Ignition Question, My diaphragm was cracked--still not Prego! Options

[Robarabian]

Collective brain trust help needed.

Car is a 1971 1.7. Finished my rebuild, now 1911 CC's. (ECU non adjustable)

Car runs a Pertronix Ignition. Distributor was disassembled, cleaned and re-lubed.

Static timed the car and started it, and ran it for about 18 minutes at 2500-3000 rpm to break in the cam and rings. Did my oil change and then it sat for a few weeks.

Started it to finally set the timing and it started running rough, and I can tell it is on 3 cyl, sometimes 4, and spits, coughs etc. I know it isn't timed right and cant time it until it is on 4 cylinders.

Fuel pressure on an inline gauge is at 30 psi.

Pulled #1 and #2 plugs, they are the right color.

Pulled #3 and #4 and they are wet, and have remnants of being the right color from the cam break in.

Checked all the connections, but don't quite know where to start. The trigger points were clean in the distributor when I disassembled it, and it ran right for cam break in.

Cap, rotor, plugs, wires are all new. MPS holds vacuum.

Thoughts on what I am missing here or where would you start digging first.

I thank you in advance.

[JeffBowlsby]

In your first post you said your “MPS holds vacuum”.

That later changed?

[Robarabian]

Yeah, I didn't give it long enough when I tested it. After a minute it bled down quick... When I went through Pbanders article like 5 times, I started slowing down and following it closer. I am novice at this part, so learning.

So when I disassembled the sensor, that diaphragm began to crumble in my fingers....

In your first post you said your “MPS holds vacuum”.

That later changed?