On MSD's new programmable box, a launch retard (up to 15 degrees) can be dialed in when the launch rev limiter is engaged. What is the purpose of this?

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig) with 50-hp nitrous: 12.043 @ 112.86 mph.
ATI D1SC (10-psig): 12.056 @ 116.62 mph.
All stats are altitude corrected for 3,100 feet using NHRA's Altitude Correction Table.

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

I replied on the camaroz28 web site already

 

Stephen, thanks for responding on the Z28 board. Here's verbage directly from MSD's instruction manual:

Launch Retard
This feature lets you program a retard amount that will be activated when 12 volts are applied to the Dark Blue wire (also used for the Launch rpm limit). It is programmable from 0 - 15 degrees in 0.5 degree increments and can be set to ramp back to the Run Timing within 0 - 2.5 seconds after 12 volts are removed from the activation wire (Dark Blue).

It doesn't explain why you want to do this..... Now I'm wondering....

Willie

 

Like I mentioned on the Z28 board. You wouldn't want to use it on a distributor that has an advance curve. It just sounds like a way to do a brief advance curve during launch. 0 - 2.5 seconds after launching you're back at the locked out full advance.

I don't know why you would use it. Possibly to keep the power curve down while using power adders during launch? Since you should be at full advance by 3000 rpm, you should be there before 2.5 seconds into the launch anyway.

If I load up my converter, I'll launch at around 2500 rpm. It only takes a fraction of a second to be above 3000 rpm.

E-mail MSD and ask them why you would use it. There must have been a demand for something like that for them to produce it.

When I bought my ignition I was going to use the MSD Digital 6 box. Some of the options I wouldn't need. I bought a Holley Annihilator instead because it had better options I could use.

 

I'm going out on a limb on this but like Stephen said it would keep the power curve down. So if it keep the power curve down for up to 2.5 sec this would allow for a maybe a slightly better 60' time since less spinning? Then back to the regular timing and power for the rest of the way down the track. I think this would help since alot of times I hear people saying "I feather the throttle so I don't spin too much of the line". With this you retard the timing so many degrees to lower the power curve and get a good 60' time with full throttle then back to normal timing curve and never have to feather the throttle.
Like I said I don't know for sure but this is what I get out of it.

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89 IROC 350 Auto
MSD 6AL
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
And Free mods.
(stock intake, runners and suspension)

13.879 @ 98.90 mph (with 2.77 gears!)


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