What is the correct way to hook up the MSD digital 7 so it handles all the timing and the FAST unit handles just the fuel?
I can see your point, but the D7 can only retard from what is being fed into it, which is where I think the FAST system can help out.Sparky said:Juiced 10.5,
All the wiring is left as is, just change the base spark table as I mentioned above and your off and running.
In my opinion, I feel it’s redundant to have the FAST system or any other aftermarket EFI system, tell the Ignition, how to control the coil, especially when the Digital 7 has more advanced features and a faster processor over the EFI systems.
It only makes good sense to utilize the MSD Digital 7 features with an EFI system.
With the two of these components working together, it helps alleviate the EFI system from doing all the work. This in itself makes the two systems more efficient, tuning changes are more effective, making the whole program much more consistent.
I have had good success with using the Points wire from the EFI System fed to the Points lead on the Digital 7.
I’m sure you could add a second independent Crank Trigger for the Digital 7, but I don’t know how much value added there would be in doing so.
I see your point, it just seems like a waste to me to buy a FAST system and not use it to it's potential. *shrug*Sparky said:Most of the Aftermarket ECU's use a crank sensor and if it's sequential, we use a cam sync of sort.
Granted, Accel offers a Dual Sync Distributor, I’m not saying that you can’t hook up an EFI system through a Distributor. But, I don’t think you will do it with a Distributor that isn’t locked out. This would adversely affect the Crank Angle Reference with in the EFI ECU.
If Cam twist and all of the other variables that you mentioned above are a factor, wouldn't you install a crank sensor to begin with?
The signal that the EFI ECU sends to the Digital 7 through the points wire is triggered from the Crank Sensor. Therefore, you would not be getting a misleading trigger signal.
I understand that there are different variables for different situations and I am not trying to argue your point. But, Steve Petty & Tim Lynch went 6.97 in qualifying, 208.9 mph in eliminations and won Orlando. They also ran some very impressive numbers at Huntsville the weekend before, 4.50 flat in the 1/8th. I set this car up like all the others I have wired using a Digital 7 and EFI. This has seemed to work quite effectively.
There are ways with the Digital 7 to advance timing in, as well as retard timing. It’s all in the way you manipulate the timing. Don Bailey and I spoke at Orlando about adding a second Crank Trigger to a car, but again it was more for timing manipulation and not for accuracy concerns.
Yeah that was my thoughts on it, again, I had a brain fart about the crank sensor and FAST system.If Cam twist and all of the other variables that you mentioned above are a factor, wouldn't you install a crank sensor to begin with?
Any idea what the processor speeds are?Jim Monson said:The MSD's processor is faster than the FAST processor. LOL, say that 10 times fast! The FAST ecu seems to drop things when you ask too much from it. It's kind of like when your computer is doing to many calculations and it locks up. Since spark timing is such a critical part of power and durability, I let the MSD control the spark. I also use the MSD's boost retard function. The injectors are hard wired into the FAST unit. The ecu does not have to think that much about fuel delivery. Sparky, jump in here if I'm off base.