My 72 has a 454 with a 177CFM blower, at high RPM's oil leaks from the back of my intake. I have replaced the gasket material on the intake several times, even tried no gasket just RTV type items. It still leaks, ( it runs down the back of the bell housing and drips ) I have one breather in my passanger valve cover, my buddy said I probably have the wrong rings, he said this is the reason for the blow by, ( they make specific rings for blower cars to handle blow by ) is this true ?? I thought the pressure had no place to go with only one breather, I was going to add an additional breather on the drivers side. I also noticed that my PCV valve is always pushed up after runs at high RPM's.... Your input is greatly appreciated !!

quick,
You dont need special rings, just good ones that are not worn out. Any good quality moly ring set should handle the boost from that blower. Have you done a leakdown test yet to see if the rings are sealing ? How fresh is the engine ? Etc. It must be building up a lot of pressure to be pushing out the intake gasket, especially if you have a breather of any type on it. Are you absolutely sure it is the gasket leaking ?
Where do you have the pcv hooked up to ? If its in the manifold, you need to move it because it would be getting boost pressure instead of vacuum at wot.

Hello,

I run a .060 over 454 with a B&M 174 cid blower. Using Speed Pro rings. I bought the type that needed to be file fit. I file fit each ring to specs that allow for heat expansion (.022/.024 for top ring, and .016/.018 for second ring). The end gaps of non-blown street motors are around .016/.018 for top ring and .010/.012 for second ring.

I doubt the ring end gaps are causing you problems. Assuming you are making 5 or so lbs of boost????

I have been running a PVC valve and a wide open breather. PVC was connected to rear port of base plate on Holley 850. Is your PVC connected to the carb above the blower???? Or is your PVC connected to the intake manifold below the blower???? If below the blower, you could be forcing boost pressure past the PVC valve.....or the PVC valve may be malfunctioning due to weak vacumn signal below the blower.

I just installed a Holley HP 1000 with no vacumn ports, so I am strongly considering getting rid of the PVC and running a breather on each valve cover.

Do you have crankcase evacuation systemm on your car? I did years ago. Everytime I got on the car, then backed off it........tremendous pressure built up in the engine and spewed oil from dipstick. Running a crankcase evacuation system with mufflers on the street is something I don't do anymore.

Interesting that oil blow out is consistently at rear of your intake. As if that were some "weak link" as far as gaskets are concerned.

Beneath my intake, I am running a GM oil tray to keep oil splash off the intake. Worth considering. Although I doubt it would cure a severe pressure / oil blow out situation.

Where is your PVC connected? What type of breather are you running?

....Joe.

i have always run 2 breathers on the pass side valve cover on my blower motors, seemed to cure a lot of crankcase pres. On the manifolds, i always roughed up the under side on an alumn. intake where the end seals go(about 80 grit) to give something for the rtv to grip on(also ck your dist. seal) of course, your rings gotta be sealing good-on high boost engines, i run hell fire rings, but standard should be ok for what you have

The next time you have the intake off try using Permatex "The Right Stuff" instead of RTV. Just be warned when it sets up it is very difficult to get it off but it won't leak.

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