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MG Midget and Sprite Technical - Non starting 1275 with Weber 45DCOE & 45D4 distrib

I inherited a 71 MG midget from my father and other than seeing his expertise on the engine side of things, I'm having to rely on workshop manuals to rebuild the car. I'm at the stage where the engine is in, plumbed in, fitted with a Weber 45 DCOE and a non-vacuum advance 45d4 distributor. Unfortunately, the car refuses to start up and after checking the ignition, I am totally lost on what the problem may be as the Weber should be fully reconditioned. I set the static timing to 7 degrees BTDC using a multimeter on the ignition coil, but strangely, the rotor arm points to the bottom left segment which does not match the 25D4 that was originally on the car which shows bottom right. I've changed the ignition leads accordingly, but I am confused whether this may be the problem or it may be a fault with the carb. Unfortunately, the old distributor isn't in a condition to give it a test. The plugs are sparking on engine turn over and upon removing them, there is a smell of fuel on them indicating fuel is entering the cylinder. Could anyone provide any help? If you happen to live anywhere near Barnsley South Yorkshire you're welcome also to come for a cup of tea to watch me scratch my head! Thanks in advance, Duncan.
D J Ross

I'm just guessing and somebody will tell me that it's got nothing to do with anything, but could the dizzy be 180 degrees out?
Gary Lazarus

Timing may be 180 degrees out. Try swapping plugleads from 1 to 4 and 2 to 3.

There is a scientific way to work out which cylinder is on the firing stroke, but this is quicker!
Dave O'Neill 2

Damn, beat me to it!
Dave O'Neill 2

I think this is an important post and demonstrates why it is neccessary to ensure the basics are righ.

Ignition timing is a definate art and is not guess work so can be set up correctly and forgotten about while other issues are dealt with

With ignition timing you need 3 things to be correct. Spark at the right plug, spark at the right time and finally sparking at each cylinder in the correct sequence.

If you are unsure how to achieve this then follow the instructions on our website to get it correct. Scrol down the page a little to ignition timing.

http://www.mgcars.org.uk/mgcc/midgetreg/ignition%20system.shtml
Robert (Bob) Midget Turbo

Sorry that link did not work too well so you will need to copy and paste it into your browser. Alternatively go to
WWW.midgetregister.com and click on workshop, followed by ignition. Should then sort out the timing issues.
Robert (Bob) Midget Turbo

Also on our website we have details of how to set up a weber. That said even if the weber is set up badly it should start the engine with a couple of pumps of the throttle pedal. If youhave any problems I live in north Lincs and would be glad to sort your problems for you.
Robert (Bob) Midget Turbo

I had a similar problem. Turns out I had the plug leads on wrong. I had checked them multiple times but obviously was wrong. Had a break and a cuppa, tried again and success.

If you've got fuel, then it must be sparks.
Tarquin

Sorry, I meant timing 180 degrees out! see how a little knowelege is a very dangerous thing.
Gary Lazarus

Thanks for your help everyone. I'll try it when I get back home. The thing that confused me was that the distributor, if anything, appears to be 90 degrees out. When it's placed on the bench next to the old unit, the rotor arm is advanced 90 degrees and hence why I had to change the position of all the leads to take this into account. Is this a known difference between the 25 and 45d4 distributor?
D J Ross

This thread was discussed between 15/07/2009 and 17/07/2009

MG Midget and Sprite Technical index

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