Having some ignition related issues

[JeepsAndGuns]

So here's the deal, pretty much since I have done my fuel injection conversion, I had had what almost sounds like a slight, very fain miss when engine load is very light. (like when coasting down a slight grade where the throttle is close to being closed) Basically high vac areas where timing is higher. When I did my conversion, I never did re phase the distributor pickup. I figured it was simply because of that. I procrastinated for several years and then last weekend I for some reason decided to finally do it. I followed the instructions from from a few different places. I pulled the dist, reluctor, drilled and tapped it for a set screw, and re phased it. I put it back in as close as I could to where it was, knowing it was going to need to be re timed. I run it down the road and back to get it warm to set the timing. I could tell the timing was off and it did not run well. Once I got back, I shut it off, disconnected the bypass wire and tried to restart. I had a hell of a time getting it started. Then when it did start, it would run about 20-30 seconds then die unless I held the throttle open. I could not even move from the seat to the engine before it would die. I placed small shim between the throttle arm and stop screw to try and hold it open a little. I was finally able to get it to run long enough to try and set the timing. I would watch the timing mark and after a few seconds, the timing mark would disappear, the engine started running super crappy and then die about a second later. I would have to restart (not easy) and then run up front and get a few seconds to try and set the timing before the mark would disappear and engine die. After a few times of doing this I think I was able to get it pretty close to zero. I shut it down, unhook the battery, reconnect the bypass and then test run it. It seemed to run somewhat ok.
I drove it down the road and back but it did not feel quite right. It has now started to want to have a slight backfire when shifting gears, and now for some reason, DFCO does not want to engage all the time, and when it does, it exits it sooner. Idle was also not the best. I double checked the phasing and it seemed ok. I thought maybe I hit or damaged the pickup somehow. So I order a new one up from rockauto and put it on yesterday. Well that was a failure, it would not even run on that pickup. When I tried to start it, it would kick back, and when it did finally start, it was very badly, popping and backfiring out the exhaust and would not rev up. Now I had that exact same issue when I first did the conversion years ago, and it was the cheap parts store pickup that was in the distributor. I installed a top of the line napa pickup and all was well, and has been well ever since. So I pull it back out again and put my old pickup back in.
It was hard to start but finally did. It ran a little poorly for a few min but then started smoothing out as it warmed up. I drove it down the road and it it still does not feel right. DFCO does not want to engage and it still has a slight backfire when shifting. Also, since dfco is not engaging, during decel it wil blop blop, blop, out the exhaust. It has never done that, even when everything was running normally. I get back home, and try to set the base timing again, but the engine will only run about 10-20 seconds then die when the bypass it unplugged. I plug it back in, reset the ecm by unhooking the battery and restart. I fool around with the timing manually with the bypass plugged in and just did it by ear and got it back to running a driving about 85% normal, but something is still not right. DFCO is still slow to engage, and does not engage all the time like it used to, I still get a slight backfire when shifing and the blop blop blop during decel.
I think it is all coming back to some type of ignition related issue and I can not help but think it might be the motorcraft dist/pickup. Especially after I re read Dr_Grip's thread: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4419-TBI-conversion-on-a-Ford-400-need-help-getting-it-to-run/page3
So my current idea is to ditch the motorcraft distributor and pickup and try to use a GM based or hybrid distributor. I remember seeing a few threads on a couple different forums where there was a place that could take your carb distributor for any engine, and graft on a GM FI distributor top half (take two and make one) But I can not find any place online that does this. The other option I see would be to buy a aftermarket HEI distributor for my engine (they are all over ebay) and mod it with a 7 pin module just like Dr_Grip did with his ford engine.
I would prefer the TBI style dist top (that uses the 8 pin module) on my old dist bottom, as that way I can use a good quality factory gm pickup and it will be what this ecm had factory.
I am not a huge fan of the HEI coil in the cap distributors, but would run one if I could come out money ahead of above modded dist. Only issue I see is questionable quality of the aftermarket hei distributors and parts (pickup, coil, reluctor, etc..) But I suppose all that could be swapped out for quality parts, assuming stock gm parts will fit the aftermarket dist.

So just looking for any and all input, theories, ideas, recommendations, etc.. Thanks.

