Vacuum Pump Outlet — Not Inlet
The breather tank belongs on the discharge side of the vacuum pump.
That’s critical.
Moroso’s vacuum-pump instructions specifically warn against installing a catch can between the engine and vacuum-pump inlet on the referenced pump system.
Instead:
VALVE COVER / CRANKCASE → VACUUM PUMP INLET
then:
VACUUM PUMP OUTLET → BREATHER TANK
The breather tank catches oil residue discharged by the pump.
Follow the instructions for the specific Moroso vacuum pump being installed, since plumbing sizes and layouts can differ between pump models.
Single -12AN Male Connection
Moroso equips the 85465 with a:
-12AN male fitting
That provides a substantial connection for racing crankcase-vacuum and dry-sump vent plumbing.
For ecommerce data, list:
Inlet Size: -12AN Male
Do not simply describe it as a “12AN tank.”
The AN designation refers to the plumbing connection.
Internal Baffling
The 85465 uses internal baffling for air/oil separation.
That’s important because the tank’s job isn’t merely to provide additional hose volume.
Oil-laden vapor enters the tank and changes direction and velocity around the internal structure.
This encourages suspended oil droplets to separate from the airflow and remain in the tank.
Conceptually:
OIL-LADEN AIR ENTERS
↓
INTERNAL BAFFLING SEPARATES OIL
↓
OIL COLLECTS IN TANK
↓
AIR EXITS THROUGH FILTER
This makes the 85465 both a breather tank and a catch can.
Lightweight Aluminum Construction
Moroso constructs the 85465 from aluminum.
The standard 85465 uses a raw aluminum finish.
That keeps the component lightweight while providing a durable tank for racing applications.
For customers wanting a finished black tank, Moroso offers the closely related 85751, which uses the same basic single -12AN configuration with a black powder-coated exterior.
3-1/8-Inch Tank Diameter
Moroso specifies the tank body at:
3-1/8 inches in diameter
This compact cylindrical footprint makes it easier to package around:
- Valve covers
- Vacuum pumps
- Dry-sump tanks
- Headers
- Accessory drives
- Motor plates
The tank still needs enough surrounding space for its mounting bracket, hose connection and servicing.
6-1/2-Inch Tank Height
The aluminum tank itself measures:
6-1/2 inches tall
Moroso specifies this measurement without the filter or drain.
That distinction matters when checking engine-compartment clearance.
The complete assembly is considerably taller.
11-1/2-Inch Overall Height
Moroso lists:
11-1/2 inches overall height
for the complete assembly.
Use this dimension when determining whether the 85465 fits the proposed mounting location.
Don’t use the 6-1/2-inch tank-body dimension and forget about the breather.
Hoods have a habit of discovering measurement mistakes rather quickly.
Filtered Breather Included
Moroso includes a non-hooded, clamp-on filtered breather.
The breather allows crankcase or dry-sump vent gases to escape after passing through the tank.
Moroso lists the 68815 as the replacement non-hooded filtered breather.
It also lists the 68811 half-hooded breather as an available alternative.
Why the Filter Matters
The breather is the atmospheric outlet of the system.
It provides a controlled vent point while helping prevent outside debris from entering the tank.
Because oil mist can eventually contaminate the filter element, inspect the breather as part of normal racing maintenance.
A breather saturated with oil can become restrictive.
Petcock Drain Included
Moroso includes a petcock drain at the bottom of the 85465.
That makes servicing straightforward.
Instead of removing the entire tank, accumulated oil can be drained from the bottom.
Moroso lists the 97200 ball valve as the replacement drain component.
Check the Tank Regularly
How quickly the tank collects oil depends on the engine and vacuum system.
Variables include:
- Ring seal
- Engine RPM
- Vacuum-pump speed
- Pump vane configuration
- Engine condition
- Oil control
- Valve-cover baffling
- Crankcase vacuum level
Check the tank frequently when a new engine or vacuum system is first put into service.
Once you know its normal collection rate, establish a sensible inspection interval.
Excessive Oil Collection Means Something
A breather tank filling rapidly isn’t automatically proof that the tank is working exceptionally well.
It can also indicate a problem elsewhere.
Excessive oil discharge may be associated with:
- Poor valve-cover baffling
- Excessive blow-by
- Vacuum-pump inlet positioned near oil splash
- Incorrect pump speed
- Excessive crankcase vacuum
- Ring-seal problems
The tank is a collection device.
It isn’t a repair for the condition creating the oil.
Vacuum Pumps and Ring Seal
Racing vacuum pumps reduce crankcase pressure by actively evacuating gases from the engine.
A properly designed system can improve oil control and can support ring sealing in performance combinations.
