Thumping noise

[GRNOVA]

Hello everyone need help with a little problem(I hope)

I have a blown 383 and at cruising speeds there is a kind of thumping noise. Kind of sounds like it is coming from the exhaust. Could this be detonation? I am running an 850-900 race demon,power charger 250 blower and an MSD 6BTM. Timing is set at 34 total plugs are NGK v-power R5673-8. Vacuum is at 12 lbs before boost. And lastly the 3" exhaust flow master 40's ends at the rear with turn downs. I am at a loss.

[GRNOVA]

Just another problem to add to the pot.
Just a question that may sound dumb but here it goes. What is the proper way to vent a blown engine?
Evac system?
just plain breathers on the valve covers?
a PCV?

I am having a lot of oil leaking from the engine and need to find out what or where I am going wrong!!
leaks are from the valve covers and I have good fel pro resealables. from the harmonic balancer seal, intake.

[WS6]

Your PVC should hook back up before the blower so as to always suck. I'm not sure if it is necessary in this case, but vacuum pumps are available and you may need one. I can't help beyond that. I'd would focus on your crank case pressure issues first and then figure out the thumping noise.

[megaladon6]

and make sure you have a high flow breather on the opposite bank from the PCV. that got me for awhile, i thought i had a good breather but kept blowing out the intak/block seal. put on a k&n open breather and no more problems.

[GRNOVA]

Went out and bought a external breather can. I am going to run both breathers to this can and take the evac off of the exhaust and plug it up. I was told this weekend at a car show that this will get rid of my problem with the oil being forced out of the engine. I was also told that you do not run an evac system with mufflers, is this correct?

[Josh]

I would not rule out an axle bearing going out causing the thumping, almost sounds like the exhaust hitting the frame some times..then it gets worse!