[dave w]

I've done a couple "non-GM engine" TBI conversions using the services of Dave's Small Body HEI's: http://www.davessmallbodyheis.com/

dave w

[1project2many]

Have you watched a datalog as this is happening? You might get some idea of what's going on by watching the DFCO parameters. Is there any chance you're have a problem with the MAP sensor? When DFCO is active there should be no way for popping to occur as there shouldn't be any fuel delivered.

This type of problem is often best found with a scope. Watch the pickup coil voltage and the REF signal to the pcm to see if there are any strange signals. Watch the coil to see if it's firing correctly and regularly. Check for stray pulses or random spikes in rpm if there's a problem with the Motorcraft parts.

Looking at pictures of the HEI distributors for AMC engines, it seems like converting a small-cap HEI might not be that difficult.

[JeepsAndGuns]

The DFCO issue does almost sound like a MAP issue, just odd it started right after I re phased the distributor. When it does enter DFCO, it does not do any bloping, that is only when DFCO does not engage. When it engages it goes full lean like it should, but seems to exit at a higher rpm that is used to/programmed to. DFCO is not set to become active until the engine reaches 100*. Before, it would just decel, no blopping or popping. Now when it doesn't engage I get the bloping and popping.
I did not hook the laptop to it when I was messing with it, as I got too irritated and just quit for the day. I won't have a chance to do anything with it until this weekend. But I will definitely hook it up and see if I can see anything out of the ordinary. I have a couple spare map sensors, in case I see the one I have doing anything funky.
I wish I had a scope or had access to one, however I do not.
I am still strongly considering ditching the motorcraft and switching to a HEI. I thought about buying a cheap one and swapping all the guts to quality stuff, but then I thought if I bought a decent one to start with all I would have to swap out is the module. How does everyone feel about mallory? http://www.ebay.com/itm/AMC-360-401-V8-Mallory-High-Energy-Ignition-HEI-Distributor-8560001C-/252191050981?hash=item3ab7c20ce5:g:OPMAAOSwZjJU4md S&vxp=mtr

[sturgillbd]

I have had decent luck with Mallory distributors. Summit has that distributor on clearance for $179. http://www.summitracing.com/parts/maa-8560001c/overview/make/american-motors.
Here is another cheaper option: https://www.pricefalls.com/product/amc-jeep-290-304-360-401-race-pro-billet-aluminum-distributor-red-cap/60369377?source=GoogleShopping&medium=cpc&term=PLA-SC&content=88932797071product_type_l1automotive%26cus tom0p350100&campaign=RevsAutoParts&adpos=1o1&creative=66622560511&device=c&matchtype=&network=g&gclid=CLqRiI6Ky8kCFdgPgQod4fULVA
That was a quick search. You may find it cheaper. I know of a few people running ProComp distributors with a MSD 6AL and have had no problems. It is chinese made but a lot of the aftermarket parts are anyway.

Just another option to weigh out.

Brian

[1project2many]

All the HEI distributors I see are non-computer controlled. So you buy a distributor, then you have to remove the module, grind a notch for the computer harness, obtain said harness, replace the module, and secure the mechanical advance... that's a lot of work after shelling out cash. And to top it off that coil in cap distributor is kind of oversized for the space available, no?

Where can I find measurements for the AMC distributor? I dunno if there's another one that's close but there's a chance. What about installing the GM pickup coil and shaft in the Motorcraft distributor?

I'm trying to find a few pictures. I just got home and I've got a few minutes before I head out into the yard for chores. If you know of any reference info for sizes etc I'll gladly take a look.

[JeepsAndGuns]

The HEI will fit and clear the engine and surrounding parts. It's close, but does clear (it's a popular swap for these engines). The work needed to mod one is not really any different than what I had to do to my current distributor, and it really was not that bad. I am pretty good at fabbing a modding. So that does not bother me. Now attempting to install GM guts into my current distributor would be a whole different ball game.
What measurements exactly are you wanting? Are you wondering if any other OEM distributor could be machined/modded a little to be a drop in? Or are you wanting clearance measurements from distributor to other items on the engine?
I am currently running the ford TFI style riser and cap on my stock distributor, and that puts it close to the same diameter as a HEI. It's not the best picture, but you can kinda see it here: http://img.photobucket.com/albums/v606/JeepsAndGuns/2012-04-07182041.jpg

