What is the best way to vent the crankcase pressure on a built Stage 3-4 Predator 212 or clone?
- Thread starter unixphreak
- Start date
I've never tried that and it may throw a lot of oil up to the rockers but otherwise it would work. Most of the time folks tap the top of the sidecover for a crankcase vent. If you tried that use a clear hose for testing so you can see how much oil its pushing to the rockers. It sure beats drilling and tapping a sidecover.
Agreed on the clear hose. Wonder how much oil is "too much" oil moving through that hose to the rockers? I'm thinking of running a clear hose from the extra oil fill hole to the crank case, then a hose from the crank case to the puke tank which is vented with a small air filter. Does that make sense?
Too much oil would be more oil than can drain back into the crankcase. For venting the crankcase you always want a check valve if possible to keep crankcase pressure negative or at worst slightly positive. He is one of mine with a crankcase check valve and a power brake check valve in the valve cover. Fat hose by the TC cover is coming from the EC billet cover check valve and the other smaller hose coming from the cylinder area is from valve cover.
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My 2 cents…I run one line from the crank case to the valve cover
( to mist the valve train and equalize CC pressure ) then a vent from the valve cover to the over flow canister. I run a check valve in the CC vent to valve cover. I use this set up with all my 212-236 motors and so far it does the job
( to mist the valve train and equalize CC pressure ) then a vent from the valve cover to the over flow canister. I run a check valve in the CC vent to valve cover. I use this set up with all my 212-236 motors and so far it does the job
I always get too much oil sling from the side cover (crank & cam gears) to the valve cover.
Jus for testing, pop the valve cover off and start it up.
There's alot, more then enough oil, getting slung up to the rockers from the hole to the right in the head. Also oil coming from the drain hole in-between the lifters.
I jus don't see it necessary to run extra oil up there from the crankcase.
Jus for testing, pop the valve cover off and start it up.
There's alot, more then enough oil, getting slung up to the rockers from the hole to the right in the head. Also oil coming from the drain hole in-between the lifters.
I jus don't see it necessary to run extra oil up there from the crankcase.
Nice work.
I agree, if that hole is restricted or plugged, yes it'll definitely needs another oil suppy to the rockers.
I experimented with opening that drain back hole a lil bit. Going too big will get a ton of oil slinging to the rockers.
I found around .180"-.200" was plenty big enough for regular back yard builds.
I agree, if that hole is restricted or plugged, yes it'll definitely needs another oil suppy to the rockers.
I experimented with opening that drain back hole a lil bit. Going too big will get a ton of oil slinging to the rockers.
I found around .180"-.200" was plenty big enough for regular back yard builds.
This is one of the things I question about all the added venting. That's a pretty decent sized opening in the block and head for air and oil to get through. How much air pressure can any container that size produce/hold with that large of an opening, even with the constant "pump" action from the piston? IMO engine venting would work fine out of the rocker cover only. Two hoses and two one way valves for air out only.
You have mentioned your air pressure testing. Have you tested the air pressure at the rocker cover with and without an extra vent from block to rocker cover? If so what did you notice?
You have mentioned your air pressure testing. Have you tested the air pressure at the rocker cover with and without an extra vent from block to rocker cover? If so what did you notice?
Yea. Any other vent without a check valve always showed higher vacuum/ pressures. I added 3 and 4 check valves and didn't notice any decrease, at any rpm. 2 was the magic number. I'm sure older worn engines would be different.
I found the same pressure in the crankcase and the valve cover. In many different engine combos, they was the same pressure/vacuum, With or without check valves.
It didn't matter where I put the port for the gauge.
The biggest difference was the check valves. 1 valve outta the gov rod hole and 1 valve outta the valve cover was the same as 2 out the valve cover. Very little oil outta the rod hole compared to the side cover. But there was jus a tiny bit of mist when 2 valves outta the valve cover.
There was an increase in vacuum/pressure when I had both hoses, with valves going to the catch can. Only 1 to can and other to atmosphere, was a decrease. That kinda thur me off. But that's what the gauge said on different engines. So I figured that was the best I could find.
I left the gauge on mine, jus to show people when they come around asking about crankcase vent.
I take out 1 check valve and pressure goes up. Take out both and pressure went higher.
Even if the gauge was wrong, the bounce in the needle don't lie right???
I found the same pressure in the crankcase and the valve cover. In many different engine combos, they was the same pressure/vacuum, With or without check valves.
It didn't matter where I put the port for the gauge.
The biggest difference was the check valves. 1 valve outta the gov rod hole and 1 valve outta the valve cover was the same as 2 out the valve cover. Very little oil outta the rod hole compared to the side cover. But there was jus a tiny bit of mist when 2 valves outta the valve cover.
There was an increase in vacuum/pressure when I had both hoses, with valves going to the catch can. Only 1 to can and other to atmosphere, was a decrease. That kinda thur me off. But that's what the gauge said on different engines. So I figured that was the best I could find.
I left the gauge on mine, jus to show people when they come around asking about crankcase vent.
I take out 1 check valve and pressure goes up. Take out both and pressure went higher.
Even if the gauge was wrong, the bounce in the needle don't lie right???