Need the ability to set timing tables and have the timing controlled electronically,

Would like to hear from someone running this box and what your experience is with the box,

Did you phase the rotor and did you go to the larger cap for the Dissy?

Neal

 

I am going to use this on my ZZ383, but before I tried this new to me ignition system I install this on my 78 L48. So here is what I know so far.
1. you need to lock out all mech / vac advance in the distributor. I am using a MSD 85501, which has no mech / vac advance.
2. You need to set the static advance to the max you want to use because the controller only retards the advance. ( max retard is only 25 degree's

3. You need to add a MAP sensor 1 BAR if using a carb, or 2,3 bar if you have any forced induction / efi etc. If you need a 1 bar then you need to purchase a GM 1 bar sensor and modify the connector to remove some plastic keys so the connector from the MSD will plug in.
GM PN 12569240
http://www.gmpartsdirect.com/results...umber=12569240
@ $95 dollars (canada) worth finding one from a wrecker. I could not find a wrecker part where I live. The map sensors is used similar to the vacum advance. Has it's own retart curve.

4. You need to get a USB to serial adapter for your PC. Not all work so it would be worth buying the one MSD recommends. My first one only worked while the car was not running. The second unit worked OK.

You can map out any timing table you want as long as it is within total 25 degrees retard, and that includes from all the timing retard tables.

There are many other features more for the DRAG racer which I did not play with but you can read the complete manual online.

Rev limiters etc.

As far as a adjustable rotor to deal with rotor phase I have not yet checked to see if I need one. But it is worth checking to see if you need it.

My biggest problem with the unit was getting the PC to connect while the engine was running.

What type of application are you looking for. If for street performance over the stock HEI, it isn't worth the trouble you wont see any improvement in drivability or performance. If you have a speacial need for racing / track etc you have alot to play with to dial things in.

 

cagotzmann; thanks for taking the time to type all that info, just what I was looking for.

The 25* max may be a problem, looking to run 36* plus 12* vacuum advance, that's 48* total. If it will only pull out 25* then that still leaves 23* at start up, not sure how the starter will handle.

I'm running a Data logging program so I already have the MAP sensor mounted in the car. Do you know if the Box has an internal 5 volt supply for the sensor? I had to make one to drive all the sensors for data logging.

I see on MSD's web site they offer the cable for connecting the box to a laptop from a third party vender. Did you purchase your cable from the recommended vendor?

I downloaded the Pro-Data Software and have been playing with it some. Looks fairly straight forward and easy to navigate around.

Trying to do all my research prior to calling MSD Tech so I have all my questions ready to go.

Car is street/strip and really like all the functions and easy programming with the laptop that comes with the Programmable Box.

Thanks Neal

 

The MSD unit supplies power for the MAP Sensor. The USB to serial cable MSD recommends I could not find local so I purchased something else and seems to work got lucky the first brand didn't work (Star tech) Tripp-lite keyspan unit worked, but if you can find there recommended cable I would just do it.

48 degrees total is alot of advance. The stock HEI system at WOT is usually only 36 degree total because at high engine load there is no vacuum advance. Vac adance is usually only at idle and light load cursing situations (lean AFR) requires more advance (rich AFR) requires less advance. At 48 degrees rotor phasing is a problem and most likely will get cross fire to the wrong plug.

Each plug is a 45 degree rotation on any size dist 360/8 cyl = 45 degree's the camshaft speed I know is not the same as the crank but I think its 1/2 crank so at 45 degree BTC would be about 22.5 degrees at the distributor which is half way between 2 towers. The ignition will take the shortest path so which plug fires ?. That is why rotor phasing is important and usually max advance is never much more than 36 degrees. = 18 degrees at the rotor, always cloesest to the plug you wish to fire. This problem goes away with a rotorless ignition system / direct coil per plug and uses crankshaft sensors.

 

I need 36* plus 12* vacuum for a total of 48* from what I understand normal advance with vacuum in some cases can be as high as 52* total.

You bring up a good point that I was not thinking about, timing at cruise may not be at full mechanical so even with the vacuum it may not be at 48*.

I know there are guys out there that have their dissy set up to pull full timing at 38* in by 2000 rpm, and when you add 12* of vacuum on top of that you end up at 50* total with no issues at all at light cruise.

I wonder how they are getting away with it set up like this?

Thinking about phasing you really only have to compensate for the total timing swing from lowest to highest. Say your lowest setting is in the 20* range (idle) and your highest is in the 48* range then you only need to be in the 28* range for phasing. If you run the large cap dissy then the distance between the terminals is greater then the small caps dissy and arching is less of a problem.

Neal

 

This is good reading about what the stock units do
https://www.corvetteforum.com/techti...=115&TopicID=3

If you need more than 38 degrees and to emulate the stock HEI, I dont think the MSD 6AL programable will work. I think this unit is more for the drag racer / WOT driving than it is for street and fuel economy that the stock HEI with mechanical & vacuum advance are designed for. I called MSD to confirm max retard of 25 degrees only. I dont see how you are going to get this to work. I am using my car for Road Track driving so fuel economy is already gone.

I may need to go to the bigger cap as well.

Have you seen this video

 

Thanks for the link to Lar's paper and to the video, I had seen the video, it explains Phasing in detail.

I'm approaching the conclusion you have that this box will not allow me to set the timing tables I would like to try.

Thanks Neal