Doing some more google searching and reading. I think I may get one of these instead of the more expensive ones. http://www.skipwhiteperformance.com/detail.aspx?Item=6512-B
Most forums I read where people have used these from that place seem to really like them and have no complaints other than a a few here and there that most than likely got bad ones.
I have also been searching for what vehicles have the 7 pin module to see if I could source some cheap from a JY or buy new. It looks like the cadillac 4.9 V8's from the early 90's have them, and my local pull a part JY usually has several of them at any one time. So I should be able to pick up a couple of those complete distributors for really cheap. That way I could source the module and connectors, and probably a couple good pickup coils to use in the aftermarket AMC HEI.
At first I didn't like the idea of the HEI and everything (coil and module) all in the distributor and cap. But now that I have thought about it a little more, I think I am starting to like the idea. It would kinda clean things up on my engine a little. Right now I have the 8 pin module bolted to a large heat sink that is then bolted to my AC compressor. And the coil is behind that. Moving all that to the distributor would tidy things up some. I may hit up the JY this weekend.

[1project2many]

The goal was to try and find a path that was less work and made more sense than disassembling the aftermarket distributor and replacing or disabling most of its parts.

When I asked for distributor dimensions I was looking at maching a GM unit to fit in the AMC engine. Since then I've looked at enough pictures to get an estimate of what's involved in that swap. The next approach to find an easy swap would be to use GM guts in the AMC distributor. I think a points distributor would be a good starting point and I'd try to get a used $5 - $15 small cap HEI from Ebay for the GM parts. But ultimately, that would probably require as much work as converting the aftermarket large cap distributor to ecm control. It would result in a unique conversion using a remote coil system but that might not be a strong enough motivator to try this path. Especially when you consider that there are remote coil kits (http://www.speedwaymotors.com/MSD-8401-HEI-Coil-Conversion,674.html) to move the HEI coil out of the big cap.

[JeepsAndGuns]

Well I think I may have a update. Now I am starting to think I have some other type of issue.
I finally had a chance to hook it up and watch the data stream. Right away I notice a higher than normal MAP. I go for a short trip down the road and notice the map readings were way higher than what I remember. It has been a long time since I have had to do anything to it or do a log, and it looks like I have deleted any older logs I had. But I do distinctly remember I used to idle around 40-45 kpa, now it idles at around 50-55 kpa. It also stayed higher than normal at startup. I was having some laptop issues (didn't want to connect) and did not get to watch a cold start, but it will surge some at cold idle now, it never used to do that. AFR will also rise and fall with the change in rpm. I shut it down switch laptops and finally get it to connect.
While watching the data, it seems map is higher that I remember. I can not remember 100%, but it seems to be around 10kpa higher across the board than I remember. I suspect maybe the map sensor. I figure higher map readings could cause some of my issues, making the ecm think its under more of a load than it is, which effects timing. I unhook the ecm, swap out the map sensor for a spare used one I had (both old and new are original gm parts) I hook the battery back up then give it another run. Still no change, map readings still the same. I drive down the road a couple miles and record the trip back home. Just fyi, at the end I am doing some slow speed parallel parking without touching the throttle, so if you see some odd readings there, that's probably why.

[dave w]

I did not have much time to look closely at the 12-12-15.xdl file.

I attached a few screen shots of what I was looking at. I find Mode Word 2 & EGR & Spark Mode Word bitmasks data the most interesting.

Maybe review the EGR delete parameters?

dave w

[JeepsAndGuns]

Not really sure what those bitmasks mean.
I have no egr on this engine. The only egr parameters I remember changing is I set the egr enable temp to max. (but I did change the required parameters to allow WB data logging through the liner egr input). I just did a compare and it looks like I changed the "desired egr vs rpm vs vacuum" table to all zeros also.

So after posting the update, I went back out with a can of carb cleaner and checked for vacuum leaks. I could not find any. I then checked the timing with my timing light. I just left it as is (did not disconnect the bypass wire or anything) and it was bouncing between 5 and 10 degrees. This should not be right as I have my bin set to where I should be getting roughly 24 degrees at idle. At some point in the past (not sure how long, but quite some time ago) I did verify it and I was getting what I was supposed to. But I have not checked it in a couple years or more.
When I built the timing table I emulated and made small adjustments until I got the best vacuum and idle quality, then built the rest of the table from that. (this AMC engine loves timing btw) Now I know timing can and will effect vacuum. So now this has me leaning back twards a timing issue. My current theory says if my timing is for some reason ~10* less, that could maybe be the reason for the higher idle map and maybe all around map? This in turn would effect when my dfco comes on and turns off, since it is map based.
So now I am back to thinking something screwy is going on with my timing, because of all the above mentioned issues and all the extra popping/mild backfiring when I shift and when in decel (as it never did this before)

I went to the JY this morning and picked up a complete distributor out of a 4.9 cadillac, and also a couple extra 7 pin modules for pretty cheap. I have already gutted the distributor for the module, connectors, and pickup. I also cut a hole in the old cap to be able to see how it was phased from the factory so I can set the new dist accordingly. I think I am going to wait until after Christmas to order the aftermarket hei. That way I hopefully avoid the holiday shipping rush.

