Skip to main content

Hey Guys,

I just got my EMPI Breather Box.  I am going to vent my valve covers to this box and then back into the carbs.  However, I am puzzled by the diagram below.  It shows the screen and filter above the hose entry and exit points.  It would seem to me that one or the other should be on the opposite side of screen and filter.  What would stop the oil residue from flow out to carbs?  Am I missing something here?

Empi Breather


Images (1)
  • Empi Breather
Original Post

Replies sorted oldest to newest

Cast aluminum crankcase oil breather box setup relieves excess crankcase and valve cover pressure. Higher revving or high compression engines may require more crank and cylinder head ventilation to reduce oil blowby. Internally baffled box includes foam to collect oil vapors before returning them through the oil fill vent. Includes cast breather box, fittings and valve cover vents, 8 feet of 1/2 inch hose, clamps and hardware. Requires drilling  Mounts to your fan shroud. 00-8544-0

That breather box is not imagined for PCV (positive crankcase ventilation) with hose going to carb.  It intends to vent pressure to open air though gap between lid and box.  With that in mind, you can enhance the breathing by putting a washer between the lid and box on each screw (to make gap bigger) and replace the sponge with brass or stainless steel  pot scrubber (less restrictive air flow).

The idea is the screens will filter oil out of the vapors pumped out of the oil filler neck and valve cover vents. The collected oil on the screens drains to the bottom of the box to a level high enough to drool back down the hoses to where it came from (thus the hoses must always aim downwards from the box).

Theoretically you could seal the lid to the box with gasketing, remove the sponge, pop a hole (or two) above the level of existing hole for vent(s) hose to carbs.  The result would be a somewhat rudementry PCV  -- that a CA Smog Referee would never approve.  So what would be the point?

I now have 3 breather boxes.  I started with only the CB box with connections to my air cleaners and the fuel pump block off plate.

Then, when I got my Berg 5, I vented it to an EMPI box on the front side of the firewall (the other side from the engine).

Later I decided to vent my valve covers. At first, I connected them to the same box as the transmission.  ALB advised against that so I added another EMPI box for the valve covers.

The bigger the engine, the more breather you need.

I've gone through a few different configurations(yes, three). If your engine is over 2 liters(mine is 2165cc), you need MORE than that little EMPI thing. It's great to vent both valve covers, but (I think) the 3-4 side gets a whole LOT more oil pumped into it than the 1-2 side.

I use a couple wads of stainless steel Chore Boy pot-scrubber pads in the top of my baffled 2" x 24" breather tube. Yes, it's 2 feet long. It's all about volume and LARGE hose to feed it. It works extremely well. It works so well that it's not connected to my air cleaners any more.

I bought a small Evil Energy breather that has two ports, one from that long breather and the other from the dry sump tank.

In conjunction with the Autocraft dry sump pump, 8 quart tank(6 quarts oil and foam/air space), all the lines, remote filter, thermostat and cooler, it gets a bit complicated.

The biggest help to breather fumes and blue smoke was rebuilding the heads AND replacing the pistons/cylinders and RINGS. The 2nd ring is Total Seal(the early 911 guys do this too). A healthy engine is of paramount importance to minimal vapors.

That Berg breather that Gordon linked? That thing WORKS.

Last edited by DannyP

My engine is 2276.  I have the other empi breather box Wolfgang has pictured.  I have two hoses from that box dumping into each carb.

The reason i wanted to add breather box for valve covers is due to oil leaks.  I have been battling small leaks at the valve covers that drip on to the exhaust.  I have tried all the various gaskets and methods and still seam to get leaks.  I thought crank case pressure might be causing it so I though I would give the vents a try.  I could run hose from the vents to exiting breather but that is a lot of hose to wrap around to that side of the motor.

The Beck Speedster has a nice shelf above the fire wall that would be a good spot for the new breather.



Images (1)
  • Breather

I agree with everything Danny says about using Total Seal piston rings !... Period ! I had an unacceptable amount of blow-by on my 2165. I pulled the engine out again, disassembled it and only put in the Total Seal oil ring. The blow-by went to nearly 0 !

I removed the that dumb looking EMPI "sluse-box" filler from the engine and replaced it with a tiny breather-filler unit.  I retained the breather box you have but ran two hoses to it from the back side and thru the firewall. There, I connected hoses to the valve covers. Which, by the way, are now easier to remove because they don't need to be "fished" thru and up into the engine compartment.

Here's the only photo I have and if you can enlarge it you will see that little aluminum breather on the oil filler port. It has a little paper filter inside that's replaceable.

The breather box up on top has no hoses showing. You can see that I originally had hoses  connected  to the air cleaners but no more.

Many times over the years of playing with this stuff, I have bought a lot of gadgets and my evaluation has ranged from total disappointment to total satisfaction. In this case, the Total Seal rings were a real winner in controlling the oil and blow-by.

By the way, that EMPI "sluse-box" leaks. Yes, there is an "O" rings under the cover but not on the machine screws that hold on the cover. The bottom of the box retains a small amount of oil that doesn't drain back into its engine. It leaks around the threads of the screws down there. Also you get a big "bloop" of oil dropping out when you remove the cover which is never fun to wipe up. Last, myself and two others have had this box loosen up at the connection to the engine and flop over. One guy's flopped into the fan belt. Nope, I don't recommend using this box...............Bruce

Bobby... Yes, but in the breather box.  Only the two hoses from the valve covers were needed. I installed two each, 6" long 1/4" pipe nipples into the back of the breather box. The reason for this is so I could detach the breather box from the firewall and pull the whole assembly out to clean and inspect the inside of the breather box occasionally. This way, I didn't have to crawl up in behind the firewall to detach those hoses from the breather box.  (note that the breather box is mounted close to the top of the engine compartment).  I drilled two holes in the firewall large enough to allow the hose clamps on those hoses  to pass thru the firewall too. These holes are sealed with a high density foam ring around the 1/4" pipes to keep air and other things from entering the engine compartment except thru the air intake grill in the rear deck lid.

In my photos you can see the old breather hose elbows still in the air cleaner tops. Later I replaced those with a new, un-drilled set............Bruce

P.S.  I don't know where I got those foam  rings/grommets from. Just something I saved in my "Biz-Bag" !  (big box of junk you think you might need later ?)

Add Reply

Post Content
Link copied to your clipboard.