Bob I agree with ya crankcase vacuum is a good thing, but 5" is alot, it has to have a source creating it. The only source that can create that much vacuum is the induction system. Hence my statement " you have an internal vacuum leak causing high CRANKCASE vacuum".
My thought is that you may have an intake manifold vacuum leaking into the crankcase.
We can throw all of this out the window if you are running a vacuum pump and or a header e-vac system or just call me Nuts.
Just for conversation how much intake manifold vacuum do you have at idle? What is your current idle speed?
Intake vacuum is about 8-9 at idle , which surprises and pleases me w/ the cam I`m running. About 14-15 cruising on the hi way , any throttle pressure change drops it immediately.
I have both 3/8 nipples sticking out of the back of my 1200 cfm throttle body , teed together and ran to the oil catch can , (which is coming off, no oil has shown up.) F.A.S.T. says both nipples are intake vacuum below the throttle blades.
I just tried a pan evac on the drivers side, it reduced my crankcase vacuum by 1 1/2'' up to about 4200 , didnt nail it w/ it hooked up , guess my mufflers have a little more back pressure than I thot , really thot it would work, but I`ve been told that they dont create more than about 1'' with open headers.
I think the good case vacuum comes from my gapless rings seating , 5'' aint too hi, the better the ring seal , the more vacuum .
power brakes require about 16-18'' intake vacuum on most cars.
Really not that unusual for a sealed up engine according to one of my mech./18 time record holder friends .
Like I posted before , a past friend bought a new 502 gm crate motor that had so much crankcase vacuum , he had to put an adjustable pcv valve on it /$75 !
''Its nice to not have any oil leaks too !''
Guess I`ll try putting a breather on the opposite side , just to see what diff it makes , should lower the gauge and maybe make it idle faster /vacuum leak---?? Really shouldn`t /sealed up as well as it is now , still another ?????
always experimenting -------I know it doesn`t like the opposite side breather hooked to the air filter , makes it idle way hi , aint got that figured out yet.
No I dont have an intake leak , My intake fits better than any I have ever messed with. almost could run it w/ gasket sealer only , I can see down the runners to see the port matching too , another reason I like tall single planes .
I will probly ''just for looks'' , end up with a vacuum nipple running to each side valve cover and the screw in cap on the oil fill hole.
AND THE SAGA CONTINUES ------------------''starrtrek"-----------------------lol----long *** post !
