MPS, Rebuilding the MPS Options

[Ron914]

Hello to all who have helped me with this project . @emerygt350 ,@TJB/914, @Superhawk996 , @ChrisFoley , @rjames , @MDTerp
I am in the middle of rebuilding my MPS and have a couple of comments and questions .
First when I opened up the unit I found the most difficult job was removing the rivets holding the two halves together.
When I removed the retainer plate to take out the old diaphragm it was in two pieces .

I needed to take two measurements since I was replacing the stop screw , I needed to measure the the stop screw protrusion into the housing . The instruction sheet sent to me by a member had the measurements he must have made when rebuilding his MPS . His stop screw protrusion was 1.97mm and mine only measured 1.72mm.
His inner/outer screw assembly depth in the old diaphragm measured 6.51mm .
Here's one of my questions ?
when I measured mine I got two measurements depth to inner/outer screw assembly was 4.03
and depth to the washer outside the inner/outer screw assembly was 5.46mm.
Again there is a difference and since mine was never accessed before (epoxy over screw was not disturbed) is the difference in measurements ok and which measurement should I use I will try to attach a photo or two to help with my question.
this one .

I have not touched either of these measurements yet and awaiting any help/comments.
I think it's this one to the washer on diaphragm .

[Superhawk996]

This is going to be a tough love post.

When you encounter a problem - don’t run off like a squirrel on meth and start changing and swapping parts. You’re getting distracted and confused by all kinds of parts changes and assumptions. The random changes to timing and/or retard aren’t helping.

You should have visually checked and verified spark at each plug before jumping to conclusions and swapping from Pertronix back to points. Maybe I’m misunderstanding what led to that decision.

There is nothing going on in the distributor cap that would have changed overnight / since the MPS swap that would account for the behavior you’re describing. Could be as simple as the cap not having been properly seated or bumped during the MPS removal / install. Again I’m probably not understanding all that happened.

There is literally no telling what’s going on after all that chaos.

When you encounter the unexpected - go back to the basics. Avoid the urge to start swapping parts. Change one thing at a time. If it doesn’t help, revert to the original condition and don’t keep stacking changes.

The basics:

1) Spark. Visually observe spark at the plug. Set static timing at 7-8 degrees if the points are still in there. If you don’t know how to do this - ask and we’ll post instructions or provide a YouTube link. Avoid moving the timing around randomly. Verify you haven’t disturbed coil wiring. Test the condenser if need be - again post if you don’t know how.

2) Fuel - in this particular case (with a new and untuned MPS) I’d have stated by putting vacuum directly on the MPS and verifying the MPS connection all the way back to the ECU if necessary. I’d be verifying CHT resistance and wiring after playing with the resistor (which shouldn’t be in a late car anyway). observing plugs condition for grossly rich or lean conditions post photos. Use stating fluid if need if you think you aren’t getting fuel. Trigger points wiring as suggested by Emery. Grounds - did you knock off - disturb grounds serving injectors? Edit: did you bench test, the MPS for leakage - primary coil resistance, inductance etc on the bench before throwing it in the car?

3) Compression - don’t touch valves or anything at the moment. It certainly didn’t change due to a MPS swap or any of the other changes that were made.

Ron, here to help but at this point I’m not sure where to start - you need to get settled on what condition you want (points vs Pertronix) and how you intend to run the fuel injection (with resistor or not; I recommend without). You need to stabilize your timing settings.

You can work through this! Don’t give up. Be methodical in the approach.

[Ron914]

This is going to be a tough love post.

When you encounter a problem - don’t run off like a squirrel on meth and start changing and swapping parts. You’re getting distracted and confused by all kinds of parts changes and assumptions. The random changes to timing and/or retard aren’t helping.

You should have visually checked and verified spark at each plug before jumping to conclusions and swapping from Pertronix back to points. Maybe I’m misunderstanding what led to that decision.

There is nothing going on in the distributor cap that would have changed overnight / since the MPS swap that would account for the behavior you’re describing. Could be as simple as the cap not having been properly seated or bumped during the MPS removal / install. Again I’m probably not understanding all that happened.

There is literally no telling what’s going on after all that chaos.

When you encounter the unexpected - go back to the basics. Avoid the urge to start swapping parts. Change one thing at a time. If it doesn’t help, revert to the original condition and don’t keep stacking changes.

