AN sells something called an "IGNITION TIMING PLATE CHECK TOOL" part # 13.1769

Status
Not open for further replies.
I have used it.

It is a disc that you double side tape to the rotor. It is marked with TDC and 20 30 and 40 degrees before TDC.

When you mount the outer primary case cover the 20 30 and 40 markings allow you to check the accuracy of the degree markings on the primary cover.

Mine was out by 2.5 degrees. You can see on the photo the outer 30 deg mark for example coresponds to 32.5 on the primary case scale.

Ok that didn't work cause it says file to big. Unfortunate. Let's try sgain
 

Attachments

  • AN sells something called an "IGNITION TIMING PLATE CHECK TOOL"  part # 13.1769
    20200509_213637.jpg
    98 KB · Views: 567
Last edited:
during my tri-spark installation and timing, I double checked my factory marker. installed a degree wheel and piston stop, found TDC (several times for repeatability), set 28°, and checked the factory. my case mounted indicator read 30°. two degrees probably doesn't mount to a hill of beans unless you're looking for that racer's edge. just wanted to know that baseline reading - not something i'll be checking too often.
 
I have one, haven't used it yet. My timing scale is missing/damaged and I'll use the tool to properly align a new one.
 
has anyone bought this? I can't see enough of it to tell how it works.
I use it. I put the engine at TDC, put the disc on the rotor (nothing required for it to stick), and align the TDC slot in the disc with the timing mark on the rotor. Then I put a mark on the stator inline with the 30 degree mark on the disc. Then I remove the disc, put the primary cover on and record how much it is off, if any. If you don't have the timing device in the primary cover that mark on the stator can be your timing mark.

You can do the same thing with a degree disc, but you'll be done with this in less time than it will take to setup the degree disc.
 
it is cheap enough and sounds like a good idea. I held up my order until I got more info on this.
 
If it does not require a degree wheel and a piston stop to determine TDC, it is not any more accurate than the factory scale...which may or may not be accurate. Remember that the factory scale has THREE variables...

1. The precise positioning of the outer chain case cover- you can make it shift a couple of degrees as you install the chain case cover.

2. The marking of the alternator Rotor by Lucas (or whoever)

3. the positioning of the woodruff key in the crankshaft by Norton or whoever.

All three must be exact to produce exact timing. Only a piston stop and degree wheel can verify it. Anything else is just "approximating." OTOH, unless you REALLY CARE, a couple of degrees error on a street motor won't make enough difference to make any difference.

Air bubbles, dial indicators, etc are not accurate if you want precise timing. BUT, again, for a stock Norton, I can't imagine that it matters much. ;)
 
If it does not require a degree wheel and a piston stop to determine TDC, it is not any more accurate than the factory scale...which may or may not be accurate. Remember that the factory scale has THREE variables...

1. The precise positioning of the outer chain case cover- you can make it shift a couple of degrees as you install the chain case cover.

2. The marking of the alternator Rotor by Lucas (or whoever)

3. the positioning of the woodruff key in the crankshaft by Norton or whoever.

All three must be exact to produce exact timing. Only a piston stop and degree wheel can verify it. Anything else is just "approximating." OTOH, unless you REALLY CARE, a couple of degrees error on a street motor won't make enough difference to make any difference.

Air bubbles, dial indicators, etc are not accurate if you want precise timing. BUT, again, for a stock Norton, I can't imagine that it matters much. ;)
It does require you to carefully turn the engine to TDC. A piston stop being my preferred method. Once TDC is accurately established, the tool lets you accurately find 20, 30, and 40 degrees before TDC. A degree wheel is not required. The accuracy of the rotor mark makes no difference - wherever it is when the engine is at TDC is TDC.
 
Last edited:
I just use the graduations on the stator.

View attachment 82754
I'm not sure I understand your point.

The entire purpose of this plate is to CALIBRATE the graduations on the stator and primary cover scale.

The scale is well known to be inaccurate and in my personal case 2.5 degrees out.

You can certainly use the markings on the stator to time the bike provided you accept the possibility they are inaccurate.

I guess I'm a bit fussy when it comes to timing but it's based on experience of how well a bike can go when you get everything right.
 
Last edited:
I'm not sure I understand your point.

This plate calibrates the markings on the stator and primary cover scale.

The scale is well known to be inaccurate and in my personal case 2.5 degrees out.

It is surmising the rotor mark which is being worked off is accurate which it might or might not be.
The problem or not is the stock scale has no TDC to verify easily.
#
I elected to positive stop TDC on the short block, transfer that TDC position to the mounted stator then machine (rotary table) the needed ignition timing degree graduations into it.
(Trying multiple outer primary covers out of curiosity with the stock scale returned 1.5 degrees off as the maximum inaccuracy which was a surprise)

I can see the merit in that AN 'tool to at least have some easy idea of what is going on.
TDC positive stop verified and the rotor circumference divided by 360 would soon give a degree's in mm measurement also.
 
It is surmising the rotor mark which is being worked off is accurate which it might or might not be.
The problem or not is the stock scale has no TDC to verify easily.
#
I elected to positive stop TDC on the short block, transfer that TDC position to the mounted stator then machine (rotary table) the needed ignition timing degree graduations into it.
(Trying multiple outer primary covers out of curiosity with the stock scale returned 1.5 degrees off as the maximum inaccuracy which was a surprise)

I can see the merit in that AN 'tool to at least have some easy idea of what is going on.
TDC positive stop verified and the rotor circumference divided by 360 would soon give a degree's in mm measurement also.
Hi. It's a time since I went through the exercise but I do remember finding TDC with a positive stop and then orienting the disc.

If I read your post correctly you have essentially turned the rotor into the disc marking up the rotor using the dividing head. A good method.
 
Hi. It's a time since I went through the exercise but I do remember finding TDC with a positive stop and then orienting the disc.

If I read your post correctly you have essentially turned the rotor into the disc marking up the rotor using the dividing head. A good method.

Some things I like to know for sure and timing is one of them.

What I did is use a positive stop bar either side of TDC with the cylinder head off, the TDC line on the rotor transferred to the stator for two marks split on the rotary table to get a marked TDC. The timing graduations were then machined into the green potting of the charging stator body up to 32 degree's.

This was when I was moving the stator and rotor inboard around 12 mm to suit the duplex primary so was there anyway.
All it means to me is, set a timing mark with the light and it will be very close to confirmed actual.
 
Some things I like to know for sure and timing is one of them.

What I did is use a positive stop bar either side of TDC with the cylinder head off, the TDC line on the rotor transferred to the stator for two marks split on the rotary table to get a marked TDC. The timing graduations were then machined into the green potting of the charging stator body up to 32 degree's.

This was when I was moving the stator and rotor inboard around 12 mm to suit the duplex primary so was there anyway.
All it means to me is, set a timing mark with the light and it will be very close to confirmed actual.
Yep I agree a solid stop either side of tdc and split the difference with a dial guage is the only way to get a precise tdc in my opinion
There's too much rock at tdc to be precise
Whether that precision is needed on an old Norton motor is another matter
 
Status
Not open for further replies.
Back
Top