply click onto Ignition system
Robert (Bob) Midget Turbo

DL,

Nothing to the coil using your test. I also tested to see if I had a resister, getting 12v on the coil.

Put the old coil on and nothing.

Switch plug wires as suggested, nothing

Can not turn rotor 180 degrees, drive doesn't allow.

I think it's all about the missing spark?
DG Haynes

Bench tested the coil and distributer. Both work fine on the bench.

That is when I put it all back on the engine and found that I have a blown fuse on the white wire.

Replaced the fuse, blows as soon as I put the positive on the battery terminal. Now tracing the whites to see where the short is. This is a brand new wiring harness.
DG Haynes

Electrics are not my specialty in no way shape or form...

but I know the white wire goes under the dash to the tach an back out of the tach and back across to the other side where the fuel pump splices in at the USA passanger side front of the door area, But honstly, I dont remember if the white wire was fused or not...I want to say no, but I wont bet 2 dime to prove im correct, it seems like it also went to the key switch...Agian i wont be betting 2 dimes, and a penny to prove it


But I do know for a fact it does go to the tach and the fuel pump
Props Black Hole

Starting to make a little more since now. Once you correct the short, the distributor and coil should be a snap.

Like I said, I recently installed a Flame Thrower dist. and coil...installation time about 30 minutes including setting the timing.

I'm very pleased with the results...engine runs alot smoother, seems to have more power over a broader RPM range...I definitely recommend this upgrade!

Dave
DL Rhine

This thread was discussed between 04/02/2009 and 09/09/2009

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.