Distributor Cap 101

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Jim McLain

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Here's a grade school question for you. How do you know which point on the distributor cap corresponds to #1? Is the position of #1 based on the location of the vacuum advance or the tab located near it? And do the tabs advance CW or CCW?

Thanks, Jim
 
Jim McLain said:
Here's a grade school question for you. How do you know which point on the distributor cap corresponds to #1? Is the position of #1 based on the location of the vacuum advance or the tab located near it? And do the tabs advance CW or CCW?

Thanks, Jim
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You would have to bump the engine to TDC on the compression stroke of the #1 cylinder and see which post on the cap the rotor points to. It's not necessarily related to anything else external.
 
No neither. You did not say if everything is already in place on the engine. If so, follow the #1 plug wire to the cap, and that should be #1. If not, you have to find TDC and rotate the Distributor drive gear in so it lines up with the front left intake manifold bolt. That aligns the rotor straight ahead and at #1. There are books that can show you the process.
 
Roger. Guess I should have mentioned this is a slant 6 and everything is in place. However, I recently replaced my plugs and wires and now the car won't start. Gap is correct on all and I replaced the wires one at a time on the cap, so it should start, but it won't. I'm just trying to eliminate the possibility that I had a brain fart during the process.
 
Ok, so #1 on a slant is the plug at the front of the engine, and when your standing in front the wire should go on the distributor first on the left. Not the one straight ahead, but first to left. Google slant six firing order
 
The distributor cap is made so it only fits on the distributor body in one position.
To determine which post is number one, you would put the #1 cylinder engine at TDC on the compression stroke, and install the distributor so the rotor aligns with the post on the cap.
On a small block, the number one post is in the front of the cap, almost on the crank centerline.
Small block rotors rotate clockwise, big block rotors rotate counterclockwise.


Ah, while I was writing this, it turns out to be a leaning tower of power. I think the questions have been answered already.
 
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