there is no hard fast rule here. but typically with the cap off and number one cylinder at TDC on compression stroke. the rotor will point at number one cylinder on the engine.
if it is a hei ignition there is a place on the distributor cap that says tach.
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under the rotor on the inside of the distributor cap
at 11 Oclock
There is a notch in the distributor housing. It can only go one way.
Rotor Under Cap Spins: Clockwise
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I DON'T KNOW!
It is on the back of the intake manifold just in front of the distributor. If it is a HEI vehicle it will be in the center of the distributor cap. (distributor cap will look larger than normal)
When working on a car, and troubleshooting problems, knowing the firing order can come in handy. The firing order of the distributor cap of a Chevy 350 is 1-8-4-3-6-5-7-2.
The cap doesn't spin at all. The rotor turns clockwise.
1-8-4-3-6-5-7-2 clockwise on cap.