Moroso’s vacuum-pump systems are built around several components working together:
Crankcase connection
Vacuum pump
Drive system
Vacuum regulation
Breather/catch tank
The 85465 handles the discharge side of that system.
Don’t Run Unlimited Crankcase Vacuum
More crankcase vacuum is not automatically better.
A racing engine should operate within the vacuum range appropriate for:
- Ring package
- Oil system
- Engine seals
- Wrist-pin lubrication
- Intended RPM
- Engine-builder specifications
Moroso offers vacuum relief valves and regulators specifically because vacuum needs to be controlled.
A vacuum gauge should also be used when setting up the system.
Natural Match for the Moroso 22641
The Moroso 22641 Original Design 4-Vane Vacuum Pump you already added is a natural match for the 85465.
Moroso’s own recommended Small Block Chevy vacuum-pump combination includes:
22641 — 4-Vane Vacuum Pump
63910 — Vacuum Pump Mounting Bracket
64885 — Vacuum Pump V-Belt Pulley
63845 — Vacuum Pump Drive Kit
85465 — Vacuum Pump Breather Tank
22635 — Positive Seal Fitting
Moroso also includes the 85465 in recommended GM LS vacuum-pump combinations.
That makes the 85465 an excellent cross-sell from your 22641 product page.
Natural Match for the Moroso 64885
You also already have the Moroso 64885 Vacuum Pump V-Belt Pulley in this product cluster.
That gives Pro Street Online a strong racing vacuum-system group:
22641 → creates crankcase vacuum
64885 → drives the vacuum pump
85465 → handles pump discharge and oil separation
These products should be internally linked together.
Dry-Sump Applications
The 85465 isn’t limited to external crankcase vacuum pumps.
Moroso also specifically recommends it as a remote breather tank for dry-sump oil tanks.
A dry-sump system needs appropriate tank ventilation because air separated from the returning oil must be allowed to escape.
The 85465 provides a remote filtered vent while capturing suspended oil carried with that airflow.
Moroso’s dry-sump documentation lists the 85465 specifically as the:
-12AN inlet breather tank
within its dry-sump component system.
Wet-Sump Vacuum-Pump Applications
A conventional wet-sump racing engine can also use the 85465 as part of a mechanically driven crankcase-vacuum system.
The oil remains in the engine’s oil pan, while the external vacuum pump evacuates crankcase gases.
The pump discharge then routes to the 85465.
That makes this tank useful for performance wet-sump combinations including appropriately configured:
- Small Block Chevy
- Big Block Chevy
- GM LS
- Small Block Ford
- Other racing engines
The tank itself isn’t engine-specific.
The surrounding pump brackets and drive hardware are.
Not a Vehicle-Specific Product
Your distributor feed lists:
Fit Type: Vehicle Specific
That should be changed.
Moroso 85465 is a universal racing breather tank.
It doesn’t care whether the engine is installed in a Camaro, Mustang, Nova, Corvette, pickup or tube-chassis drag car.
Compatibility depends on:
- -12AN plumbing
- Vacuum-pump or dry-sump system design
- Available mounting space
- Appropriate vent requirements
Recommended catalog attribute:
Fitment Type: Universal
Mounting Bracket Included
Moroso includes a mounting bracket with the 85465.
Moroso lists the 63401 as the replacement mounting bracket.
The tank should be mounted securely and upright in a location that provides access to:
- -12AN connection
- Breather
- Drain
- Mounting hardware
Don’t support the tank by its hose.
Keep It Away From Heat
Choose the mounting location carefully.
Avoid placing the tank immediately against:
- Headers
- Turbocharger turbine housings
- Exhaust manifolds
- Hot downpipes
Excessive heat can increase oil vapor and unnecessarily heat the breather assembly.
Also leave enough room to remove or service the filter.
Moroso 85465 vs 85751
These two products are closely related.
Moroso 85465
Connection: Single -12AN male
Construction: Aluminum
Finish: Raw aluminum
Moroso 85751
Connection: Single -12AN male
Construction: Aluminum
Finish: Black powder coat
Moroso lists the same basic dimensional layout for the black 85751:
3-1/8-inch diameter
6-1/2-inch tank height
11-1/2-inch overall height
The major purchasing difference is finish.
Moroso 85465 vs 85469
The 85469 you added earlier uses:
Dual -12AN connections
rather than the single -12AN connection on the 85465.
That makes the 85469 useful where two large vent connections need to terminate at the same breather tank.
85465
Single -12AN
85469
Dual -12AN
Choose according to the actual plumbing architecture rather than assuming the dual-inlet version is automatically better.
Moroso 85465 vs 85466
Moroso also offers the 85466, which its current catalog identifies as a vacuum-pump breather/catch tank.
