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 M-Type Ignition Timing
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mharnden

United Kingdom
4 Posts

Posted - 28/06/2020 :  18:18:15  Show Profile
Hi. My M-type has an auto advance distributor (Lucas DJ4A) and on inspection the previous owner has marked the 1/4 (assume TDC?) mark on the flywheel with a spot of paint.

How can I perform a static check of the engine ignition timing? I was expecting to see two flywheel marks.? The second mark would identify the correct angle for the spark before top dead centre (TDC).

Any help is appreciated.

Matt



Keith Durston

United Kingdom
496 Posts

Posted - 28/06/2020 :  18:39:59  Show Profile
Matt, on the brass plate on the side of the rocker cover it will tell you the ignition timing. Your paint spots show where TDC on numbers 1 and 4 are so all you need to do is to set the paint spots at whatever the degrees are (I think before TDC) and check that the points are just opening on number one lead. If something doesn't look right take out number 1 spark plug and carefully put a small screwdriver in the hole to confirm that the piston is at the top. Your engine will have been apart many times in its life and if I remember correctly it is possible to reassemble the flywheel in any one of 4 positions so the original marking on it may no longer be right!!!!! Good luck.
Keith
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PreWarMG

Australia
347 Posts

Posted - 29/06/2020 :  09:42:42  Show Profile
M1524 has a Minor fan fitted, so I was able to mark the crankshaft pulley at TDC, and at 10, 20 & 30 BTDC.
I set the timing at TDC (full retard on lever), and advance half way once started, then full advance once the oil pressure reads 40.

We are here for a good time, not a long time !.
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PreWarMG

Australia
347 Posts

Posted - 29/06/2020 :  09:44:36  Show Profile
The marked pulley.





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Keith Durston

United Kingdom
496 Posts

Posted - 29/06/2020 :  10:09:35  Show Profile
Matt, Having been back in my garage this morning and looked at the brass plate it says exactly what Tony (PrewarMG) has said. I'm sorry my memory wasn't up to it last night when I thought it was before TDC. Blower states that at TDC the distributor should be fully retarded and the points just opening.
Hope this all helps.
Keith
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mharnden

United Kingdom
4 Posts

Posted - 29/06/2020 :  19:06:09  Show Profile
Thanks everyone for the responses.

The only issue I see is that the distributor on my car is auto advanced as the distributor comes from a later car (J2?). If I statically set the points opening at TDC then perhaps this isn't correct and I (like you) would have thought that the points opening should be before TDC.

I do have the original manual advance distributor which I plan to rebuild and install at some point in the future.

I also do have a strobe light so I could check the timing dynamically, but again I need to know the correct position/mark to check on the flywheel.

Any advice is appreciated!
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PreWarMG

Australia
347 Posts

Posted - 30/06/2020 :  22:57:37  Show Profile
Here is another option for checking the valve and ignition timing if you have no front pulley.

The alloy collar is held in place with blue tac, and marked every 5 degrees. You will of course have to read the timing chart in the shop manual in the other direction.





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PreWarMG

Australia
347 Posts

Posted - 30/06/2020 :  23:04:57  Show Profile
Matt, You should set the static timing at TDC. Points just opening - connect a test bulb on the points, rotate the dizzy to the point where the light goes out & fix the dizzy there.
Connect your timing light & start the car. You should be able to see the advance working as you increase the engine revs.
Safety Fast

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Deess

France
67 Posts

Posted - 01/07/2020 :  06:52:41  Show Profile
If it has 1/4 stamped,, there's a chance the other marks are also there somewhere on the rim...? white dot will help strobe it when running///
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mharnden

United Kingdom
4 Posts

Posted - 01/07/2020 :  12:45:14  Show Profile


Great! Could you possibly post a photo of the timing chart that you refer to?

Edited by - mgmog on 02/07/2020 11:03:29
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PreWarMG

Australia
347 Posts

Posted - 01/07/2020 :  22:58:49  Show Profile
Hi Matt, This is the timing chart from the Owners Handbook. As you can see it details the valve AND ignition timing.
If you study it you will understand that it describes the timing at the flywheel, where the engine turns anti-clockwise so the 30 degrees IGNITION advance is to the left of TDC.
If you read the timing at the front of the engine, where the engine turns clockwise, you have the 30 degrees IGNITION advance to the right of TDC.
This chart also confirms where you should set the static timing (TDC), and maximum advance is 30 degrees before TDC.
Timing at the front of the engine is so much easier than trying to view the flywheel marks.
Ignore all the valve timing - this was changed in later M-Type's and in the 12/12 models.
Safety Fast - Good Luck





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PreWarMG

Australia
347 Posts

Posted - 01/07/2020 :  23:02:31  Show Profile
Here is the later valve timing as described in "Maintaining the Breed".





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mharnden

United Kingdom
4 Posts

Posted - 02/07/2020 :  10:40:42  Show Profile


I canít thank you enough for this information! I had seen the timing chart in the handbook but had assumed it was referring to valve timing! I have also ordered the Thornley book to have a read. Thanks again!

Edited by - mgmog on 02/07/2020 11:04:05
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mgmog

United Kingdom
317 Posts

Posted - 02/07/2020 :  11:06:37  Show Profile
Hi Matt
No need to reply with quote sometimes, a quick reply or reply to topic keeps the thread a bit clearer without duplication.
Best.

Rich Stott
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Blue M

United Kingdom
1051 Posts

Posted - 04/07/2020 :  12:37:29  Show Profile
Moving the marks up to the flexible drive coupling is useful if you don't have an pulley.



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PreWarMG

Australia
347 Posts

Posted - 05/07/2020 :  13:09:57  Show Profile
A very practical solution. It would be nice to buy the discs with appropriate marks and a pointer in the kit. Hmmmm......

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