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]

I’m going to post this over here

This is another change you’re completely neglecting.

Generally speaking - you’ll find NGK and other spark plug makers recommend against anti-seize. This is because the plug needs a good ground path to the head to spark.

Anti-seize also modifies the torque spec - so the spec they give you is for no anti-seize. Torquing to their spec with lube can lead to stripping threads.

Now for reality. I use copper based anti-seize but very sparingly (not like this photo). You should get a good enough ground from contact between the plug shoulder and the head. But - - you’ve also added the CHT sender in the mix and ground path. If the CHT sender isn’t allowing a solid connection between the plug and head - ground path could be compromised.

I’m not posting this to shame you but rather to get you thinking about how many changes were introduced since it ran last and that things as simple as too much goop and/or a improperly seated CHT sensor could be causing your misfire / engine rocking that you initially described.

Note: if you don’t have a slot cut into the head to allow that CHT to seat properly, it often takes some creative bending to get that CHT down into the spark plug pocket correctly.

Examples / pictures
http://www.914world.com/bbs2/index.php?showtopic=312118