Vacuum advance

[Russell Fulks]

Hello All,
Could anyone tell me if the distributor vacuum port is timed (no vacuum at idle) or full (vacuum present at idle).

The vehicle is a '77 L82 4-speed.

Thanks,
Russ

[Mark Ring]

Re: Vacuum advance

Russel,
Since you were left hanging I figured it safe to guess... I would go with a "ported" vacuum tap that has no vacuum at idle rather than a manifold full time vacuum port. I don't remember seeing it done any other way by the factory since emissions came into effect. There may be some intermediate stops between the tap and the can but I am unfamiliar with that particular setup. You could tune it differently and go with the full manifold vacuum but that is more work, non-stock and not NCRS spec. Maybe this helps in some way.

-Mark.

[Mark Ring]

Re: Vacuum advance

Russel,
Since you were left hanging I figured it safe to guess... I would go with a "ported" vacuum tap that has no vacuum at idle rather than a manifold full time vacuum port. I don't remember seeing it done any other way by the factory since emissions came into effect. There may be some intermediate stops between the tap and the can but I am unfamiliar with that particular setup. You could tune it differently and go with the full manifold vacuum but that is more work, non-stock and not NCRS spec. Maybe this helps in some way.

-Mark.

[russell fulks]

Re: Vacuum advance

Thanks,

I've heard both but no one has been certain yet. It "seems" to run better with full vacuum, but that may just be because my mechanic originally tuned it with no vacuuum advance.

I appreciate the response.

Russ

[russell fulks]

Re: Vacuum advance

Thanks,

I've heard both but no one has been certain yet. It "seems" to run better with full vacuum, but that may just be because my mechanic originally tuned it with no vacuuum advance.

I appreciate the response.

Russ