Megajolt/EDIS Crank-Fire Conversion

[Mark Pietz]

Thanks, bill, I was unaware of these tables. Yes, the resolution is less with mjlt, but I'm also not running FI. Mjlt interpolates ("smooths") between points, which makes the initial selection a bit more critical. I'll print out this table and compare with what I've already compiled by hand. A quick glance tells me I'm not that far off, at least for na. But why reinvent the wheel?

I'm aware of how vacuum changes from low kpa values to higher values. In creating a map, that's the one thing one must orient to is the progression from manifold pressure (and not seeing it as vacuum in terms of inches of hg) from low to high, which at 100 or so is "0", or atmospheric, which is 14.7 at sea level. It's a fun exercise build on basic points. Last night I was playing with this and ended up with 20 degrees at idle, which is consistent with 10 degrees static that I'm now running, plus the 10 degrees the factory manual indicates for the canister when max vacuum is applied. And so we go from there. I'm going to go with 32 degrees at 3k per rk and see what happens. And as you know, through the wonder of technology, I can just as easily create a comparable map from this information. Click and drag and I can run between the two to see what works best.

Anyway, my mjlt has been shipped but hasn't arrived. I was hoping to get it installed this weekend, but that May not happen now. The wiring harness is just about complete. All dressed up and nowhere to go!

edit: I printed this out and compared it with what I have built so far, and compared it with a previous map for the boosted corvair. Where we have difficulties in comparisons, your map incorporates values worked out from a/f ratios controlled by your efi map, right? I'm going to run off a "dumb" carb (efi in the future, but not for now), with sloppier a/f ratio controls (I know - carb and a/f mixture control is an oxymoron), so I'm going to have to work mine out empirically. Since it had been several years since I built a map using this program, I had to re-orient myself in equating "inches of mercury" with manifold pressure in kpa, so I could make sense of applying the published data for the operation of the vacuum canister. Vacuum in hg is inversely related to manifold pressure, while these maps are created using increasing pressure from around 30 kpa (21" hg or 4.35 psi) to 100 kpa (0 "hg or 14.7 psi. Boost is kpa equivalent of 14.7 + boost in psi). The readings on a vacuum gauge in "hg are referenced from 0, or sea level (14.7 psi). In a way, it works backwards. I subtracted the kpa equivalence in psi, from 14.7, and converted the difference, in psi, to "hg. Then I used that information to estimate at what manifold pressures a vacuum canister would begin to operate, etc., from published data. Not really hard, once you get some key data points identified.

 

[Mark Pietz]

More progress while awaiting my module. Wiring harness: blue and black wires to far right are the power and ground, second bundle from right with plug feeds the coil pack, next bundle is the shielded signal wires ("pip and saw"), plus power and ground that will go to the mjlt, which will mount inside the vehicle and under the dash. Far left bundle goes to pick-up sensor for the crankshaft trigger wheel.

Also a pic of the "dummy drive" mounted in place of the distributor. This will drive the oil pump.

 

[Mark Pietz]

Here's the wiring finished in the engine bay. I soldered all connections instead of crimped, then wrapped with harness tape, and then put looming over it all. I still need a 1" grommet for the firewall. All that's left is mounting the controller inside the cab. I plan on mounting it on the underside of the heater duct. The white tube is 1/8" nylon tubing (mechanical oil gauge) that I tapped into the huge vacuum fitting plumbed into the intake manifold. The mjlt control module contains a map sensor and adjusts accordingly.

Regarding the relay. I "repurposed" the + lead that connects to the coil & distributor and ran it back through the its loom to the rear of the engine. The hot pickup that feeds the edis system comes from inside the cab, where it can be switched and pose a potential drain if the relay somehow sticks closed when it shouldn't be closed.

 

[Mark Pietz]

My mjlt arrived yesterday. I had a problem with my laptop, which put it out of commission. However, all was definitely not lost. I pulled an old dell full-size computer out of mothballs (in the garage) and hooked it up. Wonder of wonders was that I forgot I had a duplicate copy of all the mjlt maps and programs on it! So here's what you see in the pics: the mjlt, the cable that comes with it, and hooking it all up to a 9v battery and mighty vac to simulate changes in atmospheric pressure. Absent ignition signals from being in the vehicle, this proves it is communicating with the computer and is operational. You'll see the screen shot where simply being "on", you see "manifold" pressure of a tic over 90 kpa. 103 kpa is sea level, and as I live at 2,400 feet, you see it responding to that altitude. Excellent! Also a pic of it after giving a few squeezes on the mighty vac and reducing the pressure. I have just completed compiling the first iteration of the ignition map for this 196, and it is now loaded onto the mjlt. So after I finish the installation, which is only mounting it to the underside of the heater duct, and wiring in the power/ground/pip/saw onto the molex connector, and hooking up the 1/8" nylon tubing via a short section of rubber hose, I am done installing it. Plan on firing it up tomorrow.

