Wagenwerks™ · Engine Rebuild & Parts Sourcing
VW Type 1 Engine: OE and Reference Numbers
AS41 case, 1600cc dual-port heads, doghouse cooling, fuel pump, and oil pump – all important numbers for the late Type 1 engine at a glance.
If you want to build, overhaul, or correctly identify an air-cooled VW Type 1 engine as a replacement engine, you can hardly avoid the old OE and reference numbers. Especially with the 1600cc dual-port engine – i.e., the late AD/AS engines – the same questions keep arising:
- Which AS41 engine case is correct?
- What is the number for a 1600cc piston and cylinder set?
- Which cylinder heads belong to the dual-port engine?
- Which parts are needed for doghouse cooling with an external oil cooler?
At Wagenwerks, we don't use such numbers as a substitute for a technical inspection, but as an important guide for restoration, engine overhaul, and parts sourcing. Especially with VW T1, T2, Beetle, and other air-cooled Type 1 applications, many engines have been modified, replaced, or mixed over the decades.
AS41 is not an OE number
Important upfront: AS41 is not a Volkswagen part number, but rather the designation for the engine case material or case design. When buying parts, AS41 is often used as a synonym for a late magnesium Type 1 case. The actual reference number for the late 1300–1600cc engine case is often:
Case Reference Number
043 101 025 D — Magnesium engine case for 1300–1600 cc Type 1 engines
Another point: The engine case itself is not "dual-port" in the stricter sense. Dual-port – also known as twin port – primarily refers to the cylinder heads and the intake system. Therefore, when building, the complete package must always be considered: case, heads, pistons/cylinders, intake manifold, cooling, oil pump, and fuel supply.
01 — Basic Engine: Important OE/Reference Numbers
| Assembly | Description | OE/Reference Number |
|---|---|---|
| Engine Case / Crankcase | AS41 / Magnesium, Type 1, 1300–1600 cc | 043 101 025 D |
| Piston and Cylinder Set | 1600 cc, 85.5 mm bore, 69 mm stroke, complete set | 311 198 069 B |
| Cylinder Head Bare | 1600 cc dual-port, Type 1 | 043 101 355 C |
| Cylinder Head Complete / Assembled | 1600 cc dual-port, valves/springs assembled | 043 101 065 S |
| Cylinder Head Complete Set / Aftermarket | Often used for complete 1600cc dual-port heads | 043 101 355 CK |
Wagenwerks™ Note
For complete cylinder heads, 043 101 355 C, 043 101 065 S, or 043 101 355 CK appear as reference numbers depending on the supplier. Always clarify the specific version (bare or assembled).
02 — Doghouse Cooling for AD/AS Engines
The late 1600cc dual-port engines are often equipped with so-called doghouse cooling. In this system, the larger oil cooler is no longer located directly in the main airflow of the fan shroud but in a case part attached to the side or rear. This changes the cooling air routing compared to earlier engines.
Important for Doghouse Assembly
- Oil cooler alone is not enough
- Order matching fan shroud
- Check wide fan impeller
- Adapter between case and cooler
- Provide all 4 oil cooler seals
- Don't forget the hot air deflectors
| Assembly | Description | OE/Reference Number |
|---|---|---|
| Doghouse Fan Shroud | Large fan shroud, usually with heater outlets | 113 119 025 Q |
| Doghouse Fan Impeller | Wide fan impeller for Twin-Port / Doghouse | 113 119 031 B |
| Large Doghouse Oil Cooler | Oil cooler for late 1600cc Twin-Port engines | 113 117 021 |
| Oil Cooler Adapter / Connection Base | Adapter between engine case and oil cooler | 113 117 301 |
| Oil Cooler Seals | Seals for doghouse system, usually 4 pieces for dual-port | 021 117 151 A |
| Doghouse Outlet Plates | Hot air routing to the outside – absolutely check with photo/sample | check depending on version |
| Front Plate over Transmission Bellhousing | Plate with cutout for doghouse hot air outlet | check depending on vehicle/engine |
03 — Fuel Pump for Late AD/AS Engines
For late Type 1 engines with an alternator, the fuel pump is different from older DC generator engines. Here, the version for the short pushrod (approx. 100 mm) is generally used.
| Assembly | Description | OE/Reference Number |
|---|---|---|
| Mechanical Fuel Pump | For Alternator version | 113 127 025 G |
| Fuel Pump Pushrod | Short pushrod, approx. 100 mm | 113 127 307 A |
| Fuel Pump Flange | Bakelite flange between case and pump | 113 127 303 / 113 127 303 C |
| Seals | Below and above the Bakelite flange | check according to set |
Wagenwerks™ Note
Always measure the pushrod length on the removed engine before ordering. An incorrect pushrod means incorrect pump height and thus false air or leakage at the flange.
