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New Engine Wont Fire

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#1 IainNeon91

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Posted 25 March 2013 - 11:44 AM

Hi all, on behalf of my brother. He fitted a 1275 Sprite engine into his mini yesterday and with going over everything it wont fire up.

There is a couple of things we might think that is preventing this, one being the earth strap from the engine bay to the coil isn't connect up because it's completely shot. The other being the timing/static timing.

There is fuel going through and a very good spark, firing order is believed to be correct.

Electronic ignition on an A+ engine.

Any thought's will be very helpful!!

Many thanks,

Iain.

#2 IainNeon91

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Posted 25 March 2013 - 11:45 AM

He has also had the battery on charge over night. So will be trying that this evening.

#3 Dan

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Posted 25 March 2013 - 12:02 PM

You don't earth coils, this will stop your engine working.

If you have spark and you have fuel and its turning fast enough then check the timing, and if the timing is right check the fuelling.

#4 IainNeon91

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Posted 25 March 2013 - 12:10 PM

Where does the earth strap in the engine bay connect to? I have an earth going from my servo to my coil, it's been there ever since i bought my mini :wacko: Or is this just an earth for the servo?

It seems to be turning fast, yes. So we will look at the timing.

Many thanks,

Iain.

Edited by IainNeon91, 25 March 2013 - 12:11 PM.


#5 cal844

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Posted 25 March 2013 - 12:26 PM

the earth strapS go on the engine steady bars(they do on my 89 mayfair at least) to ensure you hae a good connection clean the shoulder on the bolts and the steadies until nice and shiny metal.

#6 Dan

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Posted 25 March 2013 - 12:31 PM

If it's earthed to a bolt holding the coil, it's not earthing the coil. Servo to the coil bracket is an odd place to put it!

#7 IainNeon91

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Posted 25 March 2013 - 12:43 PM

If it's earthed to a bolt holding the coil, it's not earthing the coil. Servo to the coil bracket is an odd place to put it!

Yeah it seems odd now, thinking about it! But i also have an earth on inner wing....?

#8 Woreign

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Posted 25 March 2013 - 12:44 PM

It could be that your distributor is 180 degrees off. Either reindex the dist. drive, or change the plug wires around. This happened to my Mini when I first got it. The rotor wasn't in the expected position...

#9 IainNeon91

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Posted 25 March 2013 - 12:56 PM

so if i put cylinder 1 to TDC and the rotor arm isn't pointing towards no. 1, this could mean it's 180degrees out?

Also i know when doing static timing of points, that after you have no1 cylinder at TDC you should turn the dizzy until the point's just open. Whats this step when you have an elect. dizzy??

#10 IainNeon91

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Posted 25 March 2013 - 01:06 PM

the earth strapS go on the engine steady bars(they do on my 89 mayfair at least) to ensure you hae a good connection clean the shoulder on the bolts and the steadies until nice and shiny metal.

Would the engine not start if there isn't an earth strap on the engine steady?

#11 lrostoke

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Posted 25 March 2013 - 02:13 PM

If there engines spinning on the starter then theres a good earth already to the engine..

If the rotor arm is pointing to roughly 2 oclock with the engine at TDC for No1 cylider (piston at top, and you can wiggle both rockers nearest rad)
If you keep the dizzy loose have somebody crank the engine whilst you rotate the dizzy back and forth, should hit the sweet spot where it kicks in..then set with a strobe

Edited by lrostoke, 25 March 2013 - 02:13 PM.


#12 IainNeon91

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Posted 25 March 2013 - 03:11 PM

I pulled the car forward in first gear, so piston 1 was a TDC. Took off the dizzy cap and the rotor arm was pointing at 7 o'clock ??

#13 midridge2

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Posted 25 March 2013 - 03:33 PM

you need to check the rockers to make sure its on the firing stroke.

#14 IainNeon91

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Posted 25 March 2013 - 03:38 PM

you need to check the rockers to make sure its on the firing stroke.

I already had the rocker cover, but what is the 'firing stroke' ? Sorry for the noobie questions :shy:

#15 Dan

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Posted 25 March 2013 - 04:26 PM

It's a 4 stroke engine, it has 4 strokes per cycle which means 2 crank rotations per cycle per cylinder. Inlet, compression, ignition, exhaust. So each cylinder has two different times when it is at TDC per cycle, one at the end of exhaust and the start of inlet (during an overlap period when both valves are operating) and another one at the end of compression and the start of ignition when it has to fire the spark plug. You need to set the timing to the correct TDC in the cycle, during the first one both valves are operating so you won't be able to feel any slack in either rocker. During the second TDC, the right one to fire the plug, both valves are closed so you will be able to feel slack in both rockers.





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