 

[Mark Pietz]

It runs, but I've had trouble uploading some video to youtube, so as soon as I fix whatever the problem is, I'll get it here.

The engine runs noticeably smoother. I'm tidying up the wiring, as I had a fuse problem (need at least a 20 amp fuse to run the actual coils - I was blowing 10 amp fuses). Mounted the mjlt to the top of the heater duct so it's out of the way and not visible. I left the connector cable installed and coiled up out of the way. Hot feed to the relay is direct from the battery, as I didn't figure a way to run it through "switched". So as long as the relay never fuses itself, things should be fine.

Next on the agenda is to convert Matt p.'s v8 over to this. We were talking about this yesterday, and I've volunteered to machine an adaptor to a v8 harmonic balancer to mount an aftermarket trigger wheel. As my rig is still half-apart, I'll do the mockup on mine so it will be simple to graft the parts over to his and minimize his downtime.

Edit: it is up on youtube. IH 196 with megajolt/edis ignition - youtube. Or search under my name and "IH 196 with megajolt/edis ignition". Pardon my commentary, but I was a bit excited about this.

 

[Mark Pietz]

Pick of it mounted on top of the heater duct. Power, ground and pip/saw feed are on a molex plug that will go into the right side of the unit; on the left is the rg11 plug for the communication cable, as well as the tubing into the map sensor. I took one of those standard 1/8" nylon tube brass ferrules to connect the nylon tube, screwed to a 1/8" brass fitting w/barb, short length of rubber hose into the map barb. I screwed this tubing down to the heater duct to keep it secure.

 

[Bill USN-1]

I printed this out and compared it with what I have built so far, and compared it with a previous map for the boosted corvair. Where we have difficulties in comparisons, your map incorporates values worked out from a/f ratios controlled by your efi map, right?

Did you get the tables worked out?
Your post didn' really mke sense to me.
The table is just the factory distr specs input into a spread sheet timing table.
It has nothing to do with efi.
It is map based but so is your megajolt ignition.
So other than resolution of the cels it should all be the same.

You can't directly compare to a boosted application if it is set up properly to retard the timing each 1000rpm above 100map when it will be outside the naturally aspirated range.

 

[Mark Pietz]

I didn't really express my thoughts well on this. Anyway, what I was trying to say was that you have a baseline mechanical curve and vacuum advance is superimposed upon that when running other than wot. Same for boost, except in the opposite direction, but I *think* that is simpler to begin with, as I just subtracted 2 degrees per lb. Boost, a safe place to start. I compared the curve I worked out with the 4 cyl. Map you has posted, and I was spot on in some areas, fairly close in others, so all in all, I'm comfy with where I am. Also, I wasn't deviating from my rpm bins (increments of 500 rpm) and interpolated accordingly. Your map ended at 3,600 rpm and I worked one out up to 4,500.

I inexplicably dialed in 5 degrees btdc for cranking (300 rpm and below) instead of 12 like I used before. The sudden jump to 18 degrees on occasion causes a backfire while cranking, but that's my stupidity and easily corrected. Just hook up to a laptop and click up to 12 degrees, then "save". The engine starts much quicker, though, compared with the distributor. Just a few revolutions and it's going, instead of cranking for at least five seconds or so.

It isn't efi, but it is a big step in the right direction!

 

[brained]

Completed my edis install this weekend. Super happy with it. Thanks also to bill for the timing tables.

 

[Mark Pietz]

completed my edis install this weekend. Super happy with it. Thanks also to bill for the timing tables.

Hey! Good job! Do post pics of your install - and your map! As you May have seen, last Friday I smogged my 1980 and got the plates, but Saturday I removed the smog stuff (gasp!) except for the cat, and put the edis back on. I don't recall exactly what map I used, if it was bill's or one I modified, or what - will check this evening.

My engine started well before, but now starts even better. When I first had the edis on, my carb wasn't dialed in (such as a Holley 1940 can be), but since then bushed the shaft, flattened the mating surfaces, etc. So now I'm anxious to put a few miles on it. I think I'm running 15 degrees btdc at idle. Unless you're doing efi, I can't imagine running a carb with any other ignition system than this.

 

[brained]

unless you're doing efi, I can't imagine running a carb with any other ignition system than this.

