Pertronix Billet with mechanical locked out?

[xLURKxDOGx]

Anybody running this?? I realized i had locked it out (with the limiters, wrong color i suppose) in favor of the vacuum by accident and ive done a bunch of reading about it and cant seem to find a clear advantage to it. I was wondering if i should set the minimum which i believe is 16* mechanical , and if so what is the advantage???


Thanks,

Jake

 

[RustyRatRod]

Street car? If so, there's a big disadvantage regarding mileage running timing locked out.

 

[TrailBeast]

Street car? If so, there's a big disadvantage regarding mileage running timing locked out.

X2, that and performance too. (for normal driving)
Locked out timing is mostly for flat out race cars that run wide open 99% of the time.

 

[AJ/FormS]

If you run the can on a locked dizzy, it can bring 18 to 20 degrees in on top of the locked amount. So the engine could see something like 54* at about the time that the manifold vacuum peaks or even sooner; and at rpms below that it could be way over advanced; so that would be bad. But if you put the mechanical back in and run idle-timing at something like 16* then,with the can, it might only be adding up to 34, at that same time, and it would be ever-changing depending on what the throttle is doing . If you manipulate those two, you can build a sweet responding lowend into your combo that might otherwise be lazy or have a hard-to-find hesitation. And as mentioned, if you get it right, you could get the cruise timing at something like 48 plus degrees, or what ever the combo likes, and gets the best mileage, which you cannot do with a locked timing.You might be surprised how much timing the engine wants when cruising. Mine likes over 48*. Some situations, she likes over 54*!
Plus the engine will run cooler and smoother as she gets the timing shes been craving.
And the best part is when you hit the skinny pedal, all timing reverts to mechanical.So whatever you set the max to, that will be what you get.
Since a street car spends a huge amount of time under the torque peak, it pays good dividends to get this worked out, even if it means a small sacrifice in power timing (at the lower rpms,) and even idle timing.
For instance; if your combo likes 18* at idle, but does not like any more for another 600 rpm, what can you do? Easy. Dial it back 4 to 6 degrees and bring it in with the can instead. But what if at 2800 and light cruise the engine complains about the 34 mechanical plus 20 vacuum. Easy. Put a staged second spring in there a lot stiffer than the first. This will put a kink in the mechanical curve somewhere; it will be fast to a point and then crawl up to the max power-timing. If you get it right the engine will always be running near optimum timing. Or you could just get a computer......and really make it tight.

 

[TrailBeast]

If you run the can on a locked dizzy, it can bring 18 to 20 degrees in on top of the locked amount. So the engine could see something like 54* at about the time that the manifold vacuum peaks or even sooner; and at rpms below that it could be way over advanced; so that would be bad. But if you put the mechanical back in and run idle-timing at something like 16* then,with the can, it might only be adding up to 34, at that same time, and it would be ever-changing depending on what the throttle is doing . If you manipulate those two, you can build a sweet responding lowend into your combo that might otherwise be lazy or have a hard-to-find hesitation. And as mentioned, if you get it right, you could get the cruise timing at something like 48 plus degrees, or what ever the combo likes, and gets the best mileage, which you cannot do with a locked timing.You might be surprised how much timing the engine wants when cruising. Mine likes over 48*. Some situations, she likes over 54*!
Plus the engine will run cooler and smoother as she gets the timing shes been craving.
And the best part is when you hit the skinny pedal, all timing reverts to mechanical.So whatever you set the max to, that will be what you get.
Since a street car spends a huge amount of time under the torque peak, it pays good dividends to get this worked out, even if it means a small sacrifice in power timing (at the lower rpms,) and even idle timing.
For instance; if your combo likes 18* at idle, but does not like any more for another 600 rpm, what can you do? Easy. Dial it back 4 to 6 degrees and bring it in with the can instead. But what if at 2800 and light cruise the engine complains about the 34 mechanical plus 20 vacuum. Easy. Put a staged second spring in there a lot stiffer than the first. This will put a kink in the mechanical curve somewhere; it will be fast to a point and then crawl up to the max power-timing. If you get it right the engine will always be running near optimum timing. Or you could just get a computer......and really make it tight.

I have 52 total all in at 5,500 ft elevation and when I got that all set I could tell that it took less throttle to move the car.
Freeway milage got a bit better also.
If I drop down a couple of thousand feet in elevation I have to drop the timing back a couple of degrees to clear pinging at WOT.
As a matter of fact I think you and I were discussing that back then.

 

[AJ/FormS]

I think we did kick the can around.
I have a dash-mounted timing retard device which allows me to change the timing while driving, up to 15 degrees. So it allows me to get the timing really close.I highly recommend it.

 

[KitCarlson]

So you are trying to push past primative timing controls. You might be ready for 3D RPM, MAP tables, timing temperature compensation and knock control. While you are at, EFI, since timing and mixture are dependent variables. That might come with COP ignition.

 

[xLURKxDOGx]

Street car? If so, there's a big disadvantage regarding mileage running timing locked out.

Street car.

X2, that and performance too. (for normal driving)
Locked out timing is mostly for flat out race cars that run wide open 99% of the time.

Thats what i read as well, and that makes a lot of sense now that i think about it.

If you run the can on a locked dizzy, it can bring 18 to 20 degrees in on top of the locked amount. So the engine could see something like 54* at about the time that the manifold vacuum peaks or even sooner; and at rpms below that it could be way over advanced; so that would be bad. But if you put the mechanical back in and run idle-timing at something like 16* then,with the can, it might only be adding up to 34, at that same time, and it would be ever-changing depending on what the throttle is doing . If you manipulate those two, you can build a sweet responding lowend into your combo that might otherwise be lazy or have a hard-to-find hesitation. And as mentioned, if you get it right, you could get the cruise timing at something like 48 plus degrees, or what ever the combo likes, and gets the best mileage, which you cannot do with a locked timing.You might be surprised how much timing the engine wants when cruising. Mine likes over 48*. Some situations, she likes over 54*!
Plus the engine will run cooler and smoother as she gets the timing shes been craving.
And the best part is when you hit the skinny pedal, all timing reverts to mechanical.So whatever you set the max to, that will be what you get.
Since a street car spends a huge amount of time under the torque peak, it pays good dividends to get this worked out, even if it means a small sacrifice in power timing (at the lower rpms,) and even idle timing.
For instance; if your combo likes 18* at idle, but does not like any more for another 600 rpm, what can you do? Easy. Dial it back 4 to 6 degrees and bring it in with the can instead. But what if at 2800 and light cruise the engine complains about the 34 mechanical plus 20 vacuum. Easy. Put a staged second spring in there a lot stiffer than the first. This will put a kink in the mechanical curve somewhere; it will be fast to a point and then crawl up to the max power-timing. If you get it right the engine will always be running near optimum timing. Or you could just get a computer......and really make it tight.

I think we did kick the can around.
I have a dash-mounted timing retard device which allows me to change the timing while driving, up to 15 degrees. So it allows me to get the timing really close.I highly recommend it.

WHere did you get it and who makes it???

Jake

 

[AJ/FormS]

Mine is a Jacob's. It is a stand-alone unit for non-CDI ignitions. It's been on the car since near the beginning, something like 12 years now. MSD makes all kinds of stuff.