Point gap and timing?
- Thread starter Rope42
- Start date
Check around the engine bay maybe?
Hi Rope,
I don't have an 850, but my 72 124 Special has a black plate riveted in the bay with the tune up specs on it. You can see it in the upper right corner, half hidden by other stuff. It is even riveted in upside down so it reads properly as you lean in over the fender. How thoughtful!
Maybe the 850 has something similar. Of course, all these cars are so old there is no telling what that "may" have had when new that has wandered off over the years.
Hi Rope,
I don't have an 850, but my 72 124 Special has a black plate riveted in the bay with the tune up specs on it. You can see it in the upper right corner, half hidden by other stuff. It is even riveted in upside down so it reads properly as you lean in over the fender. How thoughtful!
Maybe the 850 has something similar. Of course, all these cars are so old there is no telling what that "may" have had when new that has wandered off over the years.
kmead
Old enough to know better
The point gap is .0165-.0189" or .42-.48mm
The timing should be 0° BTDC.
The timing is set by aligning the two marks, one on the timing chain cover and one on the centrifugal oil filter cover.
The easiest way to set the timing is with the engine off.
1. First turn the engine so that the mark on the chain cover is aligned to the mark on the filter housing (ensure that cylinder 1 is at TDC). Then remove the wire from the points post on the outside of the distributor that goes back to the coil.
2. Take a flashlight bulb and solder a wire to the ground side of the bulb and another onto the bottom contact of the bulb. Attach one wire to the points post on the side of the distributor and the other wire to the wire you took off the points post (which comes from the coil). Loosen the distributor hold down nut.
3. Turn the ignition to "ON". The flashlight bulb will either be on or off. Most likely off.
4. Turn the distributor body until the light bulb turns on.
5. Turn the distributor body just slightly clockwise until the bulb just turns off.
You should now have it basically perfectly timed. Remove the light bulb assembly and return the wire from the coil back onto the points stud and you are done.
You can check with a normal timing light as well but this is the way to get the timing either in the ball park or to get to final timing or spot on if you have done it this way in the past.
As a reference from some of the manuals:
2. "When adjusting the ignition timing refer to Chapter 4,
Section 7 but, instead of following the instructions in
paragraph 3, turn the engine until number 1 cylinder piston is
at the top of its compression stroke, and the TDC timing marks
on the centrifugal filter cover and timing chain cover are in
alignment." (FYI - Chapter 4/Section 7.3 states the 10 degree
BTDC figure that we're all familiar with for the early 850's).
3. "If a stroboscopic timing light is being used, the ignition
timing must be checked with the engine at normal operating
tempurature, and the advance reading of 0 degrees (TDC) should
be checked with the engine idling at 850 rpm. Using a dwell
meter, check that the dwell angle is between 57 degrees and 63
degrees with the engine turning at the same speed."
The timing should be 0° BTDC.
The timing is set by aligning the two marks, one on the timing chain cover and one on the centrifugal oil filter cover.
The easiest way to set the timing is with the engine off.
1. First turn the engine so that the mark on the chain cover is aligned to the mark on the filter housing (ensure that cylinder 1 is at TDC). Then remove the wire from the points post on the outside of the distributor that goes back to the coil.
2. Take a flashlight bulb and solder a wire to the ground side of the bulb and another onto the bottom contact of the bulb. Attach one wire to the points post on the side of the distributor and the other wire to the wire you took off the points post (which comes from the coil). Loosen the distributor hold down nut.
3. Turn the ignition to "ON". The flashlight bulb will either be on or off. Most likely off.
4. Turn the distributor body until the light bulb turns on.
5. Turn the distributor body just slightly clockwise until the bulb just turns off.
You should now have it basically perfectly timed. Remove the light bulb assembly and return the wire from the coil back onto the points stud and you are done.
You can check with a normal timing light as well but this is the way to get the timing either in the ball park or to get to final timing or spot on if you have done it this way in the past.
As a reference from some of the manuals:
2. "When adjusting the ignition timing refer to Chapter 4,
Section 7 but, instead of following the instructions in
paragraph 3, turn the engine until number 1 cylinder piston is
at the top of its compression stroke, and the TDC timing marks
on the centrifugal filter cover and timing chain cover are in
alignment." (FYI - Chapter 4/Section 7.3 states the 10 degree
BTDC figure that we're all familiar with for the early 850's).
3. "If a stroboscopic timing light is being used, the ignition
timing must be checked with the engine at normal operating
tempurature, and the advance reading of 0 degrees (TDC) should
be checked with the engine idling at 850 rpm. Using a dwell
meter, check that the dwell angle is between 57 degrees and 63
degrees with the engine turning at the same speed."
Last edited:
Timing is 0º TDC at 850 rpm, dwell is 57º-63º. Point gap is .016". Earlier cars had more advanced timing, the later models with the 903 engine had slightly different distributor timing curves.
kmead
Old enough to know better
That procedure is for when you have no idea what the timing is. Merkel Weiss taught me that one and gave me a little bulb and wire assembly twenty five years ago and I still have it and occasionally use it . It works well on my 1438 twin cam as well given what a pain its distributor is to do work on.
. It works well on my 1438 twin cam as well given what a pain its distributor is to do work on.
Jeff Stich
True Classic
Engine Specs tag
There should be an Engine Tuneup Specifications ID plate/tag like this on the firewall just above the radiator:
There should be an Engine Tuneup Specifications ID plate/tag like this on the firewall just above the radiator: