Distributor Recurve - MSD Timing

[North Coast Cab]

If I run the MSD 8680 Adjustable Timing Computer would I still need to have my distributor recurved? The 8680 provides 15d of adjustability. I'm running a single plug 10:1 compression 3.0 motor.

Thanks, John

[RoninLB]

Adjustable Timing Control,
PN 8680
The MSD Adjustable Timing Control puts you in control of your ignition timing - from the driver's seat! A dash mounted control knob allows you to adjust the ignition timing to compensate for changes in altitude, low octane gas, or heavy loads. For cars driven every day but raced occasionally on the weekends, this control is perfect. Increased fuel mileage and performance are just some of the benefits as the ignition timing can be advanced or retarded to prevent engine detonation.
The control knob mounts to the dash board for easy and accurate timing adjustments up to 15°. The Control can be used on 4, 6 and 8-cylinder engines and must be used with an MSD Ignition Control.




Timing Computer-Fixed Curve,
PN 8980
The PN 8980 Timing Computer has a pre-programmed timing curve that eliminates the need for a mechanical advance.
When you start the car, the Timing Computer retards the timing 20° from the set mechanical timing. This provides easy starting and smooth idle. The timing begins to advance when the engine speed reaches 1,000 rpm and continues until 3,000 rpm when the total timing is reached.
The Timing Computer also has a separate high speed retard circuit. This allows you to activate a retard amount via a switch to retard the timing during times of nitrous or high rpm. The retard amount is adjustable with plug-in modules and 2°, 3° and 4° modules are supplied. Page 90 has a full selection of modules and selectors.

[ValveFloat]

The way I read the description of the 8680, it will just offset your whole curve, not change the shape of it. Essentially doing the same thing as adjusting your timing by turning the distributor.

Recurving can give you a different shape curve.

I am using the 8980 on my L. It was a lot less expensive than getting my distributor rebuilt/recurved. With the "high speed retard" and some trickery I am able to change the shape of the advance curve some.

The 8980 required an MSD (or Crane) ignition box to function, although I would guess they could be used with the Bosch CDI. I assume the 8680 has the same requirement.

[mack6820]

question though. I advanced my 3.0 timing to 23 degrees but then I also had to adjust my mixture and idle. Is that normal?

[North Coast Cab]

Race car, no factory wiring. here's what I have.
MSD 6AL
MSD Blaster Coil
MSD Timing CPU 8680

Now I'm trying to figure out the wiring.

[RoninLB]

Originally posted by North Coast Cab

Now I'm trying to figure out the wiring.

if mine I'd wire it with waterproof connectors and everything soldered so the 8680 can be unplugged and the engine run without it on a proper curve.


how much did it cost ?

[North Coast Cab]

About $425 not including the distributor.

It's all mounted and ready to go in, but I'm still a little lost on the wiring. Is the distributor supposed to have one or two wires coming out of it?

[RoninLB]

Originally posted by North Coast Cab


Is the distributor supposed to have one or two wires coming out of it?

MSD wiring advice (connectors)

[mack6820]

Now that I adjusted my timing. The car runs great but when I stop at a 7-11 or something and get back in, the car idles at 2000 rpm. The engine never cooled off so it shouldnt be idling that high, Once I get on the road, it calms down.

[rfn026]

Who would you folks recommend to recurve a distributor for my 911?

Richard

[Gunter]

Apex will do it; right down the road from you.