I have been experiencing vacuum leaks from the base of the carb I know for sure, and I have fixed that. I think its leaking from the base of the intake where it meets the head surface, but I dont know how to really diagnose that. my car is idleing very rough when in gear and very high when in park. I used a vac. gauge and I am getting 19.5hg of vacuum from full manifold vac. port, and carb is tuned properly with the vac. gauge. I have done everything except the intake gaskets to try to fix the problem. please any help would be appreciated. Thanks

 

Easy way to find a vacuum leak is take some rubbing alcohol and put it in a spray bottle. Start the engine and let it idle, take the alcohol and spray it were you think it might be leaking. If the car revs a little when spraying you found the leak.

 

19.5 is a pretty good vacuum reading, especially if you have an aftermarket cam.

 

19.5 is healthy...

check this site out, it will show you how to read a vacuum guage to interpret why the engine is running rough.

http://www.secondchancegarage.com/public/186.cfm