04 — Intake Manifold for 1600 Dual-Port
The so-called intake manifold for the 1600 dual-port engine is not a single cast part, but consists of several components: a central section with a carburetor flange, left and right end pieces, two rubber sleeves, and seals at the cylinder heads and carburetor base.
| Assembly | Description | OE/Reference Number |
|---|---|---|
| Intake Manifold Central Section | For 1600 dual-port, 34 PICT | 113 129 701 AQ / 113 129 701 CA |
| Intake Manifold End Piece Left | Dual-port end piece left | 113 129 709 G |
| Intake Manifold End Piece Right | Dual-port end piece right | 113 129 710 D |
| Rubber Sleeves | Connection between central section and end pieces, 2 pieces | 113 129 729 B |
| Seals at Cylinder Head | Intake seal dual-port, 2 pieces | 113 129 717 A |
| Carburetor Base Gasket | For 34 PICT carburetor | 113 129 707 A |
05 — Oil Pump as a Complete Set
For the oil pump, it is particularly important to check which camshaft and case are installed. For late 1300–1600cc Type 1 engines with 8mm studs and a 4-rivet camshaft, the following combination is often used:
| Assembly | Description | OE/Reference Number |
|---|---|---|
| Oil Pump | 26mm gears, for 4-rivet camshaft, late Type 1 engines | 111 115 107 BK |
| Oil Pump Cover | Cover for 8mm studs | 311 115 141 C |
| Pump to Case Gasket | Inner oil pump gasket | 111 115 111 B |
| Cover to Pump Gasket | Outer oil pump gasket | 111 115 131 B |
| Sealing Nuts / Cap Nuts | For oil pump cover, 4 pieces | 111 115 161 |
Don't just order by displacement
- Check camshaft type first
- 4-rivet vs. other versions
- Note stud diameter
- Clarify case version
- Earlier engines have different pumps
- Always order cover and gaskets together
Why these numbers are just the beginning
OE and reference numbers greatly assist in parts procurement. Nevertheless, they do not replace inspection of the specific engine. Especially with air-cooled VW engines, many units have been modified over decades. An AS41 case can have different heads, a 1600cc can be assembled with an incorrect fan impeller width, and a doghouse shroud can be installed without correct hot air evacuation.
At Wagenwerks, we therefore pay particular attention to:
- Engine code (e.g., AD or AS)
- Case type and oil passages
- Camshaft type and matching oil pump
- Cylinder head version, valve sizes, and spark plug threads
- Doghouse cooling with all sheet metal and gaskets
- Intake, carburetor flange, and false air sources
- Fuel pump, pushrod length, and flange
- Overall package suitable for vehicle, use, and registration
Wagenwerks™ Principle
It's not the displacement that determines which parts fit. What matters is the entire engine package – case, camshaft, heads, cooling, and fuel supply considered as a unit.
Frequently Asked Questions
Is AS41 an original VW part number?
No. AS41 is not an OE number, but a designation for the engine case or the material version. As a reference number for late 1300–1600cc Type 1 engine cases, 043 101 025 D is often used.
What does dual-port mean for the VW Type 1 engine?
Dual-port means that the cylinder heads have separate intake ports for the two cylinders on each side. In English, this is often referred to as Dual Port or Twin Port.
What bore does an original 1600cc Type 1 engine have?
The classic 1600cc Type 1 engine has an 85.5 mm bore and a 69 mm stroke. A typical piston and cylinder set is listed under 311 198 069 B.
Can I simply retrofit a doghouse oil cooler?
Not without further modifications. Converting to doghouse cooling requires not only the oil cooler but also the matching fan shroud, the wide fan impeller, the adapter, the correct seals, and the correct hot air deflectors. Just replacing the oil cooler is not enough.
Wagenwerks™ Conclusion
The Most Important Numbers for the Late Type 1 Engine
- 043 101 025 D — AS41/Magnesium engine case
- 311 198 069 B — 1600cc piston and cylinder set (85.5 mm)
- 043 101 355 C / 043 101 065 S — Dual-port cylinder heads
- 113 117 021 — Doghouse oil cooler
- 113 119 031 B — Wide doghouse fan impeller
- 113 129 701 AQ / CA — Intake manifold central section
- 113 127 025 G — Late fuel pump (alternator)
- 111 115 107 BK — Matching oil pump (26 mm, 4-rivet)
If you want to properly build a VW T1, T2, or Beetle with a 1600cc Type 1 engine, you shouldn't just order individual parts, but check the entire system. This is precisely the difference between "fits somehow" and an engine that runs smoothly, cools well, and remains reliable in the long term.