[dave w]

Sometimes the bitmask data will help figure things out when troubleshooting. Looking at the data log, after its been exported to a .csv file, can help make sense of what might be happening with the other parameters when troubleshooting.

I agree, the changes to the distributor is the most likely reason the engine is running different. I like the plan to order an aftermarket distributor.:thumbsup:

dave w

[JeepsAndGuns]

OK, I got the new distributor in and have hit a snag. It looks like it is not going to be as easy as I had originally thought.
I had read a few writeups online from other people converting 4 pin hei distributors to 7 pin. They simply drill and tapped a new hole for the 7 pin module and then just hooked everything up. Seemed pretty simple.
So I get the new dist, pull the cap and module, only to find the 4 pin module is on a sort of pedestal. I test fit the 7 pin module and the hole on the power side lines up fine, but the hole on the reluctor side is completely off the pedestal, there is nothing there to attach to. CRAP.
So I started brain storming. One interesting thing I noticed about this distributor is that it is two piece. The "top" is separate from the shaft/base. The same company that makes this distributor, also makes it for many other non GM engines. My guess is they make it two piece so they can cast and machine the "top" and have the same one for all, and then simply make the shaft engine specific. Makes sense if you think about it.
So I gut and completely disassemble it. So here are my 3 original ideas:
Idea 1: Since I have the old cadillac 4.9 distributor I gutted for parts, cut the mounting "pad" out of it, mill down the height of the "pedestal" and then mount the 7 pin pad to the old 4 pin pad. I would have to counter sink a screw under the module to be able to hold the new pad to the old one. This method seems time and labor intensive.
Idea 2: The second idea I had was to make a "new" top. Doing some rough measurements, I might be able to take a GM distributor, chuck it up in a lathe and cut off the "top". Then simply dill 4 small holes and mount it to the "shaft". I have found a complete (minus the cap/coil) distributor from a TPI 350 on ebay for only $15. So I am waiting for it to get here and I will measure it and get a better idea if I can do it.
Idea 3: Locate/buy another AMC hei distributor and mod it. (like the one linked to in post #4) Only problem there, is without seeing it with the module removed, I would have no way of knowing if it would be any different than what I have. There is the chance I could run into the exact same issue. Not to mention it is about 3x the cost. of what I have now.

So far I am liking idea #2 the most. If it fails then I think I can make idea #1 work. And before someone mentions the cost of machine work. I have a smithy granite 1324 combo lathe/mill. So I can do all the machine work myself.

http://img.photobucket.com/albums/v606/JeepsAndGuns/20151229_064157_zpst0u4zflq.jpg

[1project2many]

I think adapting the top of a GM distributor has promise.

[dave w]

Maybe this is the 7 pin module you need?

dave w

[fastacton]

Most of the distributors I've modded have had that problem. I've just drilled the new hole off the pedestal and used a longer screw. It's not the prettiest, but it can't be seen when it's back together, so it doesn't bother me. You can also use a counterbore to take part of the pedestal off (centered on where the new hole will be, so it will be a half circle) and then use some stock to fill that area plus enough extra to give a flat surface for the new hole. Which brand of distributor did you get?

[dave w]

Maybe this is the 7 pin module you need?

dave w

I should have made some measurements before posting.:homer: The 7 pin module has a different bolt pattern than the older 4 / 5 pin module.

I like the idea of re-purposing / modifying the top of a GM distributor to fit the base AMC distributor pictured in post #13.

dave w

[JeepsAndGuns]

Most of the distributors I've modded have had that problem. I've just drilled the new hole off the pedestal and used a longer screw. It's not the prettiest, but it can't be seen when it's back together, so it doesn't bother me.