110% on this. It's the only way to go.

Here's the map I'm running after driving for a day:

No pictures of the install yet - but here is the sensor mockup on some spare parts:

And for a trigger wheel I took a deep offset pulley, cut the v-belt portion off and notched what remained:

 

[Mark Pietz]

110% on this. It's the only way to go.

Here's the map I'm running after driving for a day:

No pictures of the install yet - but here is the sensor mockup on some spare parts:

And for a trigger wheel I took a deep offset pulley, cut the v-belt portion off and notched what remained:

Re: your trigger wheel. I like! More than one way to do this! I'm going to compare my curve with yours.
Edit: did you mill that pulley your self? Nice job. I wanted to tuck my pickup coil up out of harm's way but it's difficult to access. After seeing your mount, I'm rethinking mine. Right now I'm having difficulty in getting the laptop to communicate with the megajolt (a recent major upgrade scrambled something, I think).

 

[brained]

As much as I'd love to be a machinist and fabricator, sadly no. I took it down to a local machine shop, explained what I needed and they produced perfectly.

Easiest mounting of the sensor would be at the 6 o'clock position using a couple of the front oil pan bolts, but I was afraid a stick or brush could snap up and hit it.

12 o'clock and 9 o'clock seemed kind of 'busy', lots of stuff over in that area.

So 3 o'clock it was. I wasn't totally certain on the height the sensor would need or if that height would be consistent from engine to engine. So there is lots of shimming and spacers on my current bracket.

When I get my 196 back from the machine shop I'll build a new bracket that is the exact correct height.

 

[Mark Pietz]

You discovered what I discovered. Ditto on the 6 o'clock. I did mount mine at about the 1:30 position but am going to reconsider 3:00 (probably closer to 4 or 4:30) in that I have 8 mounting holes and can make 45 degree rotational adjustments. The fronts of our engines are almost identical, at least in this area, and I can imagine how much easier yours starts. I really like slapping a timing light on it and seeing a timing Mark that does not waver in the least. None of the distributor slop.

I hope our examples will inspire others. I'd like to see this on a 304/345/392.

Do post pics of your setup as it sits in an 80/800.

Oh, and what did you do for a dummy distributor drive?

 

[Mark Pietz]

I made a copy of your map and ran it just because I could. That's one advantage of this device. Easy peasy. I get a fair amount of pinging in places I didn't before.

I believe there are enough differences in our engines to explain this. Your 196 is in a 80/800 (right?) so you'll have contour pistons and I have the flat top w/boot heel recess; I also have the quench space tightened up and a 256 grind cam, so it looks like my engine favors less timing advance. Or so it seems. I have created a new map based on the original distributor curve w/mechanical and vacuum advance (with some changes) and will be testing it out after this current rain storm ends.

 

[Mark Pietz]

Brained,
question: how do you copy (or export) that ignition map? I want to post mine here but can't figure out how.

Anyway. Today I installed my new map which is essentially an emulation of the oem curve, plus tweaks made to it after identifying - via data logging - where some pings that occur under load at higher rpms. I have a favored grade I use that reveals weaknesses in this area. I believe I am zeroing in on a final curve, and this morning drove down my hill and up to IHPA in Grass Valley. This is the first time I've driven it where I've actually felt good about its performance (for a four, that is).

 

[brained]

Image made using the built in windows 7 snipping tool, its just a screenshot.

I suspect that with my very low compression 152 I can successfully use a much more aggressive map.

My contour piston 196 is still at the machine shop, the compression ratio and cam to be determined upon my return from vegas at the end of this week.

 

[Mark Pietz]

re: your trigger wheel. I like! More than one way to do this! I'm going to compare my curve with yours.
Edit: did you mill that pulley your self? Nice job. I wanted to tuck my pickup coil up out of harm's way but it's difficult to access. After seeing your mount, I'm rethinking mine. Right now I'm having difficulty in getting the laptop to communicate with the megajolt (a recent major upgrade scrambled something, I think).

Just an update. I need to smog my Scout within the next couple of weeks and removed the crankfire system, except for the trigger wheel, of course. Very easy as it is essentially modular and I only have a couple of wires that go through the firewall. But when I put it all back on after smogging, I've decided I am going to relocate the trigger wheel pick up. Mine is tucked up on the cam gear cover at about the 2 o'clock position if you face the truck. Access to the pick up is a pain and I'm going to try to relocate it further down around 3 or 4 o'clock like yours. I assume you've not had problems with yours getting hit with rocks or debris. Do you happen to have a pic with yours actually installed?