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]

First on the to do list

MPS is leaking down too fast. Something not right. Did you use a light coat of grease on the gasket. Did you assemble the gasket / diaphragm in the order indicated? 1st time i did one it didn’t seal properly - didn’t grease the gasket to see what happens - it leaked.

It should be holding vacuum much longer than it is.

The other stand out is the ECU trigger points. They alternate as you rotate the engine. Did you only check them in only one position?

Whether or not I go back to Pertronix would depend on which you have. The newer version 2 & 3 supposedly has a protection built into them to prevent the ignition on burnout problem of the originals. So if I had an original - stay points. If you have one of the later 2 or 3’s I’d be fine to change back. The main downside of Pertronix is it just isn’t as easy to see it work but if you’re getting spark at the plugs - good enough.

FWIW - check spark visually. The timing light method can fool you if you have soot fouling of plugs. Just because the timing light flashes doesn’t not guarantee a spark has jumped the gap. Your plugs are looking janky but i don’t think they are the root cause of your problem. They have been too rich due to the CHT resistor and the fact that your MPS isn’t working properly.