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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?
 

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Assuming you have the wring correct. You would need to have the White Wire from the FAST system (Labeled Points), hooked to the Points Wire on the MSD 7531.
Once this is accomplished, you need to go into the Base Spark Table in the FAST System and set the whole table to your total timing setting. For example, if you want the engine to run at 34 degrees total timing, then this is the value you would put into the table. Now you can make all your timing settings within the Digital 7.

I hope this helps
Sparky
 

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Discussion Starter #3
Thanks for the reply Sparky. So what you are saying is that everything is still wired the same(cam sensor/crank trigger) as if you were using the FAST for the timing? Thanks again.
 

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Just curious why you don't want to use timing control in the FAST system? To me, it could be advantagous to do so.

Also for locked out timing, myself, I would not have any of the FAST system connected to outputs to the ignition system, but instead use a magnetic pick up (like a crank trigger) directly to the Digital 7.
I'm sure you will have to retain the cam and crank postin sensors to run the furl side though.
 

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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.

Six Shooter,
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.

Sparky
 

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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.

Six Shooter,
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.

Sparky
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.

I realize that most people will be running locked out timing, but not everyone. I know myself I probably won't be, and if I can afford it, I may take a serious look at the Fast system, for now I will be running a modified stock ECM.

Anyway, to my point.

Using the timing control in the FAST ECM, it can advance and retard the ignition timing, making it a bit more streetable or easier to stage drive to and through the staging lanes, etc. The D7 can then take away any timing that needs to be through it's very cabable programming.

Now, my reasoning for saying to nix the points input and run direct crank trigger again, would be becasue of teh locked out timing, but it's also more accurate to pull that signal from the crank, cam shaft twist (bigger problem on SBC than SB/BBF and Buick engines), timing set stretch, gear lash, etc, all effect timing and accuracy in comparison to the piston position in the cylinder, so if accurate timing is desired for total locked timing, the crank trigger would be ideal. Cam twist is non existant, no play in the gears or timing set, and will stay set to where it was set in relation to piston position.

But I think this all depends on the actual build and what the rules allow.
 

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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.

Sparky
 

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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.

Sparky
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*

Yes I know you can "advance" the timing with the MSD, that "0" can be where ever you want it. ;)

For some reason I wasn't thinking about the FAST system having a crank trigger, I was thinking it was a trigger from a dizzy to the 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?
Yeah that was my thoughts on it, again, I had a brain fart about the crank sensor and FAST system.
 

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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.
 

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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.
Any idea what the processor speeds are?
 
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