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Mini A series engine - timing woes

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I'm calling on some advice from those that know the Mini A series engine a bit better than I do.

Mrs Flash owns a 1974 1100cc Mini Moke that we bought a while back. There are signs that the engine has been apart before and it’s always suffered with an intermittent misfire that new plugs, points and condenser didn’t solve. I figured if I ignored it long enough, it might go away, but sadly not. The misfire got steadily worse and then last week it got to the point where it died and it was a battle to re-start it. When it did eventually start it sounded really sick. So I figured it was high time that I investigated the issue.

As a first step I popped a timing light on and noticed that at idle the timing mark was intermittently jumping around. I then pulled the distributor out and discovered a huge amount of play in the distributor shaft. I decided to invest in a new 45D electronic distributor rather than having my tired old 29D refurbished. The new distributor arrived yesterday afternoon and I set about installing it this morning. It's at this point that things started to get interesting.

When I went to re-fresh the timing marks on the flywheel with a bit of white paint I discovered that the dull painted marks placed by a previous owner are not actually on the correct flywheel factory markings. I decided to ignore these home-made marks and proceeded to use the factory flywheel timing marks to setup the engine at the correct position for cylinder 1 using the procedure outlined in my Moke repair manual (cylinder 1 at TDC on compression stroke with factory TDC flywheel timing mark aligned with the pointer).

I then installed the new distributor and it's at this point that things became really interesting. My repair manual states that with cylinder 1 set to TDC the key at the bottom of the distributor should align with the slot in the distributor drive shaft and the rotor should point at roughly the 1 o'clock position. In my case with the new distributor snuggly fitted into the distributor drive shaft slot the rotor points at the 3 o'clock position.

This, together with the presence of the home made timing marks on the flywheel has got me wondering whether at some point in the past the gear at the end of the distributor driveshaft has been set a tooth out.

Does this sound like a reasonable assumption ?

Thanks for reading

Picture of Moke as everyone likes pictures.

$_20 (2).JPG

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I assembled one of these A engines a few months back, your description of dizzy position sounds correct....

If it hasn't been replaced the chains in these will be getting really slack now, they can jump teeth.

Put it on TDC, pull the cover off and see if the crank/cam marks point to each other.  I cant recall the exact position but the crank key should sit in a particular reference to this also (it may have stripped the key).  In the Haynes manual

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Two things:

1, the flywheel can slip on the crankshaft rendering the timing marks useless. 

2, the intermediate dizzy adapter drive ( the bit that has the gear on the bottom and slot at the top) can be installed incorrectly.. 

2 is more likely than 1, and given your description sounds like it could be a tooth out. Which means you run short of timing adjustment on the mounting slot. 

 

The above suggestions from @RUNAMUCK and @nzstatoare definitely all good, I would start with a tdc vs crank position check because it's easy, and sometimes crank pulley removal can suck with the engine in the car, bearing in mind you cannot 100% trust flywheel marks. You could also add some fresh tdc and 10 degree marks to the crank pulley area as a rough timing light guide. 

 

EDIT: if the chain slackness is of concern perhaps watching the dizzy rotor or rocker gear whilst turning the motor clockwise and then anticlockwise slightly would give you an indication of timing gear wear. 

Edited by mjrstar
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I had an a15 with a cam once. I had to utilise the secondary adjustment to get the timing right. I suspect because it had been dialed in, it had moved the datum of the timing gear on the cam or some such.

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Fellas, thanks heaps for the suggestions and advice. Armed with the extra info provided I'll poke around a little more later today and will let you know what I discover. Thanks again.

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Thanks again to everyone who provided me with guidance.

I can confirm that the distributor drive shaft was one tooth out.

I flipped it a tooth and now the factory timing marks line up. Took it for a quick spin and it is like driving a totally different car. No more miss fire. Pulled a plug after the drive and noticed it's running a bit lean, so tweaked the mixture a wee bit. I'll monitor the plugs for a few days in case it needs a bit more tweaking.

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