I thought about that too. However I chose against it because I feared that when I tightened down that screw, it might put a strain on the module and crack it (since that edge of the module is no longer supported)
I was off today so I played around with the junk cadillac distributor. I cut it off and machined it down and have it to where it will set down on the base/shaft. It actually matches the top I took off almost exactly. I'll try to get a couple pictures of it tomorrow.

The distributor is unfortunately a china one. I purchased it from a place called skip white performance. It did not have any brand on the box, so I had to googe a little bit to find it. It looks like it is a company called TSP (top street performance)

[fastacton]

I carry TSP parts in my shop. Overall, they've been pretty reliable, although there's an occasional bad ignition module. They have a 1 year warranty on all of their products now and they are good about standing behind their parts. I'll be interested in seeing how your top swap goes. That does sound like it could be a good way to go for some applications.

[JeepsAndGuns]

Here is the cadillac distributor top next to the aftermarket one. It was really pretty easy to machine. I just cut the shaft off with a hack saw, then clamped down on the top from the cap side. There was a machined surface for the cap that made holding it in the chuck pretty easy. I took off as much as I felt comfortable with without making it too thin. It has ended up being a hair taller, but I do not think it would make a difference.
Its kinda funny just how closely the cadillac top matches the aftermarket one as far as height. This was one of those distributors that also had the 1x reluctor and pickup in it. So that is the reason it is taller, cause the actual pickup was pushed lower into the distributor. When I install the aftermarket shaft, it raises the pickup back up to normal height. I would also have to figure out how to hold the pickup in place. The roll pin that held it originally is now way too low. I'm thinking I could remove it, tap the hole and use a long machine screw to keep it from rotating.
Only two things I do not like about this top, is the large opening in the side (you can see at the bottom in the first pic) and the 4 large holes in the base. IIRC, I think there might have been a plastic cover on there. The 4 holes in the base had a steel mesh screen covering them. I suppose I could simply reinstall it. I am going to keep this as my backup in case the TPI distributor top does not work out. Still waiting for it to get here.

http://img.photobucket.com/albums/v606/JeepsAndGuns/20151229_184324_zpsrexln42a.jpg

http://img.photobucket.com/albums/v606/JeepsAndGuns/20151229_184340_zpswhjbsvtn.jpg

But I may have run into a issue with my engine. I might have a mechanical issue after all. I will be making a new thread for it.

[1project2many]

The four large holes in the bottom are vents. Larger is better here... it helps dry out moisture and helps keep flammable crankcase gasses from accumulating in the cap.

The roll pin could be replaced with a longer one? Or the machine screw. If you cut the head off the screw and epoxy it down then pickup coil replacement might be easier.

[JeepsAndGuns]

Another couple updates. I got the tpi dist in and disassembled it. It was really clean and looked like a low mileage unit, almost a shame to dismantle it, but it was only $15.
The shape of it and the top are much different from the cadillac one. I could cut it down to the proper height, but would have to bore out the center part and then there would be no way to screw it down to the aftermarket shaft. I would have to weld it, which I don't really want to do. So I think I will stick with the easier to mod cadillac top.
I decided to use the tpi pickup coil because it was so clean and already had the correct terminal on it for the 7 pin module. Plus oem gm always beats aftermarket china for quality. I test fit it and it fit perfectly, however I made another discovery. The reluctor wheel on the aftermarket shaft is slightly larger than a factory gm wheel, and it hits the tip of the teeth in the factory gm pickup. Well I want to be able to use stock or stock replacement parts, so I remove the aftermarket reluctor and rotor mount off the aftermarket shaft, and do the same for the tpi shaft. I press the gm reluctor/rotor mount onto the aftermarket shaft and test it. Perfect. I install a rotor and a cap I cut a hole in to check rotor phasing with. I find the rotor is too high. I start inspecting things and find that from the reluctor wheel to the rotor mounting surface on the tpi reluctor is about 1/8in higher than the aftermarket reluctor/rotor mount.
Since the pickup coil mounts to the aftermarket shaft/base and not the "top", I should simply be able to raise the top by 1/8in to correct the height difference. A test fit showed no ill effects. Only thing it effects is the wires between the pickup and the module, and there was plenty of slack to do it. Now all I need to do is either make a spacer, or get another cadillac dist and start over, as I know I shaved at least that much off it to try and get it to the height of the original aftermarket "top". Gonna try making a spacer first.

