High Point on Cam

[pjdeb]

My up close eye sight is poor to say the least. Is the high point on the distributor cam on the leading edge of the slot or the middle of the slot?

 

[Will N]

I think the answer to that depends on which cam you have. I believe the original Model A profile cam gradually opens the points and that the highest point on the lobe is in the center of the lobe and/or slot for the rotor. The Model B profile cam (which is the one all the vendors sell now) snaps open the points quickly and the high point begins at the leading edge of the lobe/slot and maintains that same lift for nearly the width of the rotor slot.

 

[The Master Cylinder]

So it is safe to say when adjusting your point gap have the rubbing block in the middle of the slot.

 

[Purdy Swoft]

There is a tool that slips over the distributor cam that mimics high cam where the points should be set . This tool saves a lot of time and effort . I use this tool with good results .

 

[pjdeb]

What is that tool and where did you get it?
Thanks

 

[30 Closed Cab PU]

Points gapping tool, Brattons


https://www.brattons.com/quick-set-point-setting-tool.html

 

[captndan]

Better yet is borrow a dial indicator then mark the cam with something like finger polish.

 

[Standing Elk]

Since it is really easy, I just pull the distributor out of the car clamp it in some soft jaws in my vise and set the point gap using a dial indicator. Makes doing the procedure really handy in pretty much fool proof.

 

[100IH]

The camshaft for the valves on a flat head is momentary because it is pointed but the bottom of the lifter is wide enough to keep the valve open longer. The distributor cam is the opposite scenario. The dist. cam has a wide face and a narrow rubbing block. For the purposes of ignition timing, the crank turns a substantial distance with the points open and another distance with the points closed. When does the spark occur? It is when the points just open. That is best found with a test light but the click of the spark is the same thing. As long as the crank is turned in the same direction as the engine runs and the slack in the system is removed by gently turning the dist. shaft opposite of its normal direction, then TDC is when the first lights and the current no longer flows to the grounded point. You will be able to see the light go on with a click of the spark. And now I see the problem is me. Your trying to gap the points and the special won't help much. So, once the points open and the click is heard, continue turning the crank about 18 deg. and that will be exactly between open and closed, the exact spot with lots of leeway.