Megajolt/EDIS Crank-Fire Conversion

[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?