74 850 timing issue

Hello, I have a 74 850 I am having ignition timing issues with. I went through the static timing process in the manual, removed the points cam, cleaned an lubricated the adv mech, replaced the springs, reassembled the cam with the notch down just like I removed it, put the points plate back in, adjusted the points to .015, locked the points cam in the fully advanced position with a washer and attempted to locate the point opening position. I have done this many times over the past 30 years with no issue. However, this time the point opening position is about 90 degrees from where it was before and is beyond the adjustment range of the points plate and the individual point set adjustment cam. As a precaution I always set the crank to 28 degrees before starting just to make sure I don't mess anything up.
The manual mentions that you have to adjust the cam position if you have removed it, but mine only goes on in one of two positions 180 degrees apart which is why I always remove it with the cam notch down so I know how to put it back.
I have obviously missed something but after 5 days of struggling with this issue I am at a loss as to what it might be.
I thought that maybe the back advance plate came loose but I cannot move it at all.
Any insight would be greatly appreciated........Thanks.......Jerry

850bruno said:

However, this time the point opening position is about 90 degrees from where it was before and is beyond the adjustment range of the points plate and the individual point set adjustment cam.

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Sounds like the timing could have been set up using the wrong alternator rotor timing mark as that would throw the points cam out by 90 degrees

I thought there was only one alternator timing mark......I will check.

You're not far from me. Remember the spark occurs when the points open. I always seem to forget that part. But I've got the Pazon now, so what do I know?

Dave
69S

Pull the electrode out of a spark plug and use a soap bubble to find TDC, and set the timing up with a degree disc to the manufacturer's spec.

There are 2 timing marks on the rotar on the 74 850, just look in the spark plug hole to see if the pistons are TDC if not turn the motor to the other mark.

Ashley

Well now, I marked the timing mark with a black magic marker and low and behold there are two timing marks. My assumption was that the rotor was driven off the crank and since the pistons are parallel there would be only one timing mark indicating TDC. I was wrong........Thanks......Jerry

850bruno said:

Well now, I marked the timing mark with a black magic marker and low and behold there are two timing marks. My assumption was that the rotor was driven off the crank and since the pistons are parallel there would be only one timing mark indicating TDC. I was wrong........Thanks......Jerry

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The issue is the original rotor is a Lucas part, not a Norton part, and made for multiple applications. Most replacements are Emgo or Wassell, but patterned after the Lucas.

One trick is to assemble the rotor on the crank, rotate the crank to TDC, paint the upper timing mark with white paint, then paint the flats on each side of the mark with black paint. You'll know which mark is correct (the white one), and the mark will really stand out when hit with a timing light.

Thanks for your help. I knew it had to be something simple and stupid.....I was right about that but I would have never guessed there were two timing marks.......Thanks again......Jerry