Ignition setup - Digital-7 part #7535

[whytry]

I currently have the MSD6AL with Boost retard and am not as happy as I would like to be, I have done some research on this site and I have read about the MSD Digital-7 but I am not sure of which one to look at. Would it be Digital-7 part #7535? I am noticing a little of a surge while cruising and also a little "popping" out the tailpipes while at cruise speeds, almost like its missing or something. My carb is a CSU prepped 850, and the initial AF at idle is about 18:1 and we can't get it much lower, 4 corner idle screws are turned out about 3.5 turns and I have talked to CSU and are thinking I need to lock out the dist @ 40 and then use the BTM to retard the timing. From what others have said here that's not going to be the best option for street driving, track sure, but not cruising around town. At WOT it is closer to 12.4:1. I had the distributor worked on before I called CSU and max is 28 now, but I can change it and set it @ 40, if that's best, dist is Mallory 9000. If I am off, I am very open to ideas..



Thanks

[Supervette]

He said the same thing to me as well. But I hear the digital 7s arent meant for the street? Here is what one of the local guys said to use http://www.jegs.com/webapp/wcs/store...0002_146904_-1

[whytry]

Really, that's interesting. Do you know what the difference it between the 2? They look to both be able to create your own timing curve based on boost, and give you more timing at cruise too..

[Turbo Hen]

been using my Digital 7 on the street for 2 season now....

the MSD "ANALOG" boxes such as the "7AL" are not to be used on the street, the digital ones are fine.

-Carm

[Supervette]

honestly i dont know the diff but I know theys sound like they do exactly the same thing but one is cheaper.

[Turbo Hen]

the MSD "AL" series ignitons, IMO, belong in a museum.

BTW, the 7531 if in your budget, has some more features which can come in usefull.

-Carm

[Supervette]

What are those features? That cheaper box i referenced to earlier I think can get paired with a digital 6 since this is already what I have. Piggybacked is the terminology he used.

[Turbo Hen]

Slew rate control, 20 sec datalog of timing vs. boost & rpm, launch rev control, etc...

-Carm

[whytry]

OK so the 7531 is that much better for boosted applications? I am running Procharged with CSU, and would like to run pump gas too. So basically I do everything EFI does in terms of making my own timing curves, and making adjustments for cruise and WOT as well?

[Turbo Hen]

yes......the 7531 is DEFINETLY the better box if you can spare the extra $$$

-Carm

[Adam's 55 Chevy]

Can this box be run on the street for long periods of time or is it a race box only. I have an unused digital 6. Would I be better off using that in place of the 7AL I currently have.

[Turbo Hen]

i drive on the street sometimes for hours at a time.....my car is out 4/5 nights a week & all day on the weekends. I have yet to have any issues with my Digital 7.

I would NOT get rid of any DIGITAL MSD in favor of the old school AL boxes, not to mention the 7AL's WILL NOT last on the street.

-Carm

[Adam's 55 Chevy]

Carm
Sorry I kinda led you off track with the question.

The car I bought was a race only vehicle with a 7AL currently in it. It's a '57 Chevy that has been a race car since 1962 but I want to put it back on the street for limited use to get more fun from it. I know the 7AL will burn up before the first fuel stop so I intend to sell that on with the pro power coil.

I bought a basic digital 6 and HVC coil about 4 years ago for another project but didn't use it so it is just sitting on the shelf.

I guess my question is should I sell both of these and purchase a new 7531 box with the money and learn how to use it or would the digital 6 be adequate for a street strip blow thru application? I would rather spend a few $$$ more on the right part than risk burning down a brand new motor using what I have just because it's there.

[Turbo Hen]

digital 6 would be fine for mostly a street machine.

-Carm