Small cap HEI, #1 terminal?

[Galane]

Where in relation to the ignition module plugs is #1 terminal on the cap?

There are no markings on my shiny new red cap and billet distributor. All the diagrams I find just show a round circle with nothing to indicate where the module is, just that #1 is roughly aimed towards the left front of the engine.

 

[SkinnyG]

I have a small cap HEI in my Chevy Sprint (not a transverse 3 any more), and there is a "#1" cast between two posts ~inside~ the distributor. I used whichever post seemed the closest. Functionally it doesn't really matter which post you use, as long as the correct plug is firing.

 

[Galane]

My old one has a top plate of sheet aluminum attached to a cast body. No numbers or any markings on the top side.

Where in relation to the module is the terminal you're using for #1?

 

[SkinnyG]

This is the same terminal that was used when I pulled the motor. I did not find a consistent "proper way" to point the rotor, so I just used what it was, since it was so hard to get my hands in there (distributor is about where the dashboard is). It's a bugger to work in there. It will still work.

I'd probably point the rotor to cylinder #1 (traditional) if I were you.

Probably not the best source for an image here.

You must be registered for see images attach

 

[SkinnyG]

You know, it would probably be better if someone else posted here. I don't think I'm a lot of help to you.

 

[MadOgre]

The #1 plug will be determined by where the distributor rotor is pointing in relation to the crankshaft/ camshaft. So if you set the distributor forward or backward one or more teeth on the camshaft by adjusting the slotted oil pump then you would have to move the cap accordingly to capture the rotor on the correct plug wire on the cap.

SO the distributor shaft in relation to the camshaft will determine where that #1 plug ends up sitting and the cap must follow.

Generally the #1 plug faces the #1 cylinder. But if you desire it to be in a different location for what ever reason simply adjust the distributor shaft to camshaft position. This requires you to remove the distributor and with a long flat screw driver adjust the slot on the oil pump forward or backward to achieve the location you desire.

This may involve many trial and error attempts to get it in the right location. How ever it is this that determines your #1 plug location.

 

[rich weyand]

I'll add a note here.

It does not matter how the distributor body is oriented. The only thing that matters is that whatever high-voltage terminal post the rotor is pointing at when the #1 cylinder is at ignition-top-dead-center (as opposed to exhaust-top-dead-center) is connected to the #1 cylinder and the rest proceed clockwise in order.

That said, the distributor body is normally oriented so that the electrical connections come straight out to the left (driver's side, about 3 o'clock when viewed looking down at it while standing in front of the truck) and the vacuum can comes out forward and to the passenger's side (about 7 o'clock when viewed looking down at it while standing in front of the truck).

The rotor can also be put in any which way, as long as the high-voltage terminal the rotor is pointing at on #1 ignition TDC is connected to the #1 cylinder.

That said, the rotor is normally installed so that the rotor is pointing at about 5 o'clock when viewed looking down at it while standing in front of the truck when the #1 cylinder is at ignition TDC.

The #1 cylinder rod throw for every GM V8 is aligned with the keyway in the crankshaft to which the crankshaft pulley mounts. This is visible in the front of the engine. As the GM V8s are 90* V8s, the rod throw is at 45* clockwise from straight up when the #1 cylinder is at either TDC. So the #1 cylinder is at TDC when the keyway on the crankshaft pulley is at 45* clockwise from straight up, or 1:30 o'clock when looking at the front of the engine.

Note I have distinguished between ignition TDC and exhaust TDC. That is because the crankshaft rotates twice for every rotation of the distributor, and there are two TDCs on each cylinder per distributor rotation. On ignition TDC for each cylinder, the valves are closed on that cylinder; on exhaust TDC for each cylinder, both valves are partially open. You can test which TDC you are at by blowing air into the spark plug hole with an air compressor air chuck. If you can blow air through the cylinder, this is the exhaust TDC. If all the air comes back at you and tries to push the air chuck out of the spark plug hole, this is the ignition TDC.