[JeepsAndGuns]

It's been slow moving.
I was unable to make a spacer to my liking and was having a hard time marking and drilling the holes to mount it to the aftermarket shaft. Also if you look inside the cadillac top in the above post, you will see a slight raised lip. This was where the cadillac pickup coil set. This raised lip was in the way of the screw holes. It was going to be a major PITA to try and chuck it up from the bottom side to machine that off.
I pretty much got mad at it and shoved it all to the side. I then took the TPI housing, kinda rough measured, and cut it off with a hack saw. I then drive the busing out of it and chucked it up in the lathe. I bored out the center of it to where the aftermarket shaft was a snug slip fit. I then trimmed it down to where the pickup coil mounting surface on the aftermarket shaft and the TPI housing were the exactly the same. I them took and drilled/tapped 4 holes 90* apart on the tpi housing. I then drilled some little "divots" into the aftermarket shaft for some set screws to tighten into. I then added some locktite "bearing mount" to the shaft and set screws and pressed it all together and tightened down the set screws. (yes the set screws are too long, but that was all fastenal had in stock when I stopped by)
I then welded the tpi reluctor/rotor mount to the aftermarket shaft and assembled everything. All I have left is to pull my old distributor and swap over the gear, then wire it all up.
I am hoping to be able to get it done this weekend.

http://img.photobucket.com/albums/v606/JeepsAndGuns/20160108_170357_zps8gimxriu.jpg

http://img.photobucket.com/albums/v606/JeepsAndGuns/20160108_170418_zpsej6gx1h5.jpg

http://img.photobucket.com/albums/v606/JeepsAndGuns/20160110_165113_zpsntcdqain.jpg

[1project2many]

Looks nice. That'll teach that aftermarket distributor not to give you a hard time. ;)

[JeepsAndGuns]

OK. I finally was able to get it installed and wired up today. Had to extend the wires for the module and change the connector to match the new distributor. Also had to extend the power wire and chane the connector on it also.
Well it fired right up (thank god...lol) I let it set there at idle until it warmed up and then shut it off. I unhook the bypass wire and go to set my base timing. It starts up fine and seemed to run ok with it unhooked, I get around to the front, pick up the timing light and it dies. It cranks right back up and does the same thing. Runs about 30 seconds then dies. It doesn't spit or sputter, just kinda shuts off.
I was having this issue before the swap. It will actually run somewhat ok with the bypass wire unhooked now, where before it wouldn't. But it still shuts off, and I still can not check or set my base timing. When I installed it, I placed the engine at TDC, then dropped in the distributor with the rotor facing #1 and then pulled the rotor and lined up the reluctor teeth. So the rotor is facing #1, the reluctor teeth are lined up and the engine is at TDC, so I shouldn't be far off, but I can not check it.

So what could be causing this? We have eliminated the ignition module (It's a completely different module than what was in it, 7 pin now, 8 pin before), the pickup coil (used the good factory TPI pickup instead of the china one), the reluctor phasing (used the TPI reluctor/rotor mount on the aftermarket shaft), the ignition coil (actually used the china one, which seems to work fine). So everything in the ignition system has been changed except for the spark plugs and wires. What else could there be? The ecm?

After not being able to set the timing, I unhooked the battery to clear the ecm and hooked the bypass back up. I took it for a test drive and it seems to run ok. However I still get a occasional backfire when I shift gears. It does not do it every time now, only every now and then. DFCO seems to function normally again and I did not notice any blop-blop-blop during decel when dfco was not engaged.
So it seems some issues have been fixed, but some still remain.

[1project2many]

Hard to say. You can wedge a small piece of paper between the throttle stop and the set screw to hold the throttle open slightly while setting timing. After that, I'd probably monitor spark and the REF line with a scope (yep, there it is again) to see if there are any problems showing up. After that I'd be watching the MAP, O2, and TPS for issues.

[JeepsAndGuns]

Well, unfortunately I do not have, or have access to a scope. All I have is a multimeter.
Could it be a wiring issue? Maybe high resistance in one of the wires?

[Dr_Grip]

The pedestal looks similar to the one in the Skip White dizzys. The plastic positioning pins are the same on the 4-pin and 7-pin module, so you the module position is set as it has to be. Then you just drill holes into the distributor base whereever the mounting holes of the seven-pin module line up and use extra long screws combined with washers to secure the module from below the dizzy.

EDIT: Missed a page. You already are past that stage. Move along...