Need input from big cam users.

Still working on getting the 340 to run decent.

I have it running much better than when I bought the car, but still the idle is just about impossible to get stable. So here is my basic question.

When I start the engine and let it warm up, I then hook my vacuum guage to the manifold port. The engine is in neutral. Right now initial is 22 degrees. Total is a bit high at around 38. Full in at 3000 RPM. No mechanical at idle though. Put in a second spring to cure that. But I start getting some mechanical at around 1400. Vacuum is not to port and I have an adjustable can so not involved at idle.

What I see at any point in the engine RPM is a huge swing in vacuum. The needle is bouncing from 5 to 10 inches at idle. It continues to bounce even as I increase the RPM's. Not as bad but enough to make it impossible to read. Unless I guess somewhere in the middle. Now we know the cam is a solid cam and based on some very crude measuring I think the lift is in the 480 range.

So anyone that runs a solid high lift cam. Is this bounce in vaccum normal, or I am guessing I have some intake valve bleeding going on. That is the only thing I can figure that would cause this. A vacuum leak would just lower the reading but not amke it fluctuate so much right?

Thx for offering your experience.

Oh and the engine is kinda stumbly until it reaches around 3000 RPM.