Moroso’s dry-sump documentation identifies:
85465 — single -12AN inlet
85466 — dual -12AN inlet fittings
Again, the key selection factor is the number of vent connections required by the system.
Moroso 85465 vs 85474
The Moroso 85474 you recently added serves a substantially different purpose.
Moroso 85465
Open filtered racing breather tank.
Commonly installed on:
- Vacuum-pump discharge
- Dry-sump tank vent
Moroso 85474
Closed inline air/oil separator.
Used in an appropriate PCV-style circuit where vapor continues downstream rather than venting through an atmospheric filter.
These should not share the same ecommerce description or application language.
Moroso 85465 vs 85406
The 85406 is the lightweight polyethylene breather tank you added earlier.
85406
Black polyethylene
Single -6AN connection
Suited to lower-flow remote vent applications where -6AN is appropriate.
85465
Aluminum
Single -12AN connection
Specifically recommended by Moroso for racing vacuum-pump and dry-sump systems.
The -12AN connection gives the 85465 substantially greater plumbing capacity.
Replacement Components
Moroso lists the following service parts for the 85465:
68815 — Non-Hooded Filtered Breather
68811 — Half-Hooded Filtered Breather
97200 — Ball Valve
63401 — Mounting Bracket
That’s worth including in the ecommerce page because this is a serviceable racing component rather than something that necessarily needs to be replaced as an assembly.
Emissions Notice
Moroso states that the 85465 is:
Not legal for sale or use on pollution-controlled vehicles.
That disclaimer should remain on the Pro Street Online product page.
This is purpose-built racing crankcase ventilation hardware.
Do not position it as a universal emissions-compliant replacement for a production PCV system.
Package Dimensions
Your distributor data lists:
Package Height: 3.17 cm / approximately 1.25 inches
Package Length: 34.8 cm / approximately 13.70 inches
Package Width: 21.59 cm / approximately 8.50 inches
Package Weight: 612.36 grams / approximately 1.35 pounds
Those are distributor shipping attributes.
For installation planning, use Moroso’s actual product dimensions:
Tank Diameter: 3-1/8 inches
Tank Height: 6-1/2 inches without filter or drain
Overall Height: 11-1/2 inches
Country of Origin
Your distributor data identifies the 85465 as:
Country of Origin: United States
Retain that as the product’s supplied country-of-origin attribute.
Moroso 85465 Specifications
Part Number: 85465
Product: Breather Tank / Catch Can
Primary Application: Racing vacuum pumps and dry-sump tanks
Fitment: Universal
Construction: Lightweight aluminum
Finish: Raw aluminum
Inlet: Single -12AN male
Internal Design: Baffled for air/oil separation
Tank Diameter: 3-1/8 inches
Tank Height: 6-1/2 inches without filter or drain
Overall Height: 11-1/2 inches
Breather: Non-hooded clamp-on filtered breather
Drain: Petcock
Mounting Bracket: Included
Replacement Breather: Moroso 68815
Optional Half-Hooded Breather: Moroso 68811
Replacement Drain: Moroso 97200
Replacement Mounting Bracket: Moroso 63401
Package Weight: Approximately 1.35 pounds, according to supplied distributor data
Country of Origin: United States, according to supplied distributor data
Emissions Status: Not legal for sale or use on pollution-controlled vehicles
Who Should Buy the Moroso 85465?
The Moroso 85465 makes sense for builders assembling an appropriate:
- Racing crankcase vacuum system
- Dry-sump oil system
- Wet-sump engine with external vacuum pump
- Small Block Chevy race engine
- Big Block Chevy race engine
- GM LS race engine
- Small Block Ford race engine
- Drag-racing engine
- Circle-track engine
- Pro Street competition build
It’s particularly well matched to systems already using a single -12AN discharge or vent line.
Final Verdict
The Moroso 85465 Vacuum Pump Breather Tank is a purpose-built racing component for managing the oil-laden discharge from crankcase vacuum pumps and venting compatible dry-sump oil tanks.
Its lightweight aluminum body incorporates internal baffling, while the single -12AN connection, filtered breather, bottom drain and included mounting bracket provide the basic hardware required for a clean remote installation. Moroso specifies a compact 3-1/8-inch diameter, with the complete assembly standing 11-1/2 inches tall.
More importantly, Moroso itself repeatedly specifies the 85465 in its racing vacuum-pump systems.
That makes it an especially strong companion to the 22641 4-Vane Vacuum Pump and 64885 V-Belt Pump Pulley already in your catalog.
Just put it on the correct side of the pump.
The vacuum pump wants to pull directly from the crankcase.
The breather tank belongs on the discharge side catching what the pump throws out.
Plumbing those backward is a surprisingly expensive way to prove that AN fittings can be connected in more than one direction.
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