Dizzy and vacuum expert needed

[4thwheel]

This isnt a BIG deal but Im hoping someone can point me in the right direction.
Rebuilt 2F with Man A Fre RV Cam idles a bit rough...
I get 11 to 13 inches HG reading on the Vacuum gauge when connected to manifold brake booster port.... Idles a bit rough, and needle on vacuum guage fluxuates as if it is vibrating with a few dips to 10 hg UNTIL...
When I disconnect and LEAVE the Retard/idle vacuum LINE OPEN on the "Big Cap Dizzy" the rough idle pretty much clears up but I still only get 13" hg on the vacuum guage....
Do I need to rebuild the Dizzy? Can I leave the line open?
Send me your experience Mud Gods...

Thanks for all the help....great advise here on Mud !!

1981 FJ40
Complete rebuilt 2F
RV Cam
Rebuilt Carb
All tune up stuff replaced
Big Cap Dizzy
600 mi on rebuild/ headbolt retorque and valve adj./oil change done
New 3mm silicone vacuum lines

 

[Cruiserdrew]

No expert but those are pretty low vacuum readings especially on a new motor. the first thing I would do is make certain the timing is spot on. Then readjust the valves.

It is possible for the vacuum pot to go bad and for the advance mechanism to get gunked up, but I don't think that should affect the idle.

ANy vacuum leaks? Make certain that stuff is all OK, make sure the EGR valve closes like it should, do the factory test on your brake booster to rule out a vacuum leak there.

I had my big cap dizzy rebuilt by JimC and the advance recurved for a desmog. he put on a new vacuum pot at that time and it's been great.

 

[4thwheel]

Thanks Ill check

No vacuum leaks...all new hoses and 3mm line

How do you check EGR valve??

Dizzy was cleaned up and a new cap/rotor prior to 2f install

Vacuum pot ...how do I check this...

Could the low vacuum nimbers be due to the RV grind cam? What should the Numbers be?

The highest reading at idle is 14 in hg using the lean drop method of mixture setting per FSM.

Anyone? Thanks

 

[Pighead]

An RV cam will not generate as high a vacuum as a stock cam...I got one too.