Its hard to find the one bar sensor these days, you can use a two or three bar sensor since you are not using boost, they all seem to work the same when using them to measure vacuum. I've set quite a few of these programmable 6AL units up now, they are a great bit of kit! Using vac advance is a great idea for a road based car, also using the non-timed port is a good idea, the timed port was an emissions 'dodge', its not what the engine wants. I always program in a flat line with no spark delay at all to start with, I then twist the dizzy around and listen to the idle speed, I'm looking for the fastest idle I can obtain, I then make a note of the actual timing figure, depending on the cam this could be quite high. The last SBC that I worked on wanted an idle timing figure of 30 degrees, it would almost stall at anything less than 26 degrees. Now the all-in figure for a SBC is usually around 36 degrees but this does not mean that I was only running an advance curve that was only 6 degrees wide. I set the vac system up to add 14 degrees of timing, the remaining 16 degrees was obtained from the RPM timing curve. This allowed the engine to idle with 30 degrees advance but if the throttle was pushed approximately half open or more the vac system would pull out 14 degrees. The RPM curve could add another 20 degrees to the 16 which would give the 36 degrees that the engine wants at high RPM with the throttle wide open. (The 14 would NOT be added to this figure). At high RPM but with the throttle just cracked open the engine would run with 36 + 14 degrees of timing giving 50 degrees in total, the dizzy needs to be set to that it is at 50 degrees, the MSD actually works by 'adding' a delay to the 50 degrees, in other words 'pulling' timing out of the system. It took a while to figure all of this out and what does not help is the fact that I normally work with inches of mercury when looking at the vacuum figure but the MSD software uses PSIA. I ended up using a vac pump connected to the MAP sensor so I could work out what certain inches of mercury figures are in PSIA. The real-time MSD software helps when doing this.
Thank you for posting this, great video.. I've been trying to program my 6AL-2 controller. I have a 406 SBC in a 1972 Camaro. I've gotten the basic timing set, the distributor is locked at 38 degrees total advance, Advance at idle is programmed at 17 degrees, all in at 3000 rpm is set at 36 degrees advanve. I followed your method, and read / used the instructions in the bulletin you showed, I found it on line and printed it out. Seems whatever I do I am not able to get the engine to advance over the 36 degrees of all in mechanical advance setting. I did record that before I locked out the mechanical and vacuum advance, I had total advance of 52 degrees at 3200 RPM, setting in my shop using my timing light. I'm sure I'm doing something wrong, I just don't know what. I have called MSD twice and have gotten conflicting information. So, any suggestions from anyone would be greatly appreciated.
Thanks for the video. Just a quick question. Are you adding the 10 degrees your pulling with the map sensor to your locked out base timing? If you had 30 degrees base are you moving it to 40 degrees to get back down to your all in timing?
You can only pull with the box. It can't predict the future and advance timing. You have to set the full advance you want to ever see, then subtract from there.
Interesting video. I thought with the 6530 you set total timing and then kind of work backwards by retarding the timing with the computer. Do you have to do it the way you described for this box? I don't have this box but am considering it, so I'm just doing my research. Thanks from NB.
Yes you are on the right track. Firstly I'm no expert and found setting up the timing curves quite confusing in the past as they are called RETARD where as I am used to to concept of Advance/Retard in relation to TDC. The point to take on board is that RETARD is now in relation to ALL In TIMING (Static+RPM+VAC timing) being the trigger point for this system. eg. Assume we want say 14 degrees of Vac advance and 16 degrees of RPM advance this would equate to 30 degrees of TOTAL CONTROLLABLE TIMING. To convert our desired RPM and Vac Advance and apply to the RETARD curves just subtract each value from the Total Controllable Timing. i.e. 16 degrees of RPM advance now becomes 30-16=14 degrees RETARD. Feels really arse about face and messes with the mind. Hope this helps. Also read online.fliphtml5.com/uhex/shun/ which is shown in this video.
Yep. That's the way it works. Can be confusing at first, but you'll catch on quickly. I use mine with a crank trigger setup. Most stable timing I've ever had.
THE ABSOLUTE MOST BADLY MANAGED PRODUCT BY MSD CONFUSED as well Do the graph reads use crank or cam degrees .?? eg If I were running max 50 degrees advance mech advance 35deg tot vac advance 15deg split 2ways Graph A/ mechanical advance initial +mechanical = 35 degrees So max all in advance by 2500rpm would read in MSD Speak 15deg at 2500rpm removed [allowing 35deg of eng timing ] Graph b/ vac advance start at 15inch hg ,,, 15 deg adv [msd 0 deg retarded ] finish at 10inches hg 0 deg advance [msd 15 deg retarded ] NB starting no. eg might be vacuum reading ,at start 40mph -- finish at 50mph does this sound correct
