Hey, so I'm slowly gathering parts for a 8ba flathead build. Trying to figure out all the details etc etc. I purchased an intake manifold from Matt's (Geardrive Speed & Custom). It's the 2x2 intake with 2 separate logs. It's basically a 1 inch flat plate with the logs on top. There are no runners underneath, just straight into intake ports of block. Anyone got any good ideas of how to do a clean/hidden pcv? I didn't really want to drill a hole in intake and run fittings/hoses up to carbs. Any help is welcome. Thanks
I’ve run 2 different early intakes on 8ba engines with pcv valves. One was a edelbrock slingshot and one was a 2x2 offy. First one I did I put a port in 2 runners from below one under each carb and ran it Into a pcv valve fit into where the road draft tube would have in the valley. So it was all under the intake. I learned it wasn’t necessary 2 run 2 ports under the manifold and switched to just one. Worked the same. So my point I guess is even though you don’t want to drill the manifold, you could. I’d drill and tap one hole in the bottom and run a hose to a pcv valve below. Clean and easy. You can always plug it if need be. I did post a thread on doing this on here a while back.
Do you have to pull vapor from the crank cavity, or could you just pull from the lifter valley? Basically just screw a PCV valve into the bottom side of one port. No hoses needed? As long as the valve is oriented in its proper operational position?
You need all 8 cylinders to act on the pcv for proper operation. What does the bottom of the intake look like?
I don't have a picture of the bottom of intake handy, as i am not home, but the bottom basically looks like the topside of the main plate pictured above. Just a solid chunk of aluminum with vertical ports. There is no runner detail exposed like adam401's pictures. There's basically nowhere to drill into underneath and get into the runner. One thing i thought of was drilling and tapping a hole into each intake port on the block and then connecting with a hose, which would require zero holes in intake.
How about emptying the vapor into the underside of an air cleaner? I thought an old Shivvy I had did that.
I think that was an air intake for the PCV not an exhaust into the air cleaner. It had it's own foam air filter mounted to the inside of the air cleaner also.
I’m experimenting with a setup on my current 8ba right now. Instead of a pcv or roaddraft tube, I ran a line from a sealed fitting where the road draft tube should connect and ran it out parallel with the rear oil fill. Basically just relocated the road draft tube. This car doesn’t run a mechanical fuel pump. So far I think it’s working fine. It’s not a street car so my experience with the setup it 1/8th mile intervals but so far so good. You could certainly fab something more elegant than my setup. Zero drilling the manifold required.
So it goes from the old road draft tube back into the crank case where the fuel pump mounts, correct? How does that vent any fumes or help vent the engine? Basically you could just plug the vent tube and accomplish the same thing, unless I am misunderstanding what you did.
The fumes do not re-enter the crankcase. There is a fitting pressed into the opening where the road draft tube should be pressed in the valley below the intake. From that fitting a line runs through the valley and passes through the rear of the manifold out of the engine. I didn’t explain that well at first.
Is it hooked to the vacuum side of the intake anywhere? If not I guess I don't see where it is any different from a road draft tube. If it just vents the crank case to the outside of the engine. Am I still missing the concept?
It’s no different from a road draft tube. It’s a road draft tube. When you run an intake designed for an earlier engine on a 49 an later engine there is no provision for a road draft tube in the intake. Some intakes can be drilled for the later road draft tube. Some intakes there isn’t a great spot for that up front or it’s not asthetically desirable to do so. In my particular case there’s a lot of crap in the way up front and the manifold isn’t ideal to drill for the standard road draft tube.
The only problem I see with the setup is that you are drafting air from the air intake not the crankcase. Usually, you suck air from one rocker cover and vent the other. Or for flatheads, vent the back and suck from the front. You aren't having issues so it must not be a big deal. Just an observation. Nice blown Flatty BTW. I was fortunate on my 8BA that is had a draft tube in the front of the intake and all of the plumbing under the intake to vent the crankcase, it breathes fresh air from the rear mounted air intake. I installed a PCV in the draft tube hole and routed vacuum to my carb adapter above the blower. It pulls 17 pounds of suck up there and made a huge difference to oil leaks, smells and performance (that last point is an optimistic observation, I have no science to back it up)
I think a picture with the intake off would clear up a lot of confusion but I don’t have one unfortunately. The hose is connected the same way a stock roaddraft tube is and in the same location internally. it just exits from a different spot. The same paths in and out exist as stock. But no matter. Just spit balling ideas haha Dialog on here is good and I welcome it! I’ve learned a lot on here through back and forth and believe me I’m still learning.
Unfortunately with the design of your intake {a copy of the original Alexander} you now have two four cylinder engine's without some type of cross over between the intake runners. To add to the problem every intake port needs to be connected together for the vacuum needed the operate the PCV correctly. The flat plate design on your intake makes this all port pulling vacuum impossible to connect to for what's needed. The only way it would work would require a hose connected below each carb {location of needed vacuum signal} each hose can then be connected to a fitting in the flat base which would now connect under the plate to the hidden PCV located in the road draft hole in the valley of the block. Obviously that would make it rather ugly. But maybe taking the time to use say copper tubing for the connections in place of hose it would look a lot better and work well also. Ronnieroadster
The Jalopy Journal
