Car dropped 250 RPM and is now stuttering

WSUTARD said

If I am understanding your Transfer Port Sync post correctly, I use the curb idle screw to adjust as I normally would, but instead of adjusting the actual idle to my chosen RPM I look at the transfer port area and adjust the curb idle screw till the exposure of the t port is .025/.03 "high". Then, instead of setting the RPM with the curb idle screw I now set the RPM with timing advance adjustments, but ensuring that I'm not setting it too high so I don't detonate.

Sorry if this seems like a total repeat of your writeup but I had to read it about 10 times before it clicked...assuming what I said above is correct.

Click to expand...

You got it! But you may have to add bypass air to control the idle quality and speed as well. The bigger the cam, the more bypass it wants.
I have had a 270/110 cam and it didn't want much bypass. I have a manual trans tho, and so I do not have to compensate for the TC dragging the idle down, when put into gear.
In post #9 you gave us a video of the idle jumping up and down some 200 rpm. This is usually called surging. It is very often the result of a fault in the power-valve system. For your Eddy this means, in all likelihood the metering rods were not staying down. The springs were too strong for the amount of vacuum the pistons were seeing. The most logical conclusion I came to was a large vacuum leak.