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MG Midget and Sprite Technical - SimonBBC Dizzy / electronics advice?

Hi All,
As my mk iii midget failed to start and was not sending a spark around- despite running ok last weekend- I remembered the PO's comment that the dizzy was knackered so I bought from SimonBBC , a new 25D dizzy with the electronics on board, a red rotor arm and a new coil - I thought "right replace it all one time so its done & then forget about it" I bought from Simon BBC as I had his electronic ignition in my old mini & it was fine ( but I didnt fit that one)
Ok connected everything up and left dizzy in so I can dynamically time it.
Now - I THINK i'm at number 1 TDC .
I have checked & double checked my electrical connections are right.
I left it then and thought I would post this - IF ....( !) I'm not at TDC on number one - whats the worst thing that could happen- could I knacker the new electronics at all?
Could I knacker the engine ( which did sound lovely WHEN it ran!)
I don't have any more time to play with the car before friday, so would welcome all of your comments.
cheers & thanks
colin
( getting there......slowly)
colin frowen

Probably no damage at all although I have occassionally seen the foam type air filters catch fire when an engine spits back when cold and timed incorrectly. This is unusual however.

That said it is so very easy to time an engine correctly that you should have no doubt when you do it.

To determine number 1 TDC we have 2 methods

1 remove plugs and turn engine to what you believe to be TDC on number 1. Now rotate crank pulley 1/2 a turn anti clockwise (this will place the piston of number 1 and 4 at the bottoms of their stroke) Now place finger over plug hole and turn crank back to TDC mark clockwise. You should have felt alot of compression when you do that test compared to the same test done on number 4 cylinder. f number 4 feel like it is more compression then you are at TDC number 4 or 360 degrees out.

2 remove rocker cover and with engine on what you believe to be TDC number one you should be able to feel clearence on the tappets of number 1 cylinder. the tappets on number 4 cylinder will have no clearence.

Robert (Bob) Midget Turbo

To get TDC (compression stroke)on number 1, turn the engine to align pulley marks. Take No1 plug out and with a fine, longish screwdriver, check the piston is actually at the top. You'd be surprised how often the TDC pully mark is "off". If it is off then re mark the pulley.Take the rocker cover off and If BOTH rockers have clearance (can "rock"), that is TDC at top of compression stroke. If one valve is open (exhaust), then rotate engine another turn.
When you have got TDC positioned you can then position the rotor arm opposite No 1 plug lead. That should allow the car to run and then you can set dynamic timing with vacuum pipe removed and bunged.
Firing 180 dg out won't do any harm to either but best to set up as above.
Firing order 1,3,4,2.
Allan Reeling

This thread was discussed on 17/01/2012

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