1275 timing marks

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alawrence10360
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1275 timing marks

Post by alawrence10360 »

Is it me or is it bloody difficult to see the timing marks on a Minor ?
philthehill
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Re: 1275 timing marks

Post by philthehill »

Unless you get underneath the front of the engine it is difficult to see the timing marks.

Fit a Declan Burns timing mark kit (use search facility) or paint the marks white.

oliver90owner
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Re: 1275 timing marks

Post by oliver90owner »

I expect that if BL had fitted a 1275 engine to a Minor, the timing marks would have been positioned differently?

Timing marks can be positioned anywhere one cares, within practical common sense.
alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

Yep
I’m going do that
Looking at past posts from Phil I’m going to put the engine at TDC, mark another TDC where I can see it and also 7&22 degrees BTDC
When checking timing at say 4000rpm do you need the vacuum advance connected ?
Declan_Burns
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Re: 1275 timing marks

Post by Declan_Burns »

Here' the timing arrangement.
Regards
Declan
Attachments
Moggy_Spridget_timing_2.jpg
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Timing marks 2.jpg
Timing marks 2.jpg (52.86 KiB) Viewed 2425 times


Regards
Declan
alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

Thanks Declan
Phil pointed me in the direction of your original post
Just need to know if the vacuum advance needs disconnecting when checking the 22 degrees and at what revs
philthehill
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Re: 1275 timing marks

Post by philthehill »

The BMC manual will give the advance at ??? revs with the vacuum advance disconnected and the total advance at ??? revs with the vacuum advance connected.
First set the timing static - then with the vacuum advance disconnected (and making a note of the actual advance obtained) run the engine at the specified revs, then connect the vacuum advance and see what difference it makes. If the difference is as per the manual it is a sure sign that the vacuum advance is working.
Final setting of the ignition timing depends upon the grade of fuel used and outcome of the road test.
The BMC settings were for leaded fuel and are just basic settings - they are not suitable for every engine in use nowadays - no two engines are the same.

IslipMinor
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Re: 1275 timing marks

Post by IslipMinor »

Most A-Series crankshaft pulleys are around 120mm, which proves to be a very convenient diameter for easy timing mark positions. Once you have the TDC mark accurately made, the rest are very simple to do. For a 7° mark, set a pair of calipers to 7mm, and use them to mark the pulley 7mm from the TDC mark. Similarly for 22°, set the calipers to 22mm and do the same.

If you want to be super accurate, use the actual degrees as mm for 1° -9°, deduct 0.5mm for 10°-18°, and 1mm from 19°-40°. If the ignition is set within 1°, that is normally plenty good enough!
Richard


oliver90owner
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Re: 1275 timing marks

Post by oliver90owner »

A pulley of 115mm would give ‘near-as-damn-it’ accuracy as the circumference would be ‘near-as-damn-it’ 360mm, so 1mm equals one degree. Richard’s post is near enough as the real optimum timing Is like Phil says - dependent on other factors.
alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

For the moment Im going to assume my timing is there or there abouts
It runs well enough but I wanted it spot on before tuning the carb
So from what I have read a adjust the timing and test drive until it starts to pink and then back it off
Is that right ?
philthehill
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Re: 1275 timing marks

Post by philthehill »

That is right.

alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

I’ve got an alternator the size of a small planet on my engine so I have had to remove it to gain access to put some marks on
There don’t appear to be any marks on the pulley that I can distinguish so I’ve got the rocker cover off and the plugs out
The cylinder nearest the gearbox is on the rock which I’m assuming is number 4 and I have got the piston nearest the rad at the top as best as I can see
Is this TDC for No1 ?
Also a draft question but does the engine turn clockwise as look from the radiator?
philthehill
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Re: 1275 timing marks

Post by philthehill »

All pulley have a 'V' notch or mark on them to denote TDC. The placement of timing indicator finger depends upon the type of timing cover fitted.

The damper pulley and the non damped pulleys both have the 'V' notched on the front or rear flange of the 'V' pulley groove.
Crankshaft damper.jpg
Crankshaft damper.jpg (47.37 KiB) Viewed 2330 times
You can see the notch of the damper pictured above:-



Looking from the radiator rearwards - the engine turns clockwise.

alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

Cheers
That’s great
The engine is black
Underneath is black and as a resilient can’t see anything
I will have a “feel” now I know what to look for
alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

I’ve looked and felt all around mine and can’t see one
Not sure if there is anything different on a 1275 or my engine in particular
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philthehill
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Re: 1275 timing marks

Post by philthehill »

The 'V' in the pulley should be there.

Here is one for sale on 'e' bay. If you trawl through the photos you can see the 'V' notch.

https://www.ebay.co.uk/itm/Classic-mini ... SwaPhed8mI

oliver90owner
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Re: 1275 timing marks

Post by oliver90owner »

Is this TDC for No1 ?

Ideally you need to make marks on your pulley with the piston rising to the same distance from TDC before and after TDC. Then half way between your marks is TDC. You clearly need a fiducial pointer for this operation.
alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

Well I don’t know about a fiducial pointer but this is what I’ve knocked up
Number 4 is on the rock and number one is at its highest point
Is that right ?
Attachments
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philthehill
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Re: 1275 timing marks

Post by philthehill »

The method shown is perfectly acceptable.
Note the dial gauge positive reading (at least 5mm) before the piston gets to presumed TDC.
Take the engine past presumed TDC to the same dial gauge negative reading.
Back the engine to halfway between the two readings and that will give you actual TDC.
Just make sure that the apparatus for measuring does not move between before presumed TDC and after presumed TDC.
To confirm the accuracy of you reading I would suggest that you measure more than twice. The more times you measure the more accurate the result.
Timing the cam 1.jpg
Timing the cam 1.jpg (370.07 KiB) Viewed 2312 times

alawrence10360
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Re: 1275 timing marks

Post by alawrence10360 »

Ok
I’m I right regarding number 4 being on the rock ?
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