Hey, anyone know what the vacuum hg for a 305 TBI is? i checked all over the board and in the tech articles, even in my chilton manual, but cant seem to find anything! im going to look in the old service manual i have thats half missing but i dont think ill have any luck... i checked the vac at the rear upper manifold port and at the PCV valve hose and got 19Hg both times, trying to figure out if this is at the correct stock level or if i have a vac leak. thanks.

 

19" steady at idle? seems reasonable to me... i got 18" steady on a newly rebuilt eng (TPI), response i got to my post was basically 17-22...

 

ok i found an area in my manual with some suggestions and it looks like my vac is normal, now, question:

when i rev the engine with the throttle linkage the vac drops dramatically to about 5~Hg, as soon as i go back to idle it flies back up to ~25Hg, then settles back on 19hg. if i rev gradually, it will stay right about 19, if i let it adjust slowly.

is this normal?

 

Yes, that's normal. Vacuum drops as you increase RPM's.