The basics:

1) Spark. Visually observe spark at the plug. Set static timing at 7-8 degrees if the points are still in there. If you don’t know how to do this - ask and we’ll post instructions or provide a YouTube link. Avoid moving the timing around randomly. Verify you haven’t disturbed coil wiring. Test the condenser if need be - again post if you don’t know how.

2) Fuel - in this particular case (with a new and untuned MPS) I’d have stated by putting vacuum directly on the MPS and verifying the MPS connection all the way back to the ECU if necessary. I’d be verifying CHT resistance and wiring after playing with the resistor (which shouldn’t be in a late car anyway). observing plugs condition for grossly rich or lean conditions post photos. Use stating fluid if need if you think you aren’t getting fuel. Trigger points wiring as suggested by Emery. Grounds - did you knock off - disturb grounds serving injectors? Edit: did you bench test, the MPS for leakage - primary coil resistance, inductance etc on the bench before throwing it in the car?

3) Compression - don’t touch valves or anything at the moment. It certainly didn’t change due to a MPS swap or any of the other changes that were made.

Ron, here to help but at this point I’m not sure where to start - you need to get settled on what condition you want (points vs Pertronix) and how you intend to run the fuel injection (with resistor or not; I recommend without). You need to stabilize your timing settings.

You can work through this! Don’t give up. Be methodical in the approach.

Hello @Superhawk996 @emerygt350 , I started confirming the points you have made here,
I wanted to undo all the mistakes I made on Friday so first to address why I changed the Pertronix out - 1)My brother in law thought it was a good idea,2) I read if you accidental left the ignition on it could damage the ignitor part .I don't think I have done this more than 5-10 seconds max when messing with the motor and it died after starting . Because of the burn marks I discovered on the cap and rotor I thought maybe it had been damaged . I would like to reinstall it as it eliminates the dwell setting .
Should I do this to get back to where I was ?
I tried to start the car after installing the MPS and the car would not start .
there was no vacuum on my new gauge and the car would not start,( this was my fault because I removed the gauge the night before and I forgot to connect the vacuum line ) reconnected vacuum and tried to start car again.
Car did not want to start so I retarded the timing as I had done before to get the car to start, once started I noticed the vacuum was only 13-15 inHG and was idling rough.
I tried to advanced the timing but the gauge no longer showed a high vacuum reading of 21inHg any more , no matter which way I moved my timing the vacuum stayed at 13-15inHg .

1) Spark - I checked all plug wire connections and then (not sure if this was correct) used the timing light on each plug 1-4 and checked for a pulse ( Had a pulse on all four).
Pulled cap/rotor ( it was not disturbed ) and checked ,that's when I noticed the black arcing marks on the four plug connections and on the rotor I cleaned the contact points and reinstalled the cap/rotor but I still had rough/shaky idling.
Here's where I squirreled and decided to change the Pertronix unit for points/condenser (new point and condenser set gap to .016), this made no difference.
Now for a bigger problem I think I have created for myself to correct , this is when I did my worst squirreling around.
When I tried to start car after reinstalling the distributor I did not have the distributor seated all the way as I had thought by rotating it so that it seemed properly seated . I know this because I again pulled the cap and discovered the rotor would turn telling me it was not seated properly before I turned the motor over , this is why I assume I need to get establish TDC position and reinstall the distributor . I need some guidance here before I proceed .
Since I have to pull the distributor I would like to install the pertonix back before I proceed any further .

2) Fuel- I did some checks first today and have the following new information for you .
Rechecked the coil resistance on the MPS
between pins 7-15 94.2 ohms , pins 8-10 347.1 ohms . No continuity from the MPS case to any pins . Applied vacuum to MPS and verified the same resistance valued form the coils
I did a leak down test @ 10 & 15 inHg start points ,see photo for results

I also removed my ECU and verified good continuity from the MPS plug back to the ECU plug .
I also pulled my plugs and verified if I had a groove cut in my cylinder heads for proper seating of the CHT sensor and removed the anti-seize .
here's a photo of the plugs and groove which I have #3 .



Distributor trigger contacts :
connection to ECU 12-22 continuity , 12-21 no continuity (I must not have had my probe in correctly .


CHT resistance ( with the resistor removed) ECU pin 23to GND (my outside temp.71 deg) =6.28 k ohms .
I also tested the trigger point wires themselves dizzy pin 22-ECU pin 22 000.4ohms , dizzy pin21-ECU pin21 000.3 ohms , dizzy pi2 12-ECU pin 12 000.5 ohms