Hei gm ignition
Fleet Mechanic
Joined: Nov 2002
Posts: 1,643
Likes: 69
The HEI unit will not adjust your timing whatsoever. It is merely the triggering unit and power supply for the primary side of your coil. The engine timing will still be controlled by your distributor and the spark will still come from your coil.
On many years engines the factory ignition initial timing spec is 6 degrees, but some folks have tried bumping it up to 10 or so. That only takes a twist of the distributor.
On many years engines the factory ignition initial timing spec is 6 degrees, but some folks have tried bumping it up to 10 or so. That only takes a twist of the distributor.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
After I gave DUI (performancedistributors.com) my engine/vehicle specs and they created a custom tuned HEI for my engine, they told me that they designed it to be set at 12° base timing.
However, that's how they designed it, which means the rest of the timing (mechanical advance, vacuum advance), took that into consideration.
However, that's how they designed it, which means the rest of the timing (mechanical advance, vacuum advance), took that into consideration.
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