M90 runs fine in idle but "dies" immediately when giving gas

[msoft]

My 635csi from 79 with an M90 runs fine in idle but "dies" immediately when I give gas. This only happens if the vacuum hose for "advance" is connected to the distributor. With vacuum hose removed and plugged, it runs really well. When I turn the rotor manually by hand, I believe it springs back as it should. Still, I'm thinking of cleaning the mechanism to make sure nothing is stuck. Any DIY on that? Do I have to remove the distributor from the engine to do this?

rotor.jpg (852.96 KiB) Viewed 466 times

[Ralph in Socal]

Get a vacuum tester on the distributor vacuum advance. The diaphragm may have failed causing the motor to get unmetered air. Good luck

Ralph I h

[msoft]

Thanks', good hint! I will check that! Is it just to pull the rotor upwards like any otherdistributor?

[Ralph in Socal]

There are some distributors that provide vacuum advance and vacuum retard. 2 separate vacuum ports in one vacuum pot. Check and verify both are functional if that's your system

Ralph