Vortec Head Timing With Progression Ignition

[Old60Driver]

Howdy!

Anyone running a Progressive Ignition system with Vortec heads? I'm trying to fine tune the timing curve as I think I'm leaving some performance on the table.

For those that don't have this kind of ignition, I'd still like your opinion. I've read that Vortec heads don't like or need anything over about 32°. Is that WITH vacuum advance? Or BEFORE vacuum advance? I can also set HOW MUCH vacuum advance I want, and where I want it to start and stop. If you haven't figured it out already, I'm a noob when it comes to timing. LOL

Thanks in advance!!

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[legopnuematic]

32° is going to be your total advance, that is your base timing + mechanical advance.

So if you are base timed at 12°, you want 20° of mechanical advance to get to 32°

The vacuum advance should be disconnected (carb port plugged) when setting both initial and checking mechanical advance.

Vacuum advance adds timing in high vacuum situations like cruising steady speed on the interstate. Punch the throttle, vacuum drops and the vacuum advance pulls timing back be back on the mechanical advance. Wide open throttle for example will be all mechanical advance as there is (or shouldn’t) no vacuum at WOT.

 

[SquareRoot]

Is this a stand alone system or part of an EFI? I have the same capability with my pf-4. It's nice to tap your phone for adjustments rather than turn a wrench. I also have vortecs (@Rusty Nail favorite). Set base at 12 and total at 32 like said above. Getting the curve right is the tricky part that determines drivability.

 

[Bextreme04]

Howdy!

Anyone running a Progressive Ignition system with Vortec heads? I'm trying to fine tune the timing curve as I think I'm leaving some performance on the table.

For those that don't have this kind of ignition, I'd still like your opinion. I've read that Vortec heads don't like or need anything over about 32°. Is that WITH vacuum advance? Or BEFORE vacuum advance? I can also set HOW MUCH vacuum advance I want, and where I want it to start and stop. If you haven't figured it out already, I'm a noob when it comes to timing. LOL

Thanks in advance!!

You must be registered for see images attach

maybe start with a base timing map from an L31 truck/suv